Is our suspension setup correctly by aftermarket strut MFR's? Is the bias correct?

[J. Fast]

As I get closer and closer to completing my racecar and reasearch more and more I'm tripping over things that keep raising questions. The most recent is our chassis cornerweights in comparison with Evo VII-IX series. The EVO VII-IX etc chassi and the 3/S are corner weighed very similar in race form. They both carry weight similarly, have nearly identical roll centers, centers of gravity, brake bias, aero, and etc.

To wrap this all together, Evo struts and 3/S TT aftermarket struts are retailed by several MFR's already setup with a spring rate of 10K front / 8K rear... 12K front / 10K rear, and etc. What I've found in the Evo community is the guys doing their homework regarding suspensions such as Meullerized, GT Works, Moton, JRZ, and AST Engineering have engineered and improved suspensions on the EVO chassi and determined if the front is sprung more, "you're doing it wrong". What that community is seeing is suspensions engineered and retailed nearly reverse. 10K front's / 12K rears, or 12K fronts and 14K rears.

If that's the case do any 3S suspensions out there have the spring and valving right (if the rear is suppose to have more spring than the front)?

So what is the reasoning and the debacle? Well, Supercar Engineering Evo Suspension Conversion adapters afford us the ability to bolt on Evo suspensions. Often the spring and valving is based off the weight bias of the vehicle. The weight and suspension bias on both is nearly identical. You would think if that were the case they would be very close to one another regarding setup?


Here's the corner weights of a 3/S (obviously it's not balanced properly and I'm not going to say whose car this is but you can see the bias)
http://i788.photobucket.com/albums/yy163/JFastMotorsports/Photo_052712_030_zpsb41a5acd.jpg


Corner weights of track Evo
http://i788.photobucket.com/albums/yy163/JFastMotorsports/IMG_3607_zps3931e394.jpg

Now here's what's available: *Note these are not Tooner shocks

Evolution IV-IX Coilovers/Springs (http://www.amsperformance.com/cart/evolution-iv-ix-coilovers-springs.html)
Welcome to Muellerized Suspension Systems (http://www.muellerized.com/products_evo89.html)

For pricepoints ranging anywhere from $3500 - $15,000 (take your breath away expensive) you get the read deals with spring rates and valving quite the opposite of what we're used to seeing. Like 14K in the rear and 11K in the front. So what gives? Are Z16A chassis supposed to be setup for more front spring or what?

A very typical OEM bias on an EVO VII-IX (which has the same suspension that we can adapt to with Supercar Adapters) is distributed 1000 lbs in the front corners and 650 lbs in the rear corners. The ideal spring rates for those weights typically for Ohlin DFV Road and Track, JRZ's, Moton and AST 5000's is 10k front and 12K rear...

[DocWalt]

Are the motion ratios even remotely close? What about ride frequency? There's a LOT of calculations & testing to do...

[J. Fast]

Are the motion ratios even remotely close? What about ride frequency? There's a LOT of calculations & testing to do...

If you buy a set of Meullerized DFV's for a 3000gt (which they make now BTW) that's how John Meuller reccomends they come. More spring in the rear. However, you can custom order them however you want. ;)

Tooner shocks are doing it wrong.

[J. Fast]

Forgot link... Welcome to Muellerized Suspension Systems (http://www.muellerized.com/products_3000gt.html)

[DocWalt]

I know they make them, Nate's planning on buying a set.

I wouldn't be at all surprised if the "tooner" companies got it wrong, FWIW.

[green-lantern]

Here's the corner weights of a 3/S (obviously it's not balanced properly and I'm not going to say whose car this is but you can see the bias)
[COLOR=#000000][FONT=Calibri][SIZE=3]http://i788.photobucket.com/albums/yy163/JFastMotorsports/Photo_052712_030_zpsb41a5acd.jpg




Bent frame? lol

Unfortunately I can’t add much to this subject right now but I'm very interested in the info.

[2fnloud]

J what about the spring ratings on ECS struts, you thinking that the spring rates are backwards?

[J. Fast]

Bent frame? lol

Unfortunately I can’t add much to this subject right now but I'm very interested in the info.

No man, this was on a racetrack. The suspension is not properly balanced. Not even remotely close. Look at the diagonals.



J what about the spring ratings on ECS struts, you thinking that the spring rates are backwards?

I don't think so. From most of my research what I've found is Evo's come stock with a similar front to rear spring bias (front higher sprung) as compared to the 3/S. But they've been significantly improved with an inverted spring bias (rear heavy sprung) and different valving.

EDIT: Many lower market Evo suspension retailers still sell shocks with high front and low rear spring rates. The pro's who own suspension tuning facility's will laugh at you when you discuss what you have on there. If the fronts are higher than the rears they know right out of the gate your suspension isn't setup correctly.

[2fnloud]

Well valving will not change, I am not willing to leave the ECS strut.

[J. Fast]

Well valving will not change, I am not willing to leave the ECS strut.

This friggin sucks man... Nowhere to get answers for stuff like this on our platform. No legitimate suspension shops that just just deal with suspension and have shock dynos. I'm totally in the dark :(

[2fnloud]

I would be totally willing to loan out my new in box struts if we had a dyno available

[J. Fast]

I'm sure Nascar shops are a dime a dozen in the Northeast. Anything close to you? I've been working with AMS trying to figure out what's going to work best for me if I want to go down the JRZ rabbit hole. It's looking like 14k rear and 11K fronts. If I throw a huge splitter on possibly 14K/14K (front/rear)?

[2fnloud]

nothing with in a 2 hour drive of my city

[KeithMac]

Are you trying to promote oversteer, neutralise understeer with the stiffer rear springs?.

[J. Fast]

Are you trying to promote oversteer, neutralise understeer with the stiffer rear springs?.

No, I'm trying to set the spring rate.




....Unlike the front strut which is pretty much mounted at the hub, a 5k spring rate in the rear does not mean a 5k rate at the wheelhttp://images.intellitxt.com/ast/adTypes/icon1.png (http://www.evoxforums.com/forums/showthread.php?t=66230#). Essentially the suspension arm is a moment arm....placing the spring inwards towards the pivot point means it needs to be stiffer. Sometimes you'll see people mention the "motion ratio." For the front EVO with the strut based suspension, it's close to 1 (almost). For the rear, it's somewhere between .6 to .9.

To get the "wheel" rate, you multiply the spring rate by the square of the motion ratio.

What he said here is... When the pickup point for the bottom of a rear strut is inboard from the rear hub assembly there's a pivot/moment arm which reduces the actual sprung weight at the wheel. You have to multiply the spring rate by the moment calculation in order to realize the actual rate. I would suspect that number is somewhere between .7 and .8 on a 3/S with Supercar Suspension Adapters. So a 12K rear spring actually behaves like a 9K in the rear once the moment reduction is realized.

In english... If you want 600lbs of spring at the rear tire you need like 800lbs of spring on the rear strut.

[J. Fast]

Contined... Since the front strut is inline with the hub and not offset... and the ratio is 1 to 1 then if you want 600lbs of spring at the wheel then you need 600lbs of spring. I believe that's the correct interpretation? Is that how that read guys?

[2fnloud]

That is how I would pick it up, but doesn't that same truth apply to the rear?

[DK77]

That's how I understood what you posted...

[J. Fast]

That is how I would pick it up, but doesn't that same truth apply to the rear?

No, it doesn't apply to the rear because the rear strut doesn't terminate at the hub. It's offset. The offset difference is a lever arm.

Think of it like a teeter todder. Say there's a 600lb weight on one end and a 300lb weight on the other. You can balance out both by moving the fulcrum. In an illustrative way the reduction is the distance moved from body center.

[2fnloud]

OK I thought it was really close to hub, my bad
'

[DocWalt]

As I've posted before, there's a shop 15 minutes from my house with a shock dyno. We need fittings made before I'm even going to call them, I'm not wasting my time nor looking like a fool when I can't come through.

[2fnloud]

I know, who can make the fitting? Jeremy could you make the fitting?

[anyonebutme]

Depending on how your top hats are set....front motion ratio is .93 to .98. Rear is like 1.2. I haven't finished measuring the rear yet. On rear your spring will be less than front on 3s for 99% of people.

[J. Fast]

Depending on how your top hats are set....front motion ratio is .93 to .98. Rear is like 1.2. I haven't finished measuring the rear yet. On rear your spring will be less than front on 3s for 99% of people.

Will this change depending on wether or not we utilize camber plates? Where are you and Andrew @ GT Worx deriving that rear differential number from?

I'm getting conflicting info regarding setting this up and it's really frustrating.

[DocWalt]

How is the rear motion ratio greater than 1?

[J. Fast]

What I've coming my way... JRZ Triple Adjustable. I bought them from a guy on Evo M.

http://img252.imageshack.us/img252/8610/dsc0030tz.jpg

[J. Fast]

I know, who can make the fitting? Jeremy could you make the fitting?
Make adapters for the shock dyno? I'm guessing this requires upper and lower front and rear adapters? I suppose I could make A-frames. What size hole at the top and bottom for mounting, 1/2"?

I'm not free this coming up weekend but next weekend. I can make something.

[DocWalt]

1/2" should work. Need to keep some method of allowing the wires for ECS to be connected. duke_3k (IIRC that's his username) offered an ECS controller to put the shocks into the correct valving positions.

[Erron Spalsbury]

Bent frame? lol

Unfortunately I can’t add much to this subject right now but I'm very interested in the info.

Hahahaha, well, maybe... It's from my car. Taken a few second from this pic...

http://imageshack.us/a/img841/3540/blue1w.jpg

This is from a friend (Ray's camera Jer)..
http://imageshack.us/a/img864/6268/img3947v.jpg

Lifting the rear inside tire is very common. This really isn't even the best pic. I have one at home that was during hard braking and transitioning into turn in where the rear is a good 5" off the ground. This is with the 14/10 front/rear setup. (787lbs/ 564lbs)

That's not anywhere near enough. That's why I recently switched to 1300 up front and 1100 in the rear. We'll see how that works this year because I was giving away a bit by lifting the tire that much. I had Hal machine me up some adapters to fit a proper 2.5" Hypercoil.
http://imageshack.us/a/img705/2864/coild.jpg


To be perfectly honest, I wanted a higher rate than even the 1300's. A few of the faster guys are in the 2000's for spring rates on a similarly weighted car.

[anyonebutme]

How is the rear motion ratio greater than 1?

Spring is behind the hub while the pivot is in front of the hub....so spring travels a longer distance then the hub. The evo mounts the spring to the control arm iirc, meaning its possible it has a Mr less than 1.

[J. Fast]

You can have JIC FLT TAR's Muellerized, E. He revalves them and puts a pretty hefty spring package on them. 14K in the rear and 11K in the fronts. I don't know where he's deriving his setup for Evo's and 3/S but the bias he AST, AMS, GT Worx, and JRZ are coming up with is way different. They're saying more spring in the rear if not equal to the rate of the front?

I'm trying to separate the music from the noise.

Wait, what? You think you're frame is bent Erron? Is that from the divider hop at 80, from the cage, something else, or are you just being silly?

[DocWalt]

Spring is behind the hub while the pivot is in front of the hub....so spring travels a longer distance then the hub. The evo mounts the spring to the control arm iirc, meaning its possible it has a Mr less than 1.

Pivot is that far out? It's been a long time since I've looked at the rear suspension in that much detail.

[J. Fast]

A few of the faster guys are in the 2000's for spring rates on a similarly weighted car.

Just thinking for a moment, 20K seems like a whole lot of spring for a 3000lb car. That's 1100lbs of rebound per spring on a corner. I bet it unloads aircraft style unless you have double that in aero to keep it planted. Doesn't sound achievable without a tubular or superbody chassi? What kinds of 3000lb cars are we discussing here? Unlimited's :p?

[anyonebutme]

Pivot is that far out? It's been a long time since I've looked at the rear suspension in that much detail.

Trailing arm suspension. It might be as low as 1.12....but its definitely >1.

[J. Fast]

Spring is behind the hub while the pivot is in front of the hub....so spring travels a longer distance then the hub. The evo mounts the spring to the control arm iirc, meaning its possible it has a Mr less than 1.

Isn't one of the major factors considered in calculating the motion ratio based off the inclination angle of the strut?

From what I'm reading from WORKS the motion ratio shouldn't be greater than 1:1 in the rear unless the top anchor and bottom anchor suspension mounts cast a projection line which falls inside of the tire patch. I don't think our cars do that. I think we have something like 12% on the projection angle and an additional 5-10% on the inclination angle which puts us in the .78:1 range in the rear?

I wish I knew wtf was right vs wrong so I could check my sanity and my wallet. How are you arriving at your numbers bro?

https://docs.google.com/viewer?a=v&q=cache:V9MU1DZn5GIJ:www.worksevo.com/Spring_Rates_1.pdf+calculating+spring+rate+motion+ ratio&hl=en&gl=us&pid=bl&srcid=ADGEESgvryDFUgrJaiwicNvnBaLJhMr2iN2nsHFvVVo7 wsC2SXinsSaAXDN7852Eze3_4guu1zfeaJxtSqbRzd76stTNnZ LzJYGO0rurbf2vkzhuUa7sLMC90G5pQd2MIPM5RC169Xp1&sig=AHIEtbQYZsONvmJL6OvikUCy9S9wqNxcnw

[Erron Spalsbury]

Just thinking for a moment, 20K seems like a whole lot of spring for a 3000lb car. That's 1100lbs of rebound per spring on a corner. I bet it unloads aircraft style unless you have double that in aero to keep it planted. Doesn't sound achievable without a tubular or superbody chassi? What kinds of 3000lb cars are we discussing here? Unlimited's :p?

Hahaha, I was just being silly about the bent frame comment.

A number of the Vipers are in the 2000lb spring range. I think if you ask around you'd find a lot of the faster cars are way up there in spring rate.

I had my buddy (the other Jake) take a ride with me and help setup the suspension. This is the driver I just posted over the weekend that took 5th in F1000 down at COTA that I sponsor. A super great guy that you have to hang with. I raced with him for a few years through the SCCA. In a brief nutshell you just want the suspension to not bounce on rebound. A nice compression with a swift rebound without any oscillation or hop. (higher dampening rate will slow this) I'm honestly a little worried about how long the JIC's will be able to take this amount of spring since it's darn near twice what they had in mind when they made them. I'm two clicks from maximum on the front, rears are one click of the bottom, but I don't want max. I want it to be able to absorb at a fast rate but not not be so stiff that it doesn't have time to absorb. Basically, the lowest setting possible without any bounce.

Some say..."you can never have enough spring". But I think that was from a kart driver. :P

[anyonebutme]

Isn't one of the major factors considered in calculating the motion ratio based off the inclination angle of the strut?

From what I'm reading from WORKS the motion ratio shouldn't be greater than 1:1 in the rear unless the top anchor and bottom anchor suspension mounts cast a projection line which falls inside of the tire patch. I don't think our cars do that. I think we have something like 12% on the projection angle and an additional 5-10% on the inclination angle which puts us in the .78:1 range in the rear?

I wish I knew wtf was right vs wrong so I could check my sanity and my wallet. How are you arriving at your numbers bro?

https://docs.google.com/viewer?a=v&q=cache:V9MU1DZn5GIJ:www.worksevo.com/Spring_Rates_1.pdf+calculating+spring+rate+motion+ ratio&hl=en&gl=us&pid=bl&srcid=ADGEESgvryDFUgrJaiwicNvnBaLJhMr2iN2nsHFvVVo7 wsC2SXinsSaAXDN7852Eze3_4guu1zfeaJxtSqbRzd76stTNnZ LzJYGO0rurbf2vkzhuUa7sLMC90G5pQd2MIPM5RC169Xp1&sig=AHIEtbQYZsONvmJL6OvikUCy9S9wqNxcnw

I'll expand when I get home....we don't have struts in the rear. Look at it from the side not the rear.

[J. Fast]

Trailing arm suspension. It might be as low as 1.12....but its definitely >1.


I'll expand when I get home....we don't have struts in the rear. Look at it from the side not the rear.

Gotcha, please elaborate! This would be good to know!

Setting up suspension needs to be sticky type stuff!



Hahaha, I was just being silly about the bent frame comment.

A number of the Vipers are in the 2000lb spring range. I think if you ask around you'd find a lot of the faster cars are way up there in spring rate.

I had my buddy (the other Jake) take a ride with me and help setup the suspension. This is the driver I just posted over the weekend that took 5th in F1000 down at COTA that I sponsor. A super great guy that you have to hang with. I raced with him for a few years through the SCCA. In a brief nutshell you just want the suspension to not bounce on rebound. A nice compression with a swift rebound without any oscillation or hop. (higher dampening rate will slow this) I'm honestly a little worried about how long the JIC's will be able to take this amount of spring since it's darn near twice what they had in mind when they made them. I'm two clicks from maximum on the front, rears are one click of the bottom, but I don't want max. I want it to be able to absorb at a fast rate but not not be so stiff that it doesn't have time to absorb. Basically, the lowest setting possible without any bounce.

Some say..."you can never have enough spring". But I think that was from a kart driver. :P

Lemkuhl... Formula guy? We've met. I've seen his new toy on FB and seen him comment on Racing Tech Tip's every once in a blue moon.

I can't answer this stuff E, only comment on what's out there. It's a little outside of my knowlege ATM. I'm learning quickly tho. I will have my mind and hands wrapped around it real soon (I might even visit Claude Rouelle and see if he can squeeze me in since he's across the way).

From what I'm hearing and reasearching so far regarding spring rates it's the other way around. We want the least amount of spring that which promotes the best tire contact in all situations. If we were on a flat track at max speed like in Nascar then big spring, yes. Autocross, where you can jack a suspension and go two wheeling, yes. Since were in compression and rebound and pitch and roll and speed and comfort is more about tires staying planted, then we want les spring and better shock valving.

It sounds like it's very difficult to keep a chassi settled with a huge spring. From most of what I can find the highest spring rate for an Evo which is quite comparable to ours is a 700lb spring. That's on a world championsip vehicle or something like what Dave K drives.

[Erron Spalsbury]

No, that's THE Jake, this is the OTHER Jake.
Jake Latham - Yep. (http://www.jakelatham.com/)

Allow me to toss out a few thoughts and a comment.
How hard is it to keep a kart chassis settled? (ie. no springs) I realize these are worlds apart but there's some knowledge there than can transfer over. For instance, how do you hold the most grip in a kart? By allowing your body to transfer to the outside of the seat or weight transfer in general. The top kart guys will you tell you they literally lean OUT in a corner and even do so before the corner to have the weight where it needs to be during the initial "bite" or turn in. So transferring weight needs to be quick and concise. If you're waiting to bound up a spring and for the car to physically lean out you've lost time. (see what I'm trying to convey?) This is a fun one to do in a parking lot. Give the wheel a solid, quick crank in one direction or the other at say 30mph and you'll see the delay I'm referring to.

The big key here isn't what "should" work best, it's what does, for how you drive your car. I lift that inside tire on every corner, left or right. Think about the trophy photo in my office you've seen. The left rear is way off the ground. I'm giving up traction for sure. Now if I hadn't braked as late or snapped into the corner as hard I probably could have carried more speed. In the heat of the moment though, I drive. I obviously have something to gain by going to a higher spring rate. Not all will, but a lot do. :) This is why I went with an easily swap-able spring like the Hyperco's. I have a ton to choose from for not a lot of money. If it doesn't work the way I want it to, a couple hundo later and it's a whole 'nuther car.

The 1100's I have for the rear are 2.5" but they are actually Eibachs that came off of Philip's at SCE car. He said it made the car feel "twitchy". I LOVE the twitch. Small inputs make the car turn and turn like, "Holy crap, I was only thinking about turning and now I'm turning!" kind of thing. Har-har-har-hootenanny-gigity!

[CoopKill]

Awesome stuff. Here to suck up the knowledge.

[green-lantern]

Hahahaha, well, maybe... It's from my car. Taken a few second from this pic...

http://imageshack.us/a/img841/3540/blue1w.jpg



lol I'd be afraid to see my car. might be like 3000, 25, 300, 10. lol

[anyonebutme]

http://img.photobucket.com/albums/v55/PrestoTuna/MSPaint%20stuff/MR_zpscbc9e763.jpg

just a rough measurement from my spare subframe. The actual control arms are for locating and camber curves, and have no effect on the motion ratio of our multi-link trailing arm rear suspension. The above quick measurement assumes straight vertical shock, which is really isn't but it's close enough for making the point.

Circle far left is the pivot, large circle is the hub/wheel center, right is lower shock mount bolt.

[J. Fast]

http://img.photobucket.com/albums/v55/PrestoTuna/MSPaint%20stuff/MR_zpscbc9e763.jpg

just a rough measurement from my spare subframe. The actual control arms are for locating and camber curves, and have no effect on the motion ratio of our multi-link trailing arm rear suspension. The above quick measurement assumes straight vertical shock, which is really isn't but it's close enough for making the point.

Circle far left is the pivot, large circle is the hub/wheel center, right is lower shock mount bolt.

From what I've been told by Andrew we should measure the actual on the vehicle and not use the assumed lever method becuse this will give us actual vs. assumed measurements and estimated angles.




J,

Measure the motion ratio at the tire contact patch. This is what the tire actually sees. This is how you calc it.

1. Take a measurement from the center of the rear axle to the fender at resting ride height.

2. Jack up rear end and unload the springs by loosening the ride height collars so you can adjust the suspension thru tension and compression freely.

3. Place jack under tire and jack tire to resting ride height and measure the distance between the fender and the center of the tire patch.

4. Adjust jack under tire and lower tire to 1" below resting ride height and measure the distance between the spring perches. This distance is referenced as "Distance Below" or D(b).

5. Adjust jack and reset ride height to 1" above resting ride height (jack up tire 2" from D(b)) and measure distance between the spring perches. This distance is referenced as "Distance Above" or D(a).

Now calcualte the installation ratio which is: ( D(b) - D(a) ) / Distance between tire contact of D(b) and D(a)


Square the resultant of the installation ratio and your answer is the Motion Ratio.

[anyonebutme]

Yes that's more accurate, but the point is it's still going to be >1

[J. Fast]

Yes that's more accurate, but the point is it's still going to be >1

So the motion ratio is licked, excellent! Now we just need to know the exact motion ratio number so we can calc the actual spring rates at the wheel. Anyone have a jackstand, jack, some coilovers mounted, a spanner wrench, and a tape measure handy?

[anyonebutme]

Give me a day or two to switch cars in the garage if nobody bites.

[GTOJOE]

A lot of this is over my head but I did have a conversation here with a guy that races his GTO very competitively and one of the things he eluded to was that the rear spring rate needs to be stiffer than the front. He has modified almost every part of his car including modifying the aluminium front subframe from an awd Magna here in Australia and fitting it to the GTO. He also said the lower control arm mounting points on our cars are too low so when the car is lowered the arm sits almost horizontal when it should still be sitting with a more downward angle towards the wheel/hub. He drilled new mounting points for the control arms about an inch above the factory one on the rear and mounted them there. He then had to get the adjustable 3sx camber arms bent to the right shape so they don't hit the body. The front mounting points was resolved with the new sub frame he installed. To top it off he has spent crazy money on fully adjustable coilovers with external reservoirs from Japan. I can't recall the brand though. MichaelMR2 was there also so maybe if he reads this he will remember the brand.

[J. Fast]

A lot of this is over my head but I did have a conversation here with a guy that races his GTO very competitively and one of the things he eluded to was that the rear spring rate needs to be stiffer than the front. He has modified almost every part of his car including modifying the aluminium front subframe from an awd Magna here in Australia and fitting it to the GTO. He also said the lower control arm mounting points on our cars are too low so when the car is lowered the arm sits almost horizontal when it should still be sitting with a more downward angle towards the wheel/hub. He drilled new mounting points for the control arms about an inch above the factory one on the rear and mounted them there. He then had to get the adjustable 3sx camber arms bent to the right shape so they don't hit the body. The front mounting points was resolved with the new sub frame he installed. To top it off he has spent crazy money on fully adjustable coilovers with external reservoirs from Japan. I can't recall the brand though. MichaelMR2 was there also so maybe if he reads this he will remember the brand.

This stuff may sound complicated but it's actually really easy once we sifted thru all the garbage. The easy part comes when we take actual measurements off a TT 3/S GTO and determine the motion ratio. Once we know what that is we'll simply multiply our spring rates by that number and it will spit out the wheel rates. We'll look at the corner weights which tell us the front requires springs which couple eachother and at a minimum can redistribute 1000lbs dead and whatever dynamic bias comes from the front to rear and diagnals. Something like a 650lbs spring is good for this.

As for the rear, we see a coupled weight of 650 at the corners but a hidden weight from rear wing aero which in my case at speed equates to roughly 500lbs. If that's the case then my rears need to handle a coupled rate of 900lbs. A wheel rate in this case might be 600 for the rear. But depending on what the motion ratio is the actual spring rate might be 800lbs or could be as low 500lbs depending on the motion ratio value in the rear being more or less than 1. Less than 1= more spring. More than 1=less spring.


If we know our ride frequency is say 2.0Hz and we want 6XXlbs of sprung weight at all corners we just fit springs that index that amount when multiplied by motion ratio and ensure the valving adjustment is setup for the freq/oscilation and so forth.


A little hint here of things to come, the additional considerations are based off additional weight added to the chassi based on aero and lateral/front/rear bias and lateral G forces required to keep the tires planted and maintain tire contact. Fast = tires staying in contact with road surface and when you come under tension or compression you come back to neutral with minumum attenuation/vibration. When the road surface changes we don't want to bounce or bottom out or hop. We want to stick, like when a Mickey Thompson Truck goes over whoop-de-doos. The tires stay in contact with the road surface and the body stays quiet and doesn't move. When they jump they land, attenuate, and stick. They don't bounce at all.

The secret sauce in this stuff does not require a ton of spring. It requires maximizing shock travel. The more room you give the shock/springs to absorb road surface imperfections and obstacles the less bounce and rebound we experience.

In your frineds case, sometimes you have to move pickup points to give the suspension more room to travel and correct tire contact.

[Erron Spalsbury]

Right, now couple that with the compression of acceleration and braking loads and you might be some where in the ball park. Doing the calculations will get you about 60% of the way there. The best way is with a potentiometer or the old school method of a zip tie.

[DocWalt]

Old school? The ziptie method is still the name of the game for everyone except top tier teams in motorcycles or mountain biking :p

[Erron Spalsbury]

Old school? The ziptie method is still the name of the game for everyone except top tier teams in motorcycles or mountain biking :p

Ya, what we call BT. Or, before telemetry.

Now's there's a few nicer ways to do it. Ie...
http://imageshack.us/a/img834/853/77871052282846774755818.jpg

[DocWalt]

Of course there's nicer ways to gather data, but how many 3S owners have that kind of cash laying around? ;)

[SUTHNR]

Good discussion on the front/rear differences.... but I am wondering, since our cars display such a left/right variance, shouldn't the left and right sides, particularly in the front, run separately/differently weighted springs?

EricB

[vr4tune]

Good discussion on the front/rear differences.... but I am wondering, since our cars display such a left/right variance, shouldn't the left and right sides, particularly in the front, run separately/differently weighted springs?

EricB

my best guess would be, that the GTO is RHD in Japan the left side bias is compensated by drivers weight. The block being 6 cylinders and cast iron offsets the weight to the left side. I assume that's the reason for the Japanese puting the engine on the left side rather than the right side. This counter balances the driver on a RHD GTO. We got screwed being LHD in the states. I think that a 150-200lbs man sitting on the right hand side would be about perfect for weight distribution.

[vr4tune]

If you buy a set of Meullerized DFV's for a 3000gt (which they make now BTW) that's how John Meuller reccomends they come. More spring in the rear. However, you can custom order them however you want. ;)

Tooner shocks are doing it wrong.


I know they make them, Nate's planning on buying a set.

I wouldn't be at all surprised if the "tooner" companies got it wrong, FWIW.

Looks like evo suspension to me!




Description: Muellerized Ohlins Coilovers adapted for 3000GT VR4 & Dodge Stealth R/T with John's custom specifications. We setup/tune each suspension to match each individual customer's application. Installation not included. Additional hardware required (see below).
Suspension Price: $3,199
Adapter Brackets: $200
Hardware: $25
Total: $3,424
NOTE: 1.5 hour of assembly labor is additional as Ohlins come disassembled with most parts individually sealed/packaged.
NOTE: Slight modification to mounting points is necessary in front.


Welcome to Muellerized Suspension Systems (http://www.muellerized.com/products_3000gt.html)

[MR2]

see, you guys do it all wrong Imperial and LHD :p

[J. Fast]

Alright guys, I'm working on setting up a baseline measurement on a Tein adjustable setup. Should have some hard data on this by this weekend if my scheduling can stick.

What I'm curious about at this point is if we have a stock ride height and we measure the shock travel at M(b) and M(a) with a travel of 2" will the indexed motion ratio be equal to one with a 2" drop? I'm suspecting the motion ratio is non linear as the upper pickup points move closer to the lever. Ofcourse this is just a hunch, the math will tell the story.

As far as balancing out the corners? My thinking is unless wr require bias because of a banked road surface, or predominant turns, the corners should atleast have diagonals within a very small percentage of one another. That's why you take your vehicle to a pro shop to set your suspension. The weight imbalance can often be resolved with spring preloads and ride height adjustments. Should that not be the case we'll atleast have a pro opinion on where things need to move to improve the setup. Truth be known, I've never seen a professionally tuned suspension not balanced on the diagonals. What I have seen is varied spring rates on all corners.

[sergechronos]

Ofcourse this is just a hunch, the math will tell the story.

Since when has math ever solved anything for anyone? :P

Incredibly interesting discussion, very eager to see what data comes up. Varied spring rates on the corners makes sense to a degree, although having ridden in a few Evos with coil over set ups, I have to wonder how these rates will translate to actual road use. A friend with an Evo 9 has found his coil overs to be rather unstreetable with potholes and such on actual roads, and I tend to agree with him that it makes it feel a bit too much like a go-kart for actual road use. So I presume most of you guys are looking at this for track/auto-x purposes?

[anyonebutme]

Since when has math ever solved anything for anyone? :P

Incredibly interesting discussion, very eager to see what data comes up. Varied spring rates on the corners makes sense to a degree, although having ridden in a few Evos with coil over set ups, I have to wonder how these rates will translate to actual road use. A friend with an Evo 9 has found his coil overs to be rather unstreetable with potholes and such on actual roads, and I tend to agree with him that it makes it feel a bit too much like a go-kart for actual road use. So I presume most of you guys are looking at this for track/auto-x purposes?

Coilovers don't automatically mean shitty ride. Its just spring rate and damping matching. If his coilovers ride like ass it means the springs or damping rates don't match what he wants.

[MR2]

ECS is best :p

[sergechronos]

No coil overs don't mean a shitty ride necessarily, but with the rates he runs and the rates under discussion here, it is similar and both would be very stiff springs indeed. My question was more one of would this knowledge still be applicable to the rest of us if we reduced spring and dampening rates down 10-25% (which are probably still significantly stiffer than factory) so long as the ratios between the corners is the same?
Example: Car weighs like the one previously listed at
1082 893
586 752

Spring rates found to be appropriate are (as an example) let's say
12k 11k
13k 14k

Could those numbers be reduced by a percentage, thus keeping the ratios fairly similar and compromising on the bleeding edge of performance (but still markedly better than most suspension options currently) but allowing a more streetworthy ride? Say a 25% reduction (which would probably still be significantly stiffer than factory)
9k 8.25k
9.75 10.75k


Given most of our coil over and spring options now are, as pointed out previously in this thread, stiffer in the front than the rear while more modern suspension concepts for the Evo have reversed that and made the rear stiffer than the front. What I'm looking at is with this change to a stiffer rear set up, as well as a particular spring and dampening rate that is set up for our cars explicitly for tracking purposes, could be adjusted either via spring rate or dampener force to maintain the vast majority of that performance increase while being a bit more usable in regular driving.

Short and dirty of it: of how much value is this information going to be to the 3/S community who can't afford to spend 3k+ on suspension? Given that manufacturers are unlikely to change their spring rates just on our calculations, would these calculations and rates be able to be applied to some degree for the rest of us by getting springs that are closer to the ideal spring rates J is working out, or would it be so little of a difference versus off the shelf suspension options not to be worth the cost?

[CoopKill]

Also realize that J may have a 15-25% weight reduction, so his rates would give a stock weight car exactly what you are asking. The answer in short is yes. The closer to optimal spring weight, the better performance can be had. Where things may get sticky is with the valving vs. spring weight vs. car weight.

[sergechronos]

Also realize that J may have a 15-25% weight reduction, so his rates would give a stock weight car exactly what you are asking. The answer in short is yes. The closer to optimal spring weight, the better performance can be had. Where things may get sticky is with the valving vs. spring weight vs. car weight.

Oh no doubt, not even a comparison between the average 3/S and his in terms of weight. However, if what he finds holds true for the platform as a whole, then SCE might see more usage of their Evo adapters and us raiding EvoM for used coil over set ups that have rates closer to our needs, or maybe someone tracks down (or does the math) for springs that will bring the cars much more in line with the ideal. Since all suspension options for the car currently (just off hand) have stiffer springs in the front, or no listed rate for it. The Megan coil overs for instance have a 12k/8k set up, and even the Apex'i S1 that is allegedly better for the US roads uses 8k/6k set up. So this would require either new products that recognize the benefit of the stiffer rears, or a raiding of Evo parts.

[2fnloud]

Or try Tein pillow-mounted ECS Struts with Ground Control sleeves with spring rates that balance out:

corner weight info:
ride hight
ect
ect.

[J. Fast]

This post right here is absolutely brilliant and will save me hours of my life in explanation...

Selecting Spring rates for coilovers. Theory and How to (http://9glancers.com/index.php/topic,13730.msg199890.html?PHPSESSID=121790092a771 9cee0a9927371439f77#msg199890)


I'm writing up another one of my little bits that provides some math, some questions, and hopefully some answers. This time I will be talking about suspensions - spycifically choosing spring rates for your coilovers. I know BC Racing lets you choose your spring rates for a fair price, but have not heard about other companies offering this same service.

Now, the only spring rates posted for coilovers that I've thus far been able to find are BC (8k front and 6k rear) and Megan (8k front and 10k rear). This is what really peaked my interest two different companies producing their springs at the exact same plant with the exact same front rates, but one is producing springs 2k stiffer in the rear and one is producing springs 2k softer in the rear. So my question is which one theoretically would provide better handeling for our car?

Now, I know the BCs are a better quality (read larger monotube) than the Megans, and I've only heard good things about the BCs and mixed reviews about the Megans - most people find the megans too stiff, and a little bit low in quality for their purposes, but this isn't a discussion about brand names rather we're here to select spring rates.

I previously had asked this question in a couple other threads because I've always heard you want to stiffen the suspension in the rear to reduce understeer (which we have pleanty of) and was told at the time that the BCs would still be the way to go despite the softer rear spring rates because there is less weight in the rear so it works out.

I still wasn't completely satisfied so I did a little bit more research and here's what I have come up with: Take it as a grain of salt because I'm still a newb, this being my first car worth modding, and feel free to provide constructive feedback if I've gone off course anywhere. Without further adeau:

The first thing you want to do when setting up a suspension is to decide on your ride quality aka stiffness. The easiest way to compare the stiffness of a car across platforms seems to be by looking at the natural frequency of the cars suspension measured in hertz (cycles per second) this would be how fast the car bumps up and down when you continually press down and release on it. As a general rule of thumb it seems that around 1 HZ is standard for OEM 1.5 HZ is what a good sports car runs and 2+ Hz is typical for race/track cars. Just to give you an idea a stock STI natural frequencies are 1.6 Hz front and 1.8 Hz rear so if you've driven one of those you know about how rough/smooth these ranges are.

For my setup I'm sort of the weekend warrior who likes to take a couple corners/canyon drives a little more agressive and doing about 1 track or autocrosse a month so I wanted to end somewhere between a sports car and a track car so I'm going to be shooting for 1.75 Hz on my setup and just deal with a little bit rougher ride on my daily driving.

The equation I found to calculate the wheel rate is WR = (Wheel Frequency/187.8 )^2 * Sprung Weight

I found the curb weight to be 3010 lbs for the manual GTS so when you throw my fat butt and a little gas in there I decided to base my weight estimates on 3333.3 lbs for the car.
The GTS manual has a 60/40 front/rear split for weight distribution, and in my newbness I forgot to subtract the unsprung weight (usually 80-90 lbs per corner). I also assumed that the weight balance left to right was equal. I chose these numbers to make my calculations a little bit easier so the weight on each of the front springs is about 1000 lbs, and each of the rear tires is 2/3 of that or 666.6 lbs.

To do this for a real suspension setup you would want to get corner weight scales and measure the actual weights on each tire. These weights may also change if you use your coilovers to adjust the height of each corner (higher=more weight on that corner). I also assumed an equal drop all the way around which would keep the 60/40 split. Ideally you would want to adjust the heights and weights (relocate battery etc.) to get as close to 50/50 as you can.
You will also have to convert the frequency you desire from Hz to cycles per minute for the given equation (multiply by 60)

Plugging some numbers into the equation for the front tires you find Wheel Rate = (105/187.8 )^2 * 1000 = 312.6 lbs/inch = 5.551k
Now, if you were to take the rear through the same process you would get 2/3 of the wheel rate which is pretty close to what BC is employing with their 8k/6k springs (2/3 would be 8k/5.3k)
But there are an additional couple of equations to consider.

The first is that you don't want the front and rear suspensions to have the exact same frequency. This would create oscillations (bouncing up and down) from the front to the rear. Generally it is accepted to stiffen the rear 10-20% to combat this.

Lets take it a step further and tune in exactly how much stiffer we want the rear than the front. This is going to involve a little more math so hang on.
When coming upon a bump the front tires will hit it first and the rear tires will hit it second. A little trick is to have the car settle at the same time for a smoother ride. Exactly how far appart do they hit? We'll need to figure that out for a predetermined speed. I'm going to use 70 mph since that is my typical cruising speed.

Now, the wheelbase of the GTS is 103.7 inches = 8.64 feet. At 70 mph you are traveling 102 ft/sec so it will take you .085 seconds from when you hit the bump with your front tires to when you hit the bump with your rear tires now we need to make them settle at the same time.

To do that we actually are going to increase the frequency of our reas suspension (remember how the subaru had 1.6 Hz front and 1.8 Hz rear) to find out exactly how much we're going to take our front rate and tune that in for the rear wheel rate. So we invert 1.75 to find our front takes .5714 seconds per cycle, subtract the .085 seconds difference to find our rear rate will be .486 seconds/cycle and invert that again to get 2.06 Hz (track car rates here people)

Now we'll plug these numbers into our equation from before to find the rear wheel rate = (123/187.8 )^2 * 666.6 = 285.9 lbs/inch = 5.078k (nearly equal front and rear rates even though the back end is lighter. This will definately help us eliminate some of that understeer)

But we're still not done. You might have noticed I said wheel rates, but what we're looking for are spring rates. There's one more step before we can know the spring rates, and unfortunately I do not have an accurate measurement to base these values off of. The question is called motion ratio aka when the wheel moves an inch how much does the spring move?

Macphearson suspensions (which our front suspension is) generally have a motion ratio of 1:1. Meaning when you push the spring down one inch the wheel moves one inch. The back suspension, however, is multilink and this is where I don't have accurate numbers. I've read that the motion ratio of the rear suspension is anywhere from 1:.9 to 1:.6. This means That for every inch the wheel travels the suspension actually travels less.

Let me explain why this matters so much. What we have found so far are the wheel rates aka how many pounds of force will cause the wheel to move one inch. When you put the wheel further out than the suspension and do not place it at the proper angle you give yourself a lever so you need a stiffer suspension to counter this fact. The textbook example would be a wheelbarrow. To lift a rock that is 100 pounds one inch with your hands you have to lift with 100 lbs of force for one inch. To lift a 100 lb rock one inch with a wheelbarrow you will have to lift with less force (maybe 25-50 lbs) over a further range of motion (2-4 inches). This is essentially what we need to do with our suspension. We want to lift with 100 lbs one inch at the end of the wheelbarrow. To do this we would need to put a heavier rock in the wheelbarrow (200-400 lb.) and lift the rock only half as far (1/4-1/2 inches).
This is the equation that will help us to solve for our spring rates: SR = Wheel Rate * Motion Ratio^2

I plugged in a dummy value (1:.85) to finish off my calculations, but if somebody would be willing to measure these values that would be great since my wife has the car. The easiest way would be to measure the wheel and suspensioin on the ground then jack it up and measure how much the spring changed and how much the wheel changed. I think ebiach also had a tutorial online that involved distances from the suspension and the hub where the wheel contacts the ground and the angles and a ratio between the distances, but my way is easier and doesn't involve eyeballing it.

Contunued...

[J. Fast]

...Continued from above

To finish off:
Spring rate = Wheel Rate * Motion Ratio^2
Front = 5.551k * 1(ish) = 5551 kg/m
Rear = 5.078k * .85^2 = 7028 kg/m

So, based upon those results it seems that the Megans are set up for a more neutral stance though understandably they would be quite firm. The BCs appear to be set up to leave some of the stock understeer in the vehicle, but if you're increasing the rake of your vehicle they could prove to be a very potent setup nonetheless. Either way I've read that their damper fine tuning provides approximately +-2k adjustability so theoretically the Megans could be set up to be 10k up front and 8k in the rear or the BCs set up to 6k up front and 8k in the rear if you went full soft and full hard on the opposite ends to essentially switch their values. hence the value of a coilover setup.

Now, like I said I'm still a newb and have never set up a suspension before and fining the motion ratio will be critical to fiding accurate spring values because if it is closer to .6 then you might be looking for a suspension setup with 12k in the rear (remember the wheelbarrow example).

So what set is best? well it's all up to personal preference. 3 different professional drivers in the same car would prefer 3 different setups and could achieve very similar times.
As for myself I think 6k up front and 8k in the rear would be a pretty good setup for myself assuming I keep the stock rake, but I would imagine I will probably try to redispurse the weight a little bit better in a year or two when I actually will be buying my own suspension setup; I may even end up in a 7k/7k setup with a 50/50 weight distribution and some good lightweight parts; who knows, but it's all up to you and your preferences.

Also on a side note are there any other companies that let you choose your own spring rates?

Hopefully this will help you in selecting your own coils, but like anything else on the internet take it with a grain of salt. Sorry it was such a long post. I'm an engineer and tend to get carried away in theory and design. Good luck and cheers!



Note in this explanation how the corner weights being discussed are uniquely similar to the referenced 3/S corner weights. 1000lbs in the fronts 660lbs in the rears :).

[2fnloud]

Awesome info, will read completely...now your 1000 front and 660 rear.

For what struts?
How much drop in ride height?
Other factors that decide on the rates that you listed?

[J. Fast]

Awesome info, will read completely...now your 1000 front and 660 rear.

For what struts?
How much drop in ride height?
Other factors that decide on the rates that you listed?




Spring Rate


kg/mm
3
4
5
6
7
8
9
10
12
14
16
18
20
22
24
26
28


lb/in
168
225
281
337
393
450
506
564
674
787
899
1012
1124
1232
1344
1456
1568





Let's see here, assuming proper corner balancing and a speed of 70mph, Known Front Motion Ratio of 1:0.98, Rear Motion ratio of 1:0.84 @ 2" drop and MR of 1:0.86 at stock ride height. Estimated 600 lbs rake/frontal downforce and 500lb downforce in rear.

1. Stock 3/S Ride Freq of 1.60Hz corners weights of 1270lb fronts, 720lb rears
2. Stock 3/S Ride Freq of 1.75Hz w/1.25" drop, corner weights of 1270 fronts, 720lb rears
3. Modified 3/S Ride Freq of 2.05Hz w/1.5" drop, corner weights of 1000lb fronts, 650lb rears
4. Because Spec Racecar 3/S w/ Ride Freq of 2.2Hz w/2" drop, corner weights of 965lb fronts, 585 rears

Wheel Rate = ((60(Hz))/(187.8))^2 x (corner weight)

1. Wheel Rate:

FRONT ((60(1.6))/(187.8))^2 x 1270= 332lb
REAR ((60(1.87))/(187.8))^2 x 720= 257lb


2. Wheel Rate:

FRONT ((60(1.75))/(187.8))^2 x 1270= 397lb
REAR ((60(2.02))/(187.8))^2 x 720= 300lb


3. Wheel Rate:


FRONT ((60(2.05))/(187.8))^2 x 1000= 429lb
REAR ((60(2.32))/(187.8))^2 x 660= 363lb


4. Wheel Rate:


FRONT ((60(2.2))/(187.8))^2 x 965= 475lb With Aero: FRONT ((60(2.2))/(187.8))^2 x 1265= 625lb
REAR ((60(2.47))/(187.8))^2 x 585= 364lb With Aero: REAR ((60(2.47))/(187.8))^2 x 835= 519lb


Spring Rate = (Wheel Rate) / (Motion Ratio)^2

1. Spring Rate:


FRONT (332)/(.98)^2= 346lb
REAR (257)/(.86)^2= 347lb


2. Spring Rate:


FRONT (397)/(.98)^2= 413lb
REAR (300)/(.86)^2= 405lb

3. Spring Rate:


FRONT (429)/(.98)^2= 437lb
REAR (363)/(.84)^2= 514lb


4. Spring Rate:


FRONT (475)/(.98)^2= 494lb With Aero: FRONT (625)/(.98)^2= 651lb
REAR (364)/(.84)^2= 515lb With Aero: REAR (519)/(.82)^2= 735lb



According to the ref table above it's looking like beacuse racecar wants... 11K fronts and 13K rears.

I'd say GT Worx and Meullerized are about spot on with the bias.

That's enough for today.

[DK77]

Wait, when did we determine that the motion ratio was for sure less than 1?

[J. Fast]

Wait, when did we determine that the motion ratio was for sure less than 1?

Yep, I measured today :).

And for giggles in the archives...



I addition to spring rate, wheel rate is also a factor. I'm not as much of a suspention guru as DG but wheel rate is MUCH MORE important than spring rate. Natrual frequncy is the most important, as is takes more things into acount, but wheel rate might be a bit easyer starting point.
Wheel rate is the effective force of the spring on the wheel with the mechanical advantage of the suspention taken into account.
On a 3S the rear wheel rate is over 1. The spring is acted upon using a third class lever. Spring---- wheel---- pivot. The spring travels a longer distance than the wheel, so the effective rate is higher.
On a 3S the front wheel rate is less than 1. The spring is acted upon using a second class lever. Wheel ---- spring---- pivot. The spring travels a shorter distance than the wheel, so the effective rate is lower.
For EVO's the front AND rear wheel rates are LESS than 1.
So to sum it up, even though the spring rate is diffrent, it doesn't mean the effective force is different, since the mechanical advantages are different.

*sigh*


On a 3S the rear wheel rate is over 1.

No, it is not.
Unless you are looking at a pushrod/pullrod suspension with a ratio-changing rocker in it - which if you look at page 3-6 of the 3000GT Tech Manual, it clearly is not - the only way to get a motion ratio greater than 1 is to mount the shock/spring outboard of the wheel. That might be difficult to package.

Think about it - the load is outboard of the spring. What class does that make the lever?
My rough eyeball puts the rear motion ratio around .8 +/- .075 or so. Front motion ratio, being a McStrut, will be .98 -0.1.
Once I find time to model the suspension, I'll know for sure.

Only as a stepping stone to natural frequency.
Which is stiffer, a Lotus Elise with a wheel rate of 500 ls/in, or an F350 with a wheel rate of 750 lbs/in?
DG

[MR2]

I'll tell DG what's Stiffer.

[J. Fast]

I read your post in chat MR2 regarding the rates being really high. I think you're interpreting them wrong. The actual wheel rate of my setup based on the mechanical reduction is 11K Front's and 9K rears. That's the line called wheel rate.

The spring's I require multiplied by the motion ratio in order to obtain those wheel rates are 13K rears and 11K fronts.

The "Ideal Wheel Rate" for a stock 3/S is 6K front's and 4.5K rears. The actual spring rates required to achieve the ideal are 6K front and 6K rear.

Notice how this scale is not linear.

[DK77]

Hmmm... so is the pivot in front of the wheel or straight inboard from the wheel? Seems to me it's a little of both.

[J. Fast]

When you jack your wheel up unsprung from resting... when you raise the tire 1" does the shock travel more or less than 1"? There's your answer.

[MR2]

ahhhhhhhhhhh 6k and 4k, that's better :) I kept the rears and had double progressive 300lb front's put in, have not spent enough time playing with the valving to see if I like it or not

[DK77]

When you jack your wheel up unsprung from resting... when you raise the tire 1" does the shock travel more or less than 1"? There's your answer.

Fair enough. Glad we're dealing with actual measure values rather than assumed ones :)

[J. Fast]

Where this gets interesting... say you know 3/S rear shocks have 4" of overall travel from stop to stop. When we lower the chassi via lowering springs 2" we automatically think we have 2" of shock travel remaining... we actually have just shy of 2.5" because of the motion ratio.

[IPD]

subscribed. interesting reading so far. is 1.6 hz the stock 3/s rate for ECS on the hard setting, or the stock rate for non-ecs? where does n/a fall into that?

my butt doesn't seem to like much past 1.6hz--at least not for a car that sees daily use.

can we also infer that my wife's 03 sonoma crew cab is .5hz..since it's floaty as hell?

[mehrshadvr4]

Where this gets interesting... say you know 3/S rear shocks have 4" of overall travel from stop to stop. When we lower the chassi via lowering springs 2" we automatically think we have 2" of shock travel remaining... we actually have just shy of 2.5" because of the motion ratio.
weren't you going to make tube subframe for your car? these specs won't apply to your race car anyway.

[J. Fast]

... these specs won't apply to your race car anyway.

Sure they will. If anything what I will be gaining is shock travel. The adjusters I've selected have an adjustment range of an additonal 100lbs (2K). When I add a little camber, change caster and change the lever the motion ratio will change to about 1:0.8 ish give or take. I'll have plenty of valving and spring preload for the fine tuning. I can add more spring weight in but it's really difficult to take it out.

[2fnloud]

Jeremy thank you for finding and sharing this info....I think I can FINALLY order mt G/C sleeves for my ECS struts.

[Erron Spalsbury]

Are we having fun yet? Lots of good stuff in here and here's a whole lot more for ya'll to chew on...

http://www.optimumg.com/docs/Springs%26Dampers_Tech_Tip_1.pdf
http://www.optimumg.com/docs/Springs%26Dampers_Tech_Tip_2.pdf
http://www.optimumg.com/docs/Springs%26Dampers_Tech_Tip_3.pdf
http://www.optimumg.com/docs/Springs%26Dampers_Tech_Tip_4.pdf
http://www.optimumg.com/docs/Springs%26Dampers_Tech_Tip_5.pdf
http://www.optimumg.com/docs/Springs%26Dampers_Tech_Tip_6.pdf

[anyonebutme]

Consider me surprised as hell. For reference, BMW E36 rear suspension, nearly identical in configuration to ours, when in coilover is known to have a 1:1.07 MR going off memory:

http://i1323.photobucket.com/albums/u590/Cody_Nieders/9167B000-8A8C-43F5-B2F1-8B0896A408BA-3060-000001603A425BA3_zps70c51a6c.jpg

My car was twitchy and unstable as hell on 9K/7K split.......I'm just imagining 9K/9K oversteer.

[anyonebutme]

I just measured my car, all stock suspension arms, AWS deleted and links in "neutral" position, forward cam bolts in most forward position. 0 toe. stockish ride height. I got a motion ratio over 1.

Reference measurement - Damper length

16 - 23.375
15 - 22.0625
14 - 20.9375
13 - 19.8125
12 - 18.75


It's completely possible I'm tripping, so Jeremy, can you recheck your car? I got a stable spot at 1.125 MR (not squared) right in compression of my ride height.

[edit]: measured with both springs disconnected to avoid chassis warp possibly modifying results.

[J. Fast]

What is the perch gap at resting ride height? What us the gap at 1" below resting ride height. What is the gap at 1" above resting ride height?

[J. Fast]

I need the number when the tire moves 1"... Not the perch.

[anyonebutme]

10.375, 8.125

Comes out same.

[edit]: those are perch to perch, 1" below and 1" above ride height

[J. Fast]

10.375, 8.125

Comes out same.

[edit]: those are perch to perch, 1" below and 1" above ride height

1.26 motion ratio... Hrmmm. Danger Will Robins! LOL... I will check again... This is wierd.

[anyonebutme]

dangerously close to my initial measurements of my spare subframe....


Plugging in stock spring rates....

[anyonebutme]

quick rough plugging of the numbers means .98 and 1.26 motion ratios makes sense with stock spring rates and corner weights, at least to me.

[Rakuny]

Erron, are those your weights with or without you in the car? your cross weights seem really weird to me.. this is my car
http://imageshack.us/a/img832/2822/1003194w.jpg (http://imageshack.us/photo/my-images/832/1003194w.jpg/)
Without me in it..
http://imageshack.us/a/img547/2143/1003198u.jpg (http://imageshack.us/photo/my-images/547/1003198u.jpg/)
With me in it..
http://imageshack.us/a/img607/6614/1003200l.jpg (http://imageshack.us/photo/my-images/607/1003200l.jpg/)

I have been running 6.3kg front and 6.8kg rears

[2fnloud]

Marc who has scales? I need to get my car corner weighted soon.

[J. Fast]

Erron, are those your weights with or without you in the car? your cross weights seem really weird to me.. this is my car
http://imageshack.us/a/img832/2822/1003194w.jpg (http://imageshack.us/photo/my-images/832/1003194w.jpg/)
Without me in it..
http://imageshack.us/a/img547/2143/1003198u.jpg (http://imageshack.us/photo/my-images/547/1003198u.jpg/)
With me in it..
http://imageshack.us/a/img607/6614/1003200l.jpg (http://imageshack.us/photo/my-images/607/1003200l.jpg/)

I have been running 6.3kg front and 6.8kg rears


Mark,

This is the Erron's setup with driver.

http://i788.photobucket.com/albums/yy163/JFastMotorsports/Photo_052712_028_zps4f587ae5.jpg

My diagonal bias is the same as yours about 49%.

[Erron Spalsbury]

Thanks Jer! That's the image I was looking for.

[J. Fast]

Thanks Jer! That's the image I was looking for.


Your new bias should be somewhere in the 960's for the fronts and 610's in the rear (49X51) diagonals. Raceweight around 3100 w/driver.

[anyonebutme]

[edit]: nevermind, figured it out.

[Rakuny]

Mark,

This is the Erron's setup with driver.

http://i788.photobucket.com/albums/yy163/JFastMotorsports/Photo_052712_028_zps4f587ae5.jpg

My diagonal bias is the same as yours about 49%.

hmm, I guess I meant why is the RR weight almost 800 lbs?

[Rakuny]

Also just for general reference I found this picture on one of the forums a while back.
pretty much stock 2g car weights (no driver)
http://i49.tinypic.com/xangg9.jpg

[anyonebutme]

Levi's car:

http://img.photobucket.com/albums/v55/PrestoTuna/forum%20misc/IMG_20130316_192420_481_zps3483faea.jpg

http://img.photobucket.com/albums/v55/PrestoTuna/forum%20misc/IMG_20130316_192430_620_zps8ddd7a3e.jpg

Balanced as much as possible without moving anything or effecting ride heights.

[95gto]

Levi's car:

http://img.photobucket.com/albums/v55/PrestoTuna/forum%20misc/IMG_20130316_192420_481_zps3483faea.jpg

http://img.photobucket.com/albums/v55/PrestoTuna/forum%20misc/IMG_20130316_192430_620_zps8ddd7a3e.jpg


Balanced as much as possible without moving anything or effecting ride heights.

And this is with me in the car at just over 220lbs.

[mehrshadvr4]

Found something cool on the net by accident. this has so much potential and you can do it to almost any car.

http://www.youtube.com/watch?v=jMOaYrDJKwE

[IPD]

is that so you can adjust the suspension from inside the cabin with low-tech coilovers?

[Erron Spalsbury]

Hmmm, push rod suspension from an open wheel or DSR, that's not low tech, that's WAY hi-tech. :)

[anyonebutme]

Pushrod suspension is dangerously easy to screw up.

[IPD]

Hmmm, push rod suspension from an open wheel or DSR, that's not low tech, that's WAY hi-tech. :)

as opposed to magneto-ferrous fluid dampers with electronic control? yes...i'd say it's very low tech.

[Erron Spalsbury]

as opposed to magneto-ferrous fluid dampers with electronic control? yes...i'd say it's very low tech.

Touche' !

[MR2]

how much weight will converting to pushrod add to the car?

[JGreenwood238]

I ran 10k springs front and rear for awhile on my SL and liked it till the stock struts blew. I switched to Megan coilovers which are sprung more in the front. The shocks are much better than stock but in the rear I had to bump up the damping and add a 1/4" of spring preload to get the car to handle like it did with the 10k front and rear. Stiffening the rear relative to the front seems to just about eliminate understeer entirely. The car handles very neutral now. I know my car is fwd but I think the vr4 would benefit from stiffer rear springs as well.

Sent from my Galaxy Nexus using Tapatalk 2

[J. Fast]

Our chassi is begging for more rear spring guys.

This looks really really familiar ;)

http://www.momentummotorsport.co.uk/images/prodducts_lightrear4_big.jpg

[J. Fast]

Hey guys, I wanted to update this with more information on calculating the actual wheel rates.

Once the motion ratio is determined apply this formulae...

Wheel Rate = ( ( MR^2) x SpringRate ) * sine(Spring Angle)

I'm working on a video for future reference. With any luck I'll have it posted by Saturday. I'll have the wheel/shock travel measurements thru 6" of articulation and the spring angles of inclination to properly calculate this thing.

[wingnut]

http://www.momentummotorsport.co.uk/images/prodducts_lightrear4_big.jpg

Hmmmm...mitsu evo?

[Nihil]

Hey, Jeremy, you ever figure this out? Or anyone else? This was an interesting read, been subscribed, never posted until now, since it's been awhile with no updates, and I've been researching this stuff since coilovers are on my list of next buys when I have the money

[J. Fast]

I measured the motion ratio for all 3 of my vehicles. The race car, sandstone, and my street car. The motion ratio at the rear is identical for all of them. I confirmed it to be 1.00. For every one inch of wheel travel each corner articulates one inch.

These are my confirmed calculations.

REAR SUSPENSION:

1.5" rideheight = 8" perch to perch gap
2.5" rideheight = 9" perch to perch gap
3.5" rideheight = 10" perch to perch gap
4.5" rideheight = 11" perch to perch gap.

I disconnected the sway bar and removed the strut springs and fully unloaded the suspension. I then reinstalled the shocks by themselves and the wheels and measured. The above are my results. I have pictures, I will post them if I have time (hopefully this afternoon).

[J. Fast]

I determined the spring rates for the front and rear of the vehicle should be the same if you are running an oem rear wing or larger. If the front springs are heavier than the rears then the suspension is likely set up incorrectly and you're doing it wrong. Also, if you're lifting a tire on roadcoarse you have too much spring and your scrubbing speed. I spoke with Rhys Millen about his lifting a tire at pikes peak because his suspension was setup for drifting and was too stiff. His crew chief determined they scrubbed about 0.20 per corner from loss in wheel contact.

Its manageable to have the suspension setup to stiff, but you have to wait for the suspension to settle. While you're waiting you're losing time.

[J. Fast]

Here's the photodocumented real world results of the Motion Ratio for the rear end... it is a true 1:1

1/2" Ride Height

http://i788.photobucket.com/albums/yy163/JFastMotorsports/20130605_141936_zpsf40e84f7.jpg

http://i788.photobucket.com/albums/yy163/JFastMotorsports/20130605_142046_zps95f72e1f.jpg

1.5" Ride height

http://i788.photobucket.com/albums/yy163/JFastMotorsports/20130605_142245_zps11293617.jpg

http://i788.photobucket.com/albums/yy163/JFastMotorsports/20130605_142424_zps82a8d7ed.jpg

2.5" Ride Height

http://i788.photobucket.com/albums/yy163/JFastMotorsports/20130605_142529_zps1c5c77fe.jpg

http://i788.photobucket.com/albums/yy163/JFastMotorsports/20130605_142625_zps8d1c0187.jpg

3.5" Ride Height

http://i788.photobucket.com/albums/yy163/JFastMotorsports/20130605_142804_zpsd0e54989.jpg

http://i788.photobucket.com/albums/yy163/JFastMotorsports/20130605_142848_zpse863a505.jpg

[J. Fast]

According to the wind tunnel testing that was conducted by the Russians there's a hundred twenty pounds of lift on each corner in the front and approximately 150 pounds down force at each corner at the rear when Active Aero is engaged.
I'm seeing corner weighed setups with 950 lbs at the fronts and 700 lbs at the rears. When you add aerodynamics into the equation the wheel rates for all the corners are equal therefore it would appear that all the aftermarket suspension options available for VR4's are set up incorrectly unless the spring rates in the front and rear are equal. It's looking like 10k front and rear its a good starting point. If you have a GTC 300 wing or bigger add a couple hundred pounds to the rear Springs. That's just my. 02

[Nihil]

Awesome! Great solid, confirmed information! Looks like the Ksport Version RR #CMT191-RR are setup even at 14k/14k and that's the only one out of the box I could find with a proper starting point.

Having this information now, it'll be interesting to see some testing done from those who have coilovers installed, to play with different spring rate setups.


It's looking like 10k front and rear its a good starting point.

When you say good starting point, what is this a good usage starting point for? Road course? Auto cross? or?

Thanks for the research on this Jeremy!

[sergechronos]

Spring Rate


kg/mm
3
4
5
6
7
8
9
10
12
14
16
18
20
22
24
26
28


lb/in
168
225
281
337
393
450
506
564
674
787
899
1012
1124
1232
1344
1456
1568





Let's see here, assuming proper corner balancing and a speed of 70mph, Known Front Motion Ratio of 1:0.98, Rear Motion ratio of 1:0.84 @ 2" drop and MR of 1:0.86 at stock ride height. Estimated 600 lbs rake/frontal downforce and 500lb downforce in rear.

1. Stock 3/S Ride Freq of 1.60Hz corners weights of 1270lb fronts, 720lb rears
2. Stock 3/S Ride Freq of 1.75Hz w/1.25" drop, corner weights of 1270 fronts, 720lb rears
3. Modified 3/S Ride Freq of 2.05Hz w/1.5" drop, corner weights of 1000lb fronts, 650lb rears
4. Because Spec Racecar 3/S w/ Ride Freq of 2.2Hz w/2" drop, corner weights of 965lb fronts, 585 rears

Wheel Rate = ((60(Hz))/(187.8))^2 x (corner weight)

1. Wheel Rate:

FRONT ((60(1.6))/(187.8))^2 x 1270= 332lb
REAR ((60(1.87))/(187.8))^2 x 720= 257lb


2. Wheel Rate:

FRONT ((60(1.75))/(187.8))^2 x 1270= 397lb
REAR ((60(2.02))/(187.8))^2 x 720= 300lb


3. Wheel Rate:


FRONT ((60(2.05))/(187.8))^2 x 1000= 429lb
REAR ((60(2.32))/(187.8))^2 x 660= 363lb


4. Wheel Rate:


FRONT ((60(2.2))/(187.8))^2 x 965= 475lb With Aero: FRONT ((60(2.2))/(187.8))^2 x 1265= 625lb
REAR ((60(2.47))/(187.8))^2 x 585= 364lb With Aero: REAR ((60(2.47))/(187.8))^2 x 835= 519lb


Spring Rate = (Wheel Rate) / (Motion Ratio)^2

1. Spring Rate:


FRONT (332)/(.98)^2= 346lb
REAR (257)/(.86)^2= 347lb


2. Spring Rate:


FRONT (397)/(.98)^2= 413lb
REAR (300)/(.86)^2= 405lb

3. Spring Rate:


FRONT (429)/(.98)^2= 437lb
REAR (363)/(.84)^2= 514lb


4. Spring Rate:


FRONT (475)/(.98)^2= 494lb With Aero: FRONT (625)/(.98)^2= 651lb
REAR (364)/(.84)^2= 515lb With Aero: REAR (519)/(.82)^2= 735lb



According to the ref table above it's looking like beacuse racecar wants... 11K fronts and 13K rears.

I'd say GT Worx and Meullerized are about spot on with the bias.

That's enough for today.

Forgive me if I'm wrong (especially in light of doing this during a bout of insomnia), but it would seem then that this entire table would now be wrong then since we have a known rear MR of 1:1 wouldn't it? Different MR modifies at the very least the spring rate, giving very different rates than previously obtained. Possibly wheel rate as well. Quick and dirty math following #2 in the table, assuming AA as well, would give ~519 front and ~404 rear with a 1:1 rear MR. That would give spring rates of approx 9k front and around 7k rear, which we determined at the very beginning of this would be very wrong. Again, just based on following the table and plugging in updated rear MR info, and adjusting weights for AA.

If this is right (which I doubt), perhaps just edit the post to indicate that the information will need to be altered and get back to it later. Has me thinking further than without proper corner weighting, what the typical street 3/S should see would probably be around 8k all around, maybe 9k driver side front since we don't have the balance of being RHD. Hard to brainificate right now, but I think 10k is probably on the higher side for a full weight car.

Lot of variables for folks to consider though. Would be nice to get a stock (or mostly stock) car on a K&C machine, then take it back with these coil over set ups and see what the difference is. Information wouldn't be too useful for most of your hardcore racers out there, but would apply to a much larger percentage of the community.

[Erron Spalsbury]

I determined the spring rates for the front and rear of the vehicle should be the same if you are running an oem rear wing or larger. If the front springs are heavier than the rears then the suspension is likely set up incorrectly and you're doing it wrong. Also, if you're lifting a tire on roadcoarse you have too much spring and your scrubbing speed. I spoke with Rhys Millen about his lifting a tire at pikes peak because his suspension was setup for drifting and was too stiff. His crew chief determined they scrubbed about 0.20 per corner from loss in wheel contact.

Its manageable to have the suspension setup to stiff, but you have to wait for the suspension to settle. While you're waiting you're losing time.

Too little of a spring and you'll lift a tire. I think Rhys was messing with you as it's clearly the other way around.

[J. Fast]

Too little of a spring and you'll lift a tire. I think Rhys was messing with you as it's clearly the other way around.

Kinda, but not really seeing the need for 20k springs on a 3S... if springs are properly selected and we're lifting tires? That's a sway bar issue and possibly a weight transfer issue. In the event of weight transfer we can adjust the weight distribution by changing the corner weight bias. IE change the rideheight on the corners till they cancel another out. Additionally, we use sway bars and geometry adjustments to keep all the tires planted. I seriously doubt we have a roll stiffness issue that warrants 20k springs on the corners and a 1/2" of suspension travel. More sway and less spring combined with proper bump steer keeps the tires down while maintaining ideal compliance.

[Nihil]

According to the wind tunnel testing that was conducted by the Russians there's a hundred twenty pounds of lift on each corner in the front and approximately 150 pounds down force at each corner at the rear when Active Aero is engaged.
I'm seeing corner weighed setups with 950 lbs at the fronts and 700 lbs at the rears. When you add aerodynamics into the equation the wheel rates for all the corners are equal therefore it would appear that all the aftermarket suspension options available for VR4's are set up incorrectly unless the spring rates in the front and rear are equal. It's looking like 10k front and rear its a good starting point. If you have a GTC 300 wing or bigger add a couple hundred pounds to the rear Springs. That's just my. 02

Does anyone know about the other wings, including stealth? I remember reading the 1g active aero wing had the most down force of all the stock variables, curious about the stealth, with it's flow directing sail panels and stupid looking banana wing lol.

What are stock spring rates? Curious what the engineers equated as perfection. Thinking about all of this information now, it's weird to think why anyone would go lighter in the rear, with the added aero forces. At best, equal does seem to make the most sense, although, at what speeds, I don't know...but heavier rear seems logical

[B-Man]

Does anyone know about the other wings, including stealth? I remember reading the 1g active aero wing had the most down force of all the stock variables, curious about the stealth, with it's flow directing sail panels and stupid looking banana wing lol.

What are stock spring rates? Curious what the engineers equated as perfection. Thinking about all of this information now, it's weird to think why anyone would go lighter in the rear, with the added aero forces. At best, equal does seem to make the most sense, although, at what speeds, I don't know...but heavier rear seems logical

Understeer is safer for the average driver. Most car manufacturers purposely set cars up to be understeering pigs from the factory because it's safer.

[J. Fast]

I think in fairness this thread will be limited to setups capable of sustaining a lateral g or lower. Street/strip combo type vehicles or HPDE's that maybe have an occasional track visit. It's really a different animal when you have a setup that sticks so well you flex the chassis and need a suspension that's picked up and reinforced by the cage. I'm talking all four corners tied to the cage and structural rigidity work. I don't really want to get into the complexity of why dual rate springs vs. single springs vs utilizing helpers with either setup and etc... Dual adjustable strut vs. triple and four way adjustable struts and etc. What I will say is there's a light year difference between an off the shelf Megan, KSport, KW, BC, and Tein vs an AST 4100+, JRZ , Ohlin and etc.

What I think is fair to discuss is good modeling, measuring, and good principle function/operational limitations and constraints regarding what we have off the showroom floor (this is what we have... and these are the limitations to stock chassis setup whether it be caster or camber due to McStrut, valving limitations, avail grip, bump steer behavior based on adjusted ride height and suspension travel, geometry behavior and so forth).

What we need before anything is a good model built from actual measurements that account for a majority of the elements such as suspension travel, aero, tire selection, environment, road surface and etc. Once the model is built and realized on the vehicle we employ data acquisition and test test and test to dial it in.

I think 99% of owners should know that for many many years the spring rates and valving for what's avail can be improved. Additionally there's good setups avail that bolt on with Adapters.

I might circle back and correct my spring rate and wheel rates based on my recent findings from actual measurements, but not atm... Im wrapped up in a few things and don't have time.

[J. Fast]

Understeer is safer for the average driver. Most car manufacturers purposely set cars up to be understeering pigs from the factory because it's safer.

This is correct. With the suspension biased to understeer we're pointed to the outside shoulder or guardrail which usually has a buffer built in. If our suspensions were oversteer*biased... if the rear end broke lose you would be pointed at oncoming traffic on turn exit. I would suspect there's a NHTSB understeer requirement intentionally in place which likely reduces head on collisions on two way roads with hair-pin turns.

If you can drive the understeer condition can be removed and improved :)

[sergechronos]

Even if you don't go back and edit the table or anything, people should take the time to read this whole thread as it is completely in conflict with most current available coil overs that folks run. Not sure how interchangeable the springs are on most of those models to change the performance. The principle thing to take away from this for folks would seem to be that the front and rear should at least at the same rate or close to it, potentially slightly stronger rates for the rear (without AA or combat wing) and drive front (due to weight distribution)

[J. Fast]

Also, the dampeners should be valved matched to the setup.

[anyonebutme]

There was a study done that showed that for a typical driver, understeer is actually more dangerous than a car with consistent oversteer. I'll be damned if I can't find it, but the way it was explained to be makes total sense. The way most AWD cars handle is actually the most dangerous, with understeer transitioning to snap oversteer under braking.

Keep in mind, that 150 lbs of downforce was at like 150/170 MPH? For the typical track day guy....setting your suspension up for that isn't going to be helpful in 99% of corners at tracks in America. Or ANY autocross.

[Nihil]

There was a study done that showed that for a typical driver, understeer is actually more dangerous than a car with consistent oversteer. I'll be damned if I can't find it, but the way it was explained to be makes total sense. The way most AWD cars handle is actually the most dangerous, with understeer transitioning to snap oversteer under braking.

Keep in mind, that 150 lbs of downforce was at like 150/170 MPH? For the typical track day guy....setting your suspension up for that isn't going to be helpful in 99% of corners at tracks in America. Or ANY autocross.

That's kinda what I was thinking about the understeer thing...understeer and you end up across the way in oncoming traffic, real quick...regardless, though, it'd sure be nice to have a car that oversteers in a nice controllable manner.

Looks like an even biased spring rate between front and rear is what is desired, I wouldn't think the wing comes into play until fairly high speeds, at which, I don't see utilizing through cornering, where our problem is.

That aside, as mentioned, looks like the ksport RR series are the only aftermarket, off the shelf coilover that is setup correctly, which means it's valving should match the spring rates as well...I believe all others, you can request different spring rates, but does that mean the valving is corrected for the requested rates? Doubt it...I wonder what 14k would be like for a DD though and I wonder what it'd be like to get whatever stock fronts are, then match the rears to them to balance it out.

[wingnut]

...in for good reading material, even if nothing comes of it :D

[vr4tune]

This is correct. With the suspension biased to understeer we're pointed to the outside shoulder or guardrail which usually has a buffer built in. If our suspensions were oversteer*biased... if the rear end broke lose you would be pointed at oncoming traffic on turn exit. I would suspect there's a NHTSB understeer requirement intentionally in place which likely reduces head on collisions on two way roads with hair-pin turns.

If you can drive the understeer condition can be removed and improved :)


That's kinda what I was thinking about the understeer thing...understeer and you end up across the way in oncoming traffic, real quick...regardless, though, it'd sure be nice to have a car that oversteers in a nice controllable manner.

Looks like an even biased spring rate between front and rear is what is desired, I wouldn't think the wing comes into play until fairly high speeds, at which, I don't see utilizing through cornering, where our problem is.

That aside, as mentioned, looks like the ksport RR series are the only aftermarket, off the shelf coilover that is setup correctly, which means it's valving should match the spring rates as well...I believe all others, you can request different spring rates, but does that mean the valving is corrected for the requested rates? Doubt it...I wonder what 14k would be like for a DD though and I wonder what it'd be like to get whatever stock fronts are, then match the rears to them to balance it out.

maybe I'm not following correctly but wouldn't that depend on what direction you are turning. Example turning left would be safer to have understeer, while turning right would be safer to oversteer, when considering on comming traffic. (Assuming we're driving on the right side of the road. [driving on the left side of the road would be the opposite.])

maybe we're talking about NASCAR and I didn't catch the hint.

[CoopKill]

http://i196.photobucket.com/albums/aa123/teeroyfte/angrygnome.jpg

[Nihil]

maybe I'm not following correctly but wouldn't that depend on what direction you are turning. Example turning left would be safer to have understeer, while turning right would be safer to oversteer, when considering on comming traffic. (Assuming we're driving on the right side of the road. [driving on the left side of the road would be the opposite.])

maybe we're talking about NASCAR and I didn't catch the hint.

True...I suppose, rather than talk about this theory, we end with this...fuck understeer! Problem seems to have been found? We need to solve it once and for all? haha


http://i196.photobucket.com/albums/aa123/teeroyfte/angrygnome.jpg

W.T.F. Bill...get that Gnome outta here! lol I've never seen David so pissed before!?

[J. Fast]

maybe I'm not following correctly but wouldn't that depend on what direction you are turning. Example turning left would be safer to have understeer, while turning right would be safer to oversteer, when considering on comming traffic. (Assuming we're driving on the right side of the road. [driving on the left side of the road would be the opposite.])

maybe we're talking about NASCAR and I didn't catch the hint.

Lol wiseguy. Understeer you drive thru the front tires and see where you are going off the road. A buffer zone is where you farm to on a racetrack which you have no clues about. Oversteer and lol now you're facing the car behind you becausetheassendslidesaroundthetires and promotes a spin. SIGH...

[anyonebutme]

I'll try and explain:

You enter a corner and turn the wheel, car turns. Turn the wheel more and car turns more. Turn the wheel more and with understeer the car turns no harder. Turn the wheel more and car turns LESS. The solution is to turn the wheel back some, which is an unnatural thing to do and requires training to deal with.

You enter a corner and turn the wheel, car turns. Turn the wheel more and car turns more. Turn the wheel more and with oversteer the car turns more. Turn the wheel more and car "turns"/rotates MORE. When the car rotates too much it is a natural movement to turn the wheel less.

Benign oversteer is safer than understeer.

[CoopKill]

I want Neutral with a Over steer bias, is that too much to ask? lol

[vr4tune]

Lol wiseguy. Understeer you drive thru the front tires and see where you are going off the road. A buffer zone is where you farm to on a racetrack which you have no clues about. Oversteer and lol now you're facing the car behind you becausetheassendslidesaroundthetires and promotes a spin. SIGH...


No I understand oversteer and understeer just fine. You never said in you first post that your HEAD ON COLLISION was from the car BEHIND you (meaning you spun 180* around). YOU MENTIOND "ON COMMING TRAFFIC" IMPLYING STREET DRIVING NOT RACING AT A TRACK. I thought you were saying that oversteer would cause you to go into the left lane in to oncoming traffic. Don't get arrogant just yet as that was your down fall on 3si with your 19t is so great thread, and you posting up a fake dyno graph Drmbldr.

Must Read!!! 19T's are the best turbo for a 3.0L or 3.1L 3000GT - 3000GT/Stealth International Message Center (http://www.3si.org/forum/f35/must-read-19ts-best-turbo-3-0l-3-1l-3000gt-462606/)

[CoopKill]

This is correct. With the suspension biased to understeer we're pointed to the outside shoulder or guardrail which usually has a buffer built in. If our suspensions were oversteer*biased... if the rear end broke lose you would be pointed at oncoming traffic on turn exit. I would suspect there's a NHTSB understeer requirement intentionally in place which likely reduces head on collisions on two way roads with hair-pin turns.

If you can drive the understeer condition can be removed and improved :)I believe that Brett was pointing out the failed theory behind the bolded statements, and you basically called him out as an idiot.

[Erron Spalsbury]

Guys, understeer (for the unskilled driver) is always safer, period. Going too fast into a corner and the car scrubs speed and goes straight with ZERO additional skill or input. Oversteer or more importantly snap oversteer or even sometimes called doing the 10 knuckle shuffle is about the most scary thing for a new driver or someone that has never had to deal with it. I used to be a driving instructor for the HPDE with SCCA. I promise you, understeer had much better results for the newbie.
Just for fun, here's a neat example.

http://www.youtube.com/watch?v=YtmuVLjvUcA

[J. Fast]

Guys, understeer (for the unskilled driver) is always safer, period. Going too fast into a corner and the car scrubs speed and goes straight with ZERO additional skill or input. Oversteer or more importantly snap oversteer or even sometimes called doing the 10 knuckle shuffle is about the most scary thing for a new driver or someone that has never had to deal with it. I used to be a driving instructor for the HPDE with SCCA. I promise you, understeer had much better results for the newbie.
Just for fun, here's a neat example.
]

LOL, vr4tune doesn't care Erron. As long as his opinion is opposite of mine and he can talk s*** he will. Its all good... nothing to be up in arms about. Karma's just free flowing out there. It shows up and strips cars and blows engines.

I'll be at the track this weekend if you want to go Erron. I think I'm going to go play and turn some laps too. I want to test out my new Meullerized suspension, some new tires, and a set of Hawk Performance track pads on the AP Racing brakes on a recc from Bill @ Mac.

[Erron Spalsbury]

Hey, that's kinda on the down low from what I understand, might want to edit that bro.

I'm taking Thursday and Friday off, we are on track Friday at noon for our test session. I was with Jake yesterday at IDRC Bandimere and he'll be there as well. I think he's just bringing one of the Evo's though, not the race car. Hal is bringing his car as well.

[sergechronos]

Guys, understeer (for the unskilled driver) is always safer, period. Going too fast into a corner and the car scrubs speed and goes straight with ZERO additional skill or input. Oversteer or more importantly snap oversteer or even sometimes called doing the 10 knuckle shuffle is about the most scary thing for a new driver or someone that has never had to deal with it. I used to be a driving instructor for the HPDE with SCCA. I promise you, understeer had much better results for the newbie.
Just for fun, here's a neat example.

http://www.youtube.com/watch?v=YtmuVLjvUcA

Of course understeer is the lesser of two evils in this case, however, I would venture most of the folks here (and the folks willing to wade through all these pages) are probably of the mindset that they can handle a neutral or slightly oversteer biased vehicle. I absolutely agree that snap oversteer is absolutely terrifying the first couple times you encounter it pushing a car.

That said, even with "optimized" coil overs, I went venture that equal rate springs on the car to get it to neutral would push the car to a slight oversteer bias with a stronger rear sway bar (given how small the factory rear is anyhow), or of course people could just opt for some slightly stiffer rear springs.

[B-Man]

Of course understeer is the lesser of two evils in this case, however, I would venture most of the folks here (and the folks willing to wade through all these pages) are probably of the mindset that they can handle a neutral or slightly oversteer biased vehicle. I absolutely agree that snap oversteer is absolutely terrifying the first couple times you encounter it pushing a car.

That said, even with "optimized" coil overs, I went venture that equal rate springs on the car to get it to neutral would push the car to a slight oversteer bias with a stronger rear sway bar (given how small the factory rear is anyhow), or of course people could just opt for some slightly stiffer rear springs.

We weren't talking about the 'mindset' of the people reading this thread and understeer. We were talking about why the car is set up from the factory the way it is.

[sergechronos]

I thought Erron was referring to Bill's wanting neutral with an oversteer bias, didn't realize we were still hung up on why cars come with understeer.

[Erron Spalsbury]

M3's come with understeer apparently. This video made me go, EEEEK!!

M3 Cliff Dive raw footage - YouTube (http://www.youtube.com/watch?v=BkasHdSb1nQ&feature=youtu.be)

[anyonebutme]

You see what I'm talking about how novice drivers turn the wheel more when understeering and causing the situation to be worse? Watch again.


That car totally could have made that corner at that speed.

[Erron Spalsbury]

Yep, which will scrub off speed typically slowing the moment of impact. In this case, he just went off a cliff.

[sergechronos]

Yep, which will scrub off speed typically slowing the moment of impact. In this case, he just went off a cliff.

Hahaha I know it's wrong to laugh at it, but I just picture you saying "Just went off a cliff" like it's some casual ordeal.

And while he did turn the wheel more and make it worse, what do you think happens with oversteer? Realistically he spins himself out and goes flying off the cliff at full speed. Of course, could be a variety of other factors at play there. Worn tires up front, or he may have lowered it and changed the handling dynamics, or upgraded a sway bar or similar to have changed it, no telling if it actually understeered from the factory or not. I digress though, I think that the understeer taking speed off is probably the only reason why he more of just rolled off the edge instead of flying straight off of it.

[Nihil]

I think everyone's made their damn points, now lets start experimenting with spring rate setups god damn it! lol We need real world results now that we have the problem sorted out!

[sergechronos]

Well, everyone will have to experiment on their own to find their happy place since everybody drives differently and I don't know that anyone is about to put their car on some kind of kinematic and chassis dyno.

I think my plan then is probably Apexi S1s with SCE adapters, then I can just buy a set of springs for anywhere from 50-80 bucks to tinker with it.

[Nihil]

Well, everyone will have to experiment on their own to find their happy place since everybody drives differently and I don't know that anyone is about to put their car on some kind of kinematic and chassis dyno.

I think my plan then is probably Apexi S1s with SCE adapters, then I can just buy a set of springs for anywhere from 50-80 bucks to tinker with it.

Yeah, I wanna hear real world results so I can figure out what where I wanna go with my setup when I get to it, meaning, if a 50/50 split works best or a 40/60 works best, I can always scale back from what Erron and J are runnin. Basically, just results if the theory is indeed correct.

Out of curiosity, why have you chosen to go with the ApexI setup over others? All coilovers are able to run different springs. Just wondering.

From everything I've looked at, Megan is the only one to actually have the brake line mounts attatched, which is a bonus, and the Ksports I posted previously, are the only ones with a 50/50 spring rate, which, I'd assume, would mean they'd have the correct valving. So, my top two choices in my opinion, at this time, would be the megans for correct fitment, or the Ksports for proper valving and spring rate. What's everyones thoughts on those assumptions?

[Erron Spalsbury]

I'm on track in a few days at High Plains Raceway testing the 1300 fronts and 1100 rears. I'll let you know my results.

[sergechronos]

Yeah, I wanna hear real world results so I can figure out what where I wanna go with my setup when I get to it, meaning, if a 50/50 split works best or a 40/60 works best, I can always scale back from what Erron and J are runnin. Basically, just results if the theory is indeed correct.

Out of curiosity, why have you chosen to go with the ApexI setup over others? All coilovers are able to run different springs. Just wondering.

From everything I've looked at, Megan is the only one to actually have the brake line mounts attatched, which is a bonus, and the Ksports I posted previously, are the only ones with a 50/50 spring rate, which, I'd assume, would mean they'd have the correct valving. So, my top two choices in my opinion, at this time, would be the megans for correct fitment, or the Ksports for proper valving and spring rate. What's everyones thoughts on those assumptions?

The S1s, from talking to a few folks who have them (Turbosincebirth has a set,) ride very comfortably on the street while still delivering markedly improved handling. Additionally, they come with 8k front 6k rear. I don't think stretching the rear out to 7.5k or so will be drastic enough to require having the valving redone. I wouldn't assume that valving is correct for any of the "cheaper" coil over kits.

As an addendum: I'm not after the bleeding edge of performance as my vehicle is still my daily driver. I want something with as close to a neutral bias and improved response as I can get while still maintaining the purpose of a GT car.

[Nihil]

I'm on track in a few days at High Plains Raceway testing the 1300 fronts and 1100 rears. I'll let you know my results.

That's still backwards from J's findings though, right?


The S1s, from talking to a few folks who have them (Turbosincebirth has a set,) ride very comfortably on the street while still delivering markedly improved handling. Additionally, they come with 8k front 6k rear. I don't think stretching the rear out to 7.5k or so will be drastic enough to require having the valving redone. I wouldn't assume that valving is correct for any of the "cheaper" coil over kits.

As an addendum: I'm not after the bleeding edge of performance as my vehicle is still my daily driver. I want something with as close to a neutral bias and improved response as I can get while still maintaining the purpose of a GT car.

I wouldn't think the valving is anything special, though still matched to whatever set of springs they accompany with the setup. From what I've read, people have different thoughts on every single coilover out there, I think some people like the stiffness and others don't so opinions vary, greatly.

I get a lot of understeer just in DD so I'm looking to eliminate as much, if not all, as possible...so I'm really into this finding, can't wait to see results, as this will determine what I end up with, as far as coilovers and spring rates.

[Erron Spalsbury]

That's still backwards from J's findings though, right?


In my opinion, no.

[J. Fast]

Nothing wrong with Erron's setup. Its big spring, little bar. You don't really get a lot of suspension travel with springs like that. It will take 4000 pounds to compress the setup a little over an inch. He's running a tire that can hold the weight. The only thing up in the air is wether or not the chassis will flex if he gets the lateral G's up. It's really difficult to keep an inside tire planted on a McStrut with a spring rate like that because of the caster and camber built into that type of design. If it were double wishbone four wheel independent?

Test test test that's the only way to know. I'm set up to hit the track this weekend and on the 23rd. Lol, I have 24 Springs to test and I still have to evaluate the motion ratio for the fronts. I haven't fully disassembled the front end and measured it yet, but I'm working on it.

[sergechronos]

That's still backwards from J's findings though, right?



I wouldn't think the valving is anything special, though still matched to whatever set of springs they accompany with the setup. From what I've read, people have different thoughts on every single coilover out there, I think some people like the stiffness and others don't so opinions vary, greatly.

I get a lot of understeer just in DD so I'm looking to eliminate as much, if not all, as possible...so I'm really into this finding, can't wait to see results, as this will determine what I end up with, as far as coilovers and spring rates.

There's a lot of variables that can effect your handling and a lot of things you can do to change it. Spring rates and stiffness will obviously have a huge impact on it, but a stronger rear sway bar will go a long ways towards helping reduce understeer. Again, these are "ideal" rates, but everybody is going to have different preferences on it. That's the thing about theory vs practice. What works in theory, doesn't always work in practice. And sometimes what works in practice shouldn't work in theory.

Erron's car, if I'm not mistaken, is basically completely stripped out and reinforced. That alone will drastically change the way that his car handles compared to a full weight street car, and you're looking to achieve totally different goals from it.

[Erron Spalsbury]

Nothing wrong with Erron's setup. Its big spring, little bar. You don't really get a lot of suspension travel with springs like that. It will take 4000 pounds to compress the setup a little over an inch. He's running a tire that can hold the weight. The only thing up in the air is wether or not the chassis will flex if he gets the lateral G's up..

That much compression would only be applicable going straight and under DF loads. Otherwise, it's what the springs are. In this case the fronts at 1300lbs/in it would take 1300 pounds to compress it one inch as these are linear springs and not progressive. Initial testing on the Hoosiers on a non track surface (read:road) has shown significantly higher G loads but the real data will come Friday.

[Nihil]

This is all interesting and cool findings/discussion none the less.

I know everyone is going to have/want different needs/requirements. But it still seems J's findings are leading toward a 50/50 split, which is a huge setup difference compared to the average, for our platform.

Erron, you mention linear springs vs progressives...I've always wondering this. In motocross/supercross progressive springs are generally garbage and swapped out for a straight weight spring and revalving which improves the factory suspension by miles. Thoughts on this? Progressives in the opinions of others and my own, are more of a comfort thing, smooth comfortable ride and as you ride harder, stiffer to take the abuse, but that's more of a paper theory than an actual reality...in the dirtbike world anyway.

[Erron Spalsbury]

This is all interesting and cool findings/discussion none the less.

I know everyone is going to have/want different needs/requirements. But it still seems J's findings are leading toward a 50/50 split, which is a huge setup difference compared to the average, for our platform.

Erron, you mention linear springs vs progressives...I've always wondering this. In motocross/supercross progressive springs are generally garbage and swapped out for a straight weight spring and revalving which improves the factory suspension by miles. Thoughts on this? Progressives in the opinions of others and my own, are more of a comfort thing, smooth comfortable ride and as you ride harder, stiffer to take the abuse, but that's more of a paper theory than an actual reality...in the dirtbike world anyway.

Exactly correct. The nice thing about progressive is they kind of do the best of both worlds. Mild suspension travel offers a nice comfy ride while tossing it in deep offers a stiffer spring rate. For a track only car I personally don't like them as the delay in weight transfer to load up spring takes additional time.

[J. Fast]

If you're looking for the best of both worlds you run dual rate springs. That's what I have selected to upgrade to since my JRZ suspension is tunable in droop and compression . I'm going to compensate a little weight for droop and small road imperfections on a 200lb tender spring and then on the other side of the isolator I'll be running somewhere in the range of a 600-pound mainspring. If the mainspring needs fine tuning I'll add helper springs. Effectively what the setup is designed for is a nice soft stock like ride for the first to say half inch to 1 inch of suspension travel and then when I hit the crossover point and my tender bottoms out I take on the rate of the larger spring and the combined crossover. It's not really a progressive spring type setup. Its a setup design for curvy mountain like driving with hairpin turns and camber banked turns. The very little bit of droop that I preload in will help keep the inside tire down on the ground without having to put in 1200 pound Springs. Anyone who's ever nav'd in a car with suspension that stiff knows that its rough on the butt, will bust up your back, and chatter your teeth from ride harshness. That is a 100 percent road course only spring rate, lol. Both types of setups achieve the same thing we're after... tire contact.

1 drastically big difference between the two is that a softer spring rate with droop built in allows you to accelerate from the apex of a corner wherin with big spring you have to wait for the car to settle on the tire before you can accelerate. There is a workaround for it... It's called electronic YAW, but we don't have the luxury of electronicly adjusting grip at each corner independently. The setup I'm after is more of a universal set up verses road course only.

[Erron Spalsbury]

1 drastically big difference between the two is that a softer spring rate with droop built in allows you to accelerate from the apex of a corner wherin with big spring you have to wait for the car to settle on the tire before you can accelerate. There is a workaround for it... It's called electronic YAW, but we don't have the luxury of electronicly adjusting grip at each corner independently. The setup I'm after is more of a universal set up verses road course only.

What do you mean by "settle on a tire"? (did we switch to a Rally discussion when I wasn't paying attention?) That's one big reason to go with a stiffer spring, weight transition is so much faster. This guy, had too soft of springs....LOL

http://imageshack.us/a/img17/5660/chumpcar2010pueblo70the.jpg

[J. Fast]

Hey, I remember that. Kinda yes, but really,no. That right there is a perfect example of driving beyond the limits of our suspension. We were well beyond the valving blow off point and had a terrible knee for the application ( we couldn't afford better ) consequently. we were slamming the bumpstops. Even if we added more spring we were well beyond the valving capability of our dampeners... so far beyond our valving it was impossible to keep the shock off the bump stops. More spring would have helped, but really but we need was a suspension optimized for our setup. Unfortunately, because of the rules, we were quite limited to what we could put on without having to take on penalty laps or get kicked off the track like the Miata team did, lol.

If you believe multiple rate spring setups are solely intended for rally you're mistaken. They are segways to adjustable valving points in dampeners with available adjustments. For example, JRZ triple adjustable dampener can be tuned for low, medium, and high in compression and extension. It's possible to dampen for each spring stack between the isolator so you can valve for 200lb spring , 400lb spring, and a 600-pound spring and the ride frequency associated with each stack. The reason why we don't see them more? Well, they're bloody expensive to build, but most importantly we're often limited by the overall suspension travel and how much room we have to compartmentalize multiple springs.

[anyonebutme]

I thought this was appropriate to stick here:

http://i.imgur.com/XzPsd.gif

[J. Fast]

If anyone out there is wondering wtf I'm talking about... Take a look at this:

Design your own Dual Spring-Rate Coilovers - Page 2 - Rennlist Discussion Forums (http://forums.rennlist.com/rennforums/944-turbo-and-turbo-s-forum/492186-design-your-own-dual-spring-rate-coilovers-2.html)

http://forums.rennlist.com/upload/img_2469.jpg

[J. Fast]

Lol, I like to separate the static from the noise. Gotta go work on my car get ready for the track on these :).

http://www.amsperformance.com/cart/JRZ-Mitsubishi-Lancer-Evolution-Evo-VII-VIII-IX-3-Way-Adjustable-Suspension-Kit.html

[Nihil]

In the dirt bike world, your valving is what is progressive, that's what does all your dampening, then you match a spring rate to the weight of the rider and if they surpass that, then it goes beyond their weight and into their aggressiveness as well. Having said this, when you team up a progressive spring with the valving, you get a spring that is initially soft, that progressively gets more stiff, along with the valving that does the same, which in turn, gives you a very mushy wallowing feeling along with a harshness, since the progressive spring sags into/through the softer initial valving, you end up riding on the stiffer stroke of the valving, which creates a harsh feel and over rapid rough terrain you're riding on the soft part, which is too soft because the spring is progressive, which gives you the wallowing feeling because you're just blowing through the initial stroke.

I'd think a straight rate would be best, just go with a lighter spring, rather than helper springs. In comparison, a dirt bike, going over "whoops" or rapid terrain changes, would be similar to a winding road creating body roll.

I know, two different worlds, but I'd assume the valving in car suspension is still a progressive valving, no? So in my mind, still very similar. What are the stock spring rates on our car?

I'm almost thinking, a straight rate spring with a 25-30% increase on the front, and matching the rears to that, would be a nice upgraded start? (this obviously wouldn't be the case for someone like Erron who strictly races his car, the thought is more for the person wanting an aggressive DD'er with some track use)

I dunno, I've often wondered these things and this seems to be a nice discussion thread for it so I'm just throwin my ideas/thoughts out there, let me know if I get carried away

[Erron Spalsbury]

That right there is a perfect example of driving beyond the limits of our suspension. We were well beyond the valving blow off point and had a terrible knee for the application ( we couldn't afford better ) consequently. we were slamming the bumpstops. Even if we added more spring we were well beyond the valving capability of our dampeners... so far beyond our valving it was impossible to keep the shock off the bump stops. More spring would have helped, but really but we need was a suspension optimized for our setup. Unfortunately, because of the rules, we were quite limited to what we could put on without having to take on penalty laps or get kicked off the track like the Miata team did, lol.

That Miata sucked! LOL (he kicked our ass) We weren't beyond the dampening, we were beyond the spring rate. (holy hell, WAY beyond, LOL!) The dampeners are still good. The springs were so soft, we (well, you actually) cut them so we be on the bump stops. Effectively creating a car with a billion lbs/in spring rate. All 6 drivers dropped over 5 seconds per lap the 2nd day, remember? Man, that was a fun weekend!

http://imageshack.us/a/img17/985/jercuttin.jpg



If you believe multiple rate spring setups are solely intended for rally you're mistaken. .

I never said that buddy, I asked in reference to the "tire settling" comment. I knew exactly what you were talking about, Paul had the dual spring setup on his 2G with the Penske's back at Nats in '05. The lower spring rate spring has to compress before the larger spring does.

Hey, you coming to HPR on Friday? Jake, Hal, and myself will be there. Whoot!

[Erron Spalsbury]

Ok, the track testing wen't pretty well. For those of you that don't have me on Facebook I'll cross post some of the pics from Friday.
Headed out at about 10am, car loaded, springs installed are the 1300 lb/in front and 1100 lb/in in the back. Front camber dialed back a bit, -2 and the back I left set at -3.5.

http://imageshack.us/a/img593/4338/n7cd.jpg

Got to the track and it was a nice day, mild breeze and about 90 degrees F. (notice my buddies 850 HP Eclipse behind me) He came out to play as well. LOL

http://imageshack.us/a/img577/4494/q2ld.jpg
http://imageshack.us/a/img854/207/iiz.jpg

After a nice giant hot dog from the concession stand and a lot more Pepsi than I should have drank we took to the track.

http://imageshack.us/a/img850/9499/bxu.jpg
http://imageshack.us/a/img507/8614/8r8l.jpg
http://imageshack.us/a/img24/7057/ljnq.jpg

I have some nice side car video from the GoPro but have yet to edit it down from the long weekend, that will be posted here once complete.

http://imageshack.us/a/img515/8357/l0s.jpg

First initial thoughts of massive increase in spring rate is HOLY CRAP! The car was so stable at speed. The turn in is quick and snappy and it offers a feeling from the tires that I've never had. Truly, a feedback from the car that I've never experienced. I'd hate to say it made a better driver but certainly a more aware driver. The lifting of the 4th wheel during high G loads is entirely gone now. I was told by my buddy Jake who was there spotting for me said the car looked much more controlled and level through the turns. I'd have to believe him as I felt the same way while driving. The one thing I should not have done was reduce the camber in the front wheels. I had it setup fairly well on the old springs but thought a reduction would be beneficial due to some previous inner tire wear. I should have left it, or possibly even dialed more in. Something I didn't think about was with the old springs the compression of the suspension would dial in more camber. With the additional spring rate and not as much compression I experienced some outer tire wear. I knew these slicks were on their 3rd day and didn't have much left but at about lap 25 the traction just seem to go "off" on hard right handers. Coming into the pits for a quick visual turned out to be the day ender.

http://imageshack.us/a/img195/4866/lgjr.jpg

I could have swapped it to the back and headed back out but considering I was hitting a new personal best on the front straight (184mph) I figured that would be a really bad idea to push my luck.
All in all a very successful day of testing and I'm extremely happy with these spring rates. For me it really did define the term, "the car feels like it's on rails".

[Erron Spalsbury]

A little light reading this morning and came across this.
Nerd's Eye View: Rowe Racing SLS AMG (http://www.motoiq.com/magazine_articles/id/3093/pageid/6306/nerds-eye-view-rowe-racing-mercedes-benz-sls-amg-gt3.aspx)
Third pic down they show the front suspension so I thought I'd like to see what some of the big boys run spring rate wise and low and behold, the pi shows the part number of the KW spring!
60110161
Which I found in the KW catalog, page 35.
http://www.kw-suspensions.eu/pdf/kw_racing_catalog.pdf

A quick conversion shows it to be 1541 lb/in on the fronts. I can't quite see the part number on the back one but I did notice they do run the duals on the back only. My guess would be for softer compression for when the wing comes into play or possibly to run a higher rake on the car at slower speeds. Neat stuff!

[FeaRpb]

I really love that hood.

[Unlogic]

Awesome pics!

Also like the hood, may I ask where you got it from?

[HLxDrummer]

184MPH!? That is fast..

Also, what is the thing sticking out of your hood?

[anyonebutme]

184MPH!? That is fast..

Also, what is the thing sticking out of your hood?

Thats the tow hook

[Erron Spalsbury]

184MPH!? That is fast..

Also, what is the thing sticking out of your hood?

To be fair, it's a loooong straight. I was just able to carry more speed through T3 which lead to the faster straight time.
5566

Yes, that's the tow hook. The kind that poke out of the front of the car is pretty much a spear should you T-bone someone. There's even talks of someday banning them. I personally didn't want to ever spear someone I went that route instead.

[Erron Spalsbury]

The hood came from Chaser Aerodynamics from about 3 year ago? Something like that...

[Unlogic]

The hood came from Chaser Aerodynamics from about 3 year ago? Something like that...

Thanks for information, I have to get a quote from them.

Have you had to reinforce the hood in any way in order for it to stay in one piece at 184 mph

I've seen a few stories of CF/fiberglass hoods not being stable at high speed.

[Erron Spalsbury]

I haven't. I also don't use the stock latch but dual OMP hood pins.

[J. Fast]

Yo E, what did you collect for tire data? What were your inside and outside temps on the corners? Dam you pushed that tire like mad. Haha, you totally killed it! I was hoping to see you and Hal go at it on the straightway. Good times man! Looks like you only have a few lil bugs left. You coming back out on Sunday?

[Erron Spalsbury]

16 degrees higher on the outside edge with the point and shoot IR. Not really the correct way to measure temp but I didn't have access to a probe. They didn't really go over temp, I just didn't have enough camber dialed in. No bluing on the tire so that's good. I think these tires were just about done anyway. I just pressed too hard down in Danny's Lesson to feel the load out on the heavy side of the car and lap after lap took it's toll. I'll dial in more camber and have at it again. I thought about running the cam bolts but I think I'll just hoggle out the pillow ball mount and tilt the whole enchilada. I think I'll even drop the car another inch or so as I never even came close to hitting the fender with the tire.

[J. Fast]

Want to see something crazy familiar?

http://i788.photobucket.com/albums/yy163/JFastMotorsports/Mobile%20Uploads/20130617_213513_zps38a875d0.jpg

The pic above is from a 14k front and a 10k rear. The alignment is good. I put in a bump steer to correct the shouldering . Look how bad I was pushing the tire. There's a ton of understeer bias. . I changed the rear spring rate to match the front so 14k front and rears. I shifted the bias to neutral and stopped pushing the tire. You can see it in the tire wear. I also even'd out the tire temp across the tire. I changed the tire wear issue in the suspension alone. Here's a pic of the same type of tire on the same corner with a 14k front and rear with a dual 200lb helper 1" from bind.

http://i788.photobucket.com/albums/yy163/JFastMotorsports/Mobile%20Uploads/20130617_213455-1_zpsaf9f0769.jpg

[Erron Spalsbury]

Very cool! Well, not the tire wear, but you know what I mean. LOL

Next time out I'm taking a paint pen, doing one lap with horizontal lines across the tire so I can see more of which portion of the tire I'm using.

[Nihil]

14k front and rear with a dual 200lb helper 1" from bind.

What's the ride like as a DD?

So, all thoughts/theories/hunch were correct then? We benefit more from a 50/50 biased spring rate?

*side note* you guys are awesome, wish I could race! Love the pics!

[mehrshadvr4]

Ok, the track testing wen't pretty well. For those of you that don't have me on Facebook I'll cross post some of the pics from Friday.
Headed out at about 10am, car loaded, springs installed are the 1300 lb/in front and 1100 lb/in in the back. Front camber dialed back a bit, -2 and the back I left set at -3.5.

http://imageshack.us/a/img593/4338/n7cd.jpg

Got to the track and it was a nice day, mild breeze and about 90 degrees F. (notice my buddies 850 HP Eclipse behind me) He came out to play as well. LOL

http://imageshack.us/a/img577/4494/q2ld.jpg
http://imageshack.us/a/img854/207/iiz.jpg

After a nice giant hot dog from the concession stand and a lot more Pepsi than I should have drank we took to the track.

http://imageshack.us/a/img850/9499/bxu.jpg
http://imageshack.us/a/img507/8614/8r8l.jpg
http://imageshack.us/a/img24/7057/ljnq.jpg

I have some nice side car video from the GoPro but have yet to edit it down from the long weekend, that will be posted here once complete.

http://imageshack.us/a/img515/8357/l0s.jpg

First initial thoughts of massive increase in spring rate is HOLY CRAP! The car was so stable at speed. The turn in is quick and snappy and it offers a feeling from the tires that I've never had. Truly, a feedback from the car that I've never experienced. I'd hate to say it made a better driver but certainly a more aware driver. The lifting of the 4th wheel during high G loads is entirely gone now. I was told by my buddy Jake who was there spotting for me said the car looked much more controlled and level through the turns. I'd have to believe him as I felt the same way while driving. The one thing I should not have done was reduce the camber in the front wheels. I had it setup fairly well on the old springs but thought a reduction would be beneficial due to some previous inner tire wear. I should have left it, or possibly even dialed more in. Something I didn't think about was with the old springs the compression of the suspension would dial in more camber. With the additional spring rate and not as much compression I experienced some outer tire wear. I knew these slicks were on their 3rd day and didn't have much left but at about lap 25 the traction just seem to go "off" on hard right handers. Coming into the pits for a quick visual turned out to be the day ender.

http://imageshack.us/a/img195/4866/lgjr.jpg

I could have swapped it to the back and headed back out but considering I was hitting a new personal best on the front straight (184mph) I figured that would be a really bad idea to push my luck.
All in all a very successful day of testing and I'm extremely happy with these spring rates. For me it really did define the term, "the car feels like it's on rails".
184 is fast. So is your over heating issue gone? Did you try that coolant system bleeder that I showed you before?

[Erron Spalsbury]

So, all thoughts/theories/hunch were correct then? We benefit more from a 50/50 biased spring rate?



Not in my case. The majority of the weight is still in the front of the car. Even with the big wing and diffuser there's little chance I'm pulling another 700 lbs of downforce from both which would make the car more of a 50/50 weight split. What I need to do is put zip ties on the shocks and find a long straight road. Take the car up to speed and see how much downforce is put on the rear. From the springrate (1100 in my case) I can extrapolate how much the wing and diffuser generate. Keep in mind that any posted downforce is typically rated with the car it was tested on as very different results come from different cars.

[Erron Spalsbury]

Oh, and no the overheating is still there unfortunately. I know what it is, I've just been reluctant to actually do it.

[J. Fast]

So this tire thing, E... check this out man, this really awesome guy Steve Sulatycki put this together for our McStrut behavior. When we lower our suspension we lower the roll center but we actually spread the instant centers which promotes more roll and induces rear wheel lift and exacerbates tire shouldering. You can mask it with more spring which will resolve the tire lift issue (tire lift like illustrated by chumpy) but the roll is still present however, we can implement more spring to offset the moment lever. Really, we want to stay off of the bump stops and use the springs and valving in the dampeners and ensure the the dampeners are valved with the right blow off.

Here is stock:

http://i788.photobucket.com/albums/yy163/JFastMotorsports/SuspensionResting_zps4b073736.png
http://i788.photobucket.com/albums/yy163/JFastMotorsports/StockSuspensionRCandIC_zpse8790302.png

Figure 3 & 4 is what happened with our DSM, we lowered the suspension by me cutting off a few spring coils to get us to the bumpstops, however, we compromised and took the penalty of accelerated tire wear due to the increased body roll. We were throwing the mass of the car so far out of the roll center it resulted in us lifting a tire.

http://i788.photobucket.com/albums/yy163/JFastMotorsports/Stocklowered2ICRH_zps5125840a.png
http://i788.photobucket.com/albums/yy163/JFastMotorsports/Stocklowered2ICandRC_zps02b2bfdf.png

Now comes the good stuff, Camber plates. So lets say now we install aftermarket dampeners with some adjustable camber plates and we setup the suspension and add a couple of degrees of camber on a stock ride height. Look where a camber adjustment moves the roll center in Figure 6.

http://i788.photobucket.com/albums/yy163/JFastMotorsports/StocksuspensionwithCamberPlateAdjustment_zpsec7715 25.png
http://i788.photobucket.com/albums/yy163/JFastMotorsports/StockCamberplaterRCandIC_zps9d5edb29.png
Now onto the issue you and I were seeing, tire shouldering. Look what happens when you max out the camber adjustment at the plates and lower the suspension 2". Look where the roll center is... Do you see it? Haha, no! You can add a big as spring to counter the length of the roll lever arm, or you can adjust the bump steer and shim the ball joint to restore the designed control arm angle. Once the SAI is corrected you no longer need that big ass spring. It's possible to use a lower spring rate. See Figure 8 for where the RC is. Fast is between the tires :)

http://i788.photobucket.com/albums/yy163/JFastMotorsports/LoweredSuspension2ICandRHwithcamberplates_zpsbfd43 eb7.png
http://i788.photobucket.com/albums/yy163/JFastMotorsports/loweredsuspensionwcamberplateadjustmentsRCandIC_zp s0951992c.png

I really liked the pictures you linked in from Motiq. That setup was really awesome. The thing I liked most about it was that it was a double wishbone suspension. We don't get into roll situations with camber adjustments on a wishbone suspension like we do with McStrut's. They are superior in every way there just really expensvie to maintain because there's more moving parts.

I got rid of the roll and tire wear and require less spring because I'm not throwing more weight out of the body, I'm keeping it in. When the SAI is geometrically corrected like in Figure #1 and the control arm is positioned correctly you dont have to use a big spring to counter the weight bail out.

And whomever asked about the 200 dual springs? I love it. Rides like stock and gets real naughty when I come into the spring crossover.

[vroom4]

Very cool! Well, not the tire wear, but you know what I mean. LOL

Next time out I'm taking a paint pen, doing one lap with horizontal lines across the tire so I can see more of which portion of the tire I'm using.

I try to do this with a infrared pyrometer....not sure how accurate it is...

[Erron Spalsbury]

A couple of things I see in there that aren't really taken into account..
Full doc is here.. http://zzyzxmotorsports.com/library/strut-tech-20070918.pdf

The first is that isn't taking into account the loss of camber while turning the wheel. This is a depiction of a car that rolls 4 degrees. (that's huge, very low spring rate, 200??) There's also no accounting for the sway bars.

I do really like what Steve has to say here, this makes perfect sense.

"For a strut setup, all the theory and my personal experience boils down to a simple set of recommendations:

1. Never lower the car to the point where the inner pivot point is lower than the outer pivot point - what I call "inverted" front lower control arms. Level (e.g. parallel to the ground) is OK.

2. Always set your camber plates to equal positions L/R, regardless of your target camber. Fine adjustments to equal up camber L/F should be made at the eccentric bolt on the strut (if applicable). If you end up with 2-3 10ths of a degree difference L/R, better to leave it as-is rather than end up with a skewed roll center.

3. Target camber for "performance" applications should not be less than -2.5 or so. IMO, -2.0 is not enough camber to maximize grip and on the track will lead to more wear on the outside of the tire. Most (competitive) strut setups I've worked with over the years are at least -2.7, and are as often times around -3.0. Assuming you run zero toe, you should not expect unusual wear with even -2.5 or so. I run -2.7 with zero toe and my Boss is a daily and there's no uneven wear at this point. Same was true with my last Miata; but we know those little guys are easy on tires... :) Unlike some, I've seen no real benefit to "toe out" setups that is worth the additional tire wear."


For my setup, I know what it is. That's the tire that takes the most abuse on HPR as there are more right handers than lefts. It's also the heaviest corner on the car and takes a ton of abuse on the downhill right handers. The right side of the car didn't experience quite as much abuse as the left, I shouldn't have dialed back the camber. I also had a neat conversation with the SCR guys about spring rates. Turns out they are running multiples, as in 4 different spring rates to account for the corner weight miss-match but that's a whole 'nuter discussion.

Vroom4, as I've learned and it sounds like you and I have the same type of IR pyrometer, these aren't the best for tire temps. Since they only read on the surface the temps can vary greatly with just a few rolls of the tire. It's pretty tough to hook a corner and jump right out to get tire temps. The correct way (which I've only had access to a few times) is with a tire probe. We need to see what the carcass of the tire temp is which is a few millimeters down from the outer tire surface area. I was reading 16 degrees difference on the outer edge of mine and I'd bet it was considerably more to be honest. Something like this is what I had borrowed in the past but haven't coughed up the cash for one of my own yet. https://www.pegasusautoracing.com/productdetails.asp?RecID=2515

[mehrshadvr4]

how about caster? more caster should give you the camber you need around corners.

[anyonebutme]

how about caster? more caster should give you the camber you need around corners.

Caster is another adjustment with compromises.

[mehrshadvr4]

I think heavy steering is the only one.

[Erron Spalsbury]

Quick edit from Fridays track session of testing...

http://www.youtube.com/watch?v=Ss4GGXCPwsk&feature=youtu.be

For some reason the HD only shows up if I post it as a link... It's up now in 1080p.

[mehrshadvr4]

Are those tire pieces flying when you take sharp turn? Also I never notice anyone run big camber like puma GTO did. I'm sure puma had their suspension dialed in the best for 3000gt?
5573
ralliart3000gt said the front has negative 6 degree of camber. crazy.

even the rear has tons of camber.
5574

[anyonebutme]

Are those tire pieces flying when you take sharp turn? Also I never notice anyone run big camber like puma GTO did. I'm sure puma had their suspension dialed in the best for 3000gt?
5573
ralliart3000gt said the front has negative 6 degree of camber. crazy.

even the rear has tons of camber.
5574

They also ran narrower tires than we do, the narrower the tire, the more camber it needs.

[Erron Spalsbury]

Are those tire pieces flying when you take sharp turn? Also I never notice anyone run big camber like puma GTO did. I'm sure puma had their suspension dialed in the best for 3000gt?
5573
ralliart3000gt said the front has negative 6 degree of camber. crazy.

even the rear has tons of camber.
5574

Yeah, that's tire rubber. Not mine, but just someones on the track. It's what we call marbles. Rolled pieces of rubber coming off of slicks.

That's exactly right. The Puma GTO guys knew what was up.

[J. Fast]

Yeah, that's tire rubber. Not mine, but just someones on the track. It's what we call marbles. Rolled pieces of rubber coming off of slicks.

That's exactly right. The Puma GTO guys knew what was up.

You Sunday driving in that vid, E? Your 5 seconds off your last NASA trial pace. Looks like your slipping a lot on Danny Lesson and turn 11. Were the drivers side tires significantly hotter than the passenger side?

How did you like the Hawk DTC 70 brake pads? You think I can use them with DOT comps or is that not enough tire?

Sunday... $100 for all day. You're coming right?

Im going to do some outside the box stuff this week man. I'm considering ditching the sway bars all together to see what an independent suspension feels like. Apparently its really grippy. I'm going to load up droop and see what happens when I compress a corner and pull the opposing up with the spring. Will be interesting to see if that setup will behave like a sway but keep the grip of an independent suspension and ditch the tire slip penalty of the antiroll at the tire.

[Erron Spalsbury]

Nah, the car wasn't slipping or anything I was just out testing.(yes, driving like a Nana!) Going deep on occasion (off apex) to throw it in, seeing how much lean I could get out of her. See how much of the suspension I'm using now? I't like hardly 2 inches. :) You gotta ride in it now! It's good stuff. I also had a small thought about the perches popping the outter ring off and kept that on my mind. (Listening for the BANG! Like what happened to Chumpy) I'm really happy with the way the car performed. I'm sure I can take it well under the 2 minute mark now, if I can get this cooling thing sorted out. I'm flat-bottoming and sealing off the engine bay on Saturday with an .063 aluminum sheet. I still don't have tires on it but I'd like to come and watch everyone play on Sunday. When are you heading out there? Are you runnin'?

The pads were awesome, but that's my 3rd day on those, I had those on at Nasa last summer. I think the Torque brake fluid is a winner as well but honestly I had changed the fluid, added the brake coolers and the titanium backing plates all at one time so I don't really know what made the biggest difference.

[J. Fast]

Currently on a hot track. I've. On my third spring setup. First setup was 600lb springs with a 200 lb 1" from bind. Lap average was 2:09. Fastest lap 2:07. Boiled my ATE Blue brake fluid and lost brakes 100% on literally the last lap. Pedal sank all the way to the floor and no brakes! Holy Fuck! When I pit the front rotors were 800 degrees and the rears were 410. Front tire temps were probed at 160 outer and 148'degrees inner. The rears were 150 outer and 135 inner.2nd session... Springs setup at 600lb front and 600 lb rear. Also swapped the brake fluid out for Motul RBF 600. Lap average was 2:05 was experiencing a lot of Oversteer. Rear wars like mash potatoes and really loose. Pit and noticed I was shouldering rears a bit. Rear tire temps were 165 outer and 150 inner. Fronts were 158 outer and 154 inner. Brakes held, lap average 2:04. Fastest lap 2:03. outbreakThird session...dual springs in rear, single 600 in the front. Tire temps were 157 degrees rear outer and 154 inner. Fronts... 168 outer 163 inner (also about 10 degrees warmer). Lap average 2:02.7. Fastest lap 2:01.9.Gearbox is starting to get noisy and grind third too!

[2fnloud]

Jeremy, what struts are you using?

[B-Man]

Currently on a hot track. I've. On my third spring setup. First setup was 600lb springs with a 200 lb 1" from bind. Lap average was 2:09. Fastest lap 2:07. Boiled my ATE Blue brake fluid and lost brakes 100% on literally the last lap. Pedal sank all the way to the floor and no brakes! Holy Fuck! When I pit the front rotors were 800 degrees and the rears were 410. Front tire temps were probed at 160 outer and 148'degrees inner. The rears were 150 outer and 135 inner.2nd session... Springs setup at 600lb front and 600 lb rear. Also swapped the brake fluid out for Motul RBF 600. Lap average was 2:05 was experiencing a lot of Oversteer. Rear wars like mash potatoes and really loose. Pit and noticed I was shouldering rears a bit. Rear tire temps were 165 outer and 150 inner. Fronts were 158 outer and 154 inner. Brakes held, lap average 2:04. Fastest lap 2:03. outbreakThird session...dual springs in rear, single 600 in the front. Tire temps were 157 degrees rear outer and 154 inner. Fronts... 168 outer 163 inner (also about 10 degrees warmer). Lap average 2:02.7. Fastest lap 2:01.9.Gearbox is starting to get noisy and grind third too!

What was your alignment?

[CoopKill]

Just by changing out the brake fluid skews the results, does it not?

[J. Fast]

No, not at all. I ran a full session for 20 minutes and lost brakes just inside of turn 11 on the checkered flag lap. There was enough time in the session to compile useful data... such as tire contact patch, rotor temperatures, tire temperatures, and lap times. Here's my tire contact patch from session number 1. As you guys can see I was giving away 10% of my overall tire contact. You can see how I was folding the tire onto the shoulder and giving away 5/8 of the tread wear area and trading it for the shoulder. Notice the tire wear on the shoulder is also lower than the optimized tread wear tire contact patch triangle on the tire. A little hint here for those guys not familiar with racing... the little triangles on the shoulder of your tires... those are optimum tire contact patch markers. You adjust your suspension to wear inside the marker. You use inner and outer tire temps and get them as close together as possible and then cross reference the tire markers to evaluate your tire contact which translates to effective grip. Session #1 tire patch... http://i788.photobucket.com/albums/yy163/JFastMotorsports/20130623_164614_zpsae3681fe.jpg This was mid day with more spring tweaking... http://i788.photobucket.com/albums/yy163/JFastMotorsports/20130623_123647_zps9d2f1793.jpg ...and then I finally got it right after 8 sessions. Now it's done. This tire and suspension combination has been optimized for ideal tire contact patch. Only fine tuning is required in the future. I shrunk the tire roll patch to just over 1/8", the wear signature is on the optimized grip triangle and the inner and outer tire temps are near identical. Only took 130 laps to figure it out LOL... http://i788.photobucket.com/albums/yy163/JFastMotorsports/20130623_164720_zpse8c3b28d.jpg Let the tires tell you where to make your suspension adjustments ;). Grip is fast and slip is rollerskates.

[familyMAN]

Where'd you end up on camber front and rear?

[Erron Spalsbury]

Very cool! I never saw a reply from ya so I didn't think you were going or I would have come to help!

Tires look good! A few things that come to mind from what I've seen. Did you pull tire pressures? I used to get a 30 psi change from a hot Sumitomo HTRZ2. It made the tire look like it was wearing properly but I was riding the middle quite a bit more. Keep in mind that you'll bend a slick quite a bit more from both the additional traction level and slip angle differences. I found that with a slick I need about 2-3 degrees more camber.

How did the coolant temps go? Boil over at all? I found the stock Mitsu gauge to be a big POS. I've tested 2 so far, the one I had in the car and a spare. One stops at 195 degrees and the other at 197~ish degrees. (using a thermometer that's made for cooking candy on a range top of all things) I couldn't get a good read with the IR pyro, too much shiny in the pan to work correctly.

What were you using for track times out there? Any vids or pics?

[Nihil]

I'm flat-bottoming and sealing off the engine bay on Saturday with an .063 aluminum sheet.

I've thought about doing that with my car as well, to improve cooling and also keep splash/debri to a minimum since it's a DD...curious to see what you come up with and would like to hear ideas. I was thinking of a vent at the rear end of the engine bay with a channel funneling to the rear turbo, in hopes to pull from the cowl, down the firewall past the turbo and on out the bottom of the bay.

So J. what is your final optimum setup then? 600lb 50/50 with fine tuning? That's an 11kg spring? What were your fine tunnings? Looks like I'll be going with a 50/50 split for sure, when I get to upgrading my suspension.

[J. Fast]

Where'd you end up on camber front and rear?
I added two degrees in front and a degree and a half in the rear.

[J. Fast]

Very cool! I never saw a reply from ya so I didn't think you were going or I would have come to help!

Tires look good! A few things that come to mind from what I've seen. Did you pull tire pressures? I used to get a 30 psi change from a hot Sumitomo HTRZ2. It made the tire look like it was wearing properly but I was riding the middle quite a bit more. Keep in mind that you'll bend a slick quite a bit more from both the additional traction level and slip angle differences. I found that with a slick I need about 2-3 degrees more camber. I sure could use your help on Sunday man

How did the coolant temps go? Boil over at all? I found the stock Mitsu gauge to be a big POS. I've tested 2 so far, the one I had in the car and a spare. One stops at 195 degrees and the other at 197~ish degrees. (using a thermometer that's made for cooking candy son a range top of all things) I couldn't get a good read with the IR pyro, too much shiny in the pan to work correctly.

What were you using for track times out there? Any vids or pics? I sure could use your help on Sunday man!
I was using every bit of the 40 minute break to measure this and measure that and adjust. here and and there to get springs swapped. I never experienced any problems with overheating and I decided to revert back to the OEM hood. I did in fact have a piece of aluminum light installed to flat bottom the nose of the car all the way to the firewall. We had a beacon set up that we were pinginig lap times of off. My lap times were pretty consistent around 2:04 without tearing up the tires too much. I did in fact lose 3rd gear entirely around 4 o'clock. The secret to your boil over problem is capacity. Add another gallon or two of coolant. It will take longer to revisit a slice of and give you more time on the track. As you know, I'm using a NASCAR radiator and no fan. It even worked with a stock hood

[mehrshadvr4]

Oh, and no the overheating is still there unfortunately. I know what it is, I've just been reluctant to actually do it.

I was thinking about our radiator and I don't think the setup on our radiator is that good of an design. I'm looking to build a custom radiator for my car where it's dual pass instead on our .75 pass which it's how it seems to be lol. Look at this radiator here. The design is awesome. The coolant doesn't just drop down like factory and some hot coolant actually could reach the radiator outlet. In this design as you can tell the coolant goes horizontally from one side through half the radiator and drops down on the other end and comes back horizontally again to the same side it started from the other half of radiator. this should give plenty of time for coolant to cool down before going back to the engine. The only modification you need to do here is to cut and turn the upper radiator hose/ pipe 180 degree.
http://cdn.speednik.com/files/2012/02/rad3.jpg

[J. Fast]

Lol... Good idea ;)

http://i788.photobucket.com/albums/yy163/JFastMotorsports/DSCN7243_zpsa42242cc.jpg

[mehrshadvr4]

Where did you get that bad boy? I'm actually talking to someone who can make a bolt on one for my car and he can offer upper pipe also if anyone is interested. I already have upper hard pipe from IPS so I'll just need to cut that and weld it again with the end turning 180 degree to face the other way. Maybe we can get couple people interested in this so we can run a group buy on these?

[Erron Spalsbury]

Lol... Good idea ;)

http://i788.photobucket.com/albums/yy163/JFastMotorsports/DSCN7243_zpsa42242cc.jpg

Kinda like the C&R I used to have in my car! LOL

http://imageshack.us/a/img93/5074/radfans.jpg

[mehrshadvr4]

What are you running in your car now?

[J. Fast]

Kinda like the C&R I used to have in my car! LOL

http://imageshack.us/a/img93/5074/radfans.jpg
This radiator is 575 cubic inches. My Fluidyne is 1750 cubic inches. Three times the capacity. The next one I get will have a water to oil cooler integrated.

[Erron Spalsbury]

What are you running in your car now?

Full size all aluminum one. Like the 3sx.

[mehrshadvr4]

Was the C&R smaller in size? I'm looking to make a bigger dual pass using Griffin core. If you are interested I can ask what he will charge for two.

[Erron Spalsbury]

Was the C&R smaller in size? I'm looking to make a bigger dual pass ussing Griffin core. If you are interested I can ask what he will charge for two.

A little bit, yes. See in the pic are the feet towards the top of the image. It was about 2 inches shorter than a stock radiator.

Edit: Yes, please! Two should be cheaper than one, right?

[familyMAN]

Out of curiosity, how much for a third? :) I would like mounts to use my stock fans though (two AC fans).

[mehrshadvr4]

I'll ask him about this. He said he'll look in to see how much the core would cost them he'll let me know. :) We are looking at 2.5" radiator core. I looked at koyo and it's 2" thick so It'll hold more coolant for sure. :D

[Erron Spalsbury]

This radiator is 575 cubic inches. My Fluidyne is 1750 cubic inches. Three times the capacity. The next one I get will have a water to oil cooler integrated.

How did you figure that out without the measurements?

[J. Fast]

How did you figure that out without the measurements? Still has stock radiator mounts. The spread on the stock radiator slot is like 28" and the height of the mounts is 17.5". You have an additional 2-3" standoff on the lower radiator mount and those 13.5" diameter fans overlap into the end tank like 1.5". Appears the actual core is around 25" wide and 14" high. Looks like it has 2" deep end tanks which typically tie to 1.6" core on 2" C&R radiators.

[Erron Spalsbury]

Still has stock radiator mounts. The spread on the stock radiator slot is like 28" and the height of the mounts is 17.5". You have an additional 2-3" standoff on the lower radiator mount and those 13.5" diameter fans overlap into the end tank like 1.5". Appears the actual core is around 25" wide and 14" high. Looks like it has 2" deep end tanks which typically tie to 1.6" core on 2" C&R radiators.

You were close, but it was quite a bit bigger than that.

[mehrshadvr4]

OK This is what we got, the only core suggested by Griffin and Becool radiator fabricators is an 18x15x2.75. He did the drawing and the overall size will end up at 24x15x3 this will cool a 1500hp drag engine or up to 800hp road race engine. As far as pricing he said $780 for one and $580 for three. It would be nice if we can get more people into this to get the price lower unless you guys are fine with this? :) Let me know if you guys are interested in this.

[familyMAN]

I'll have to measure to see if that will fit my setup. Concerned with depth.

[mehrshadvr4]

You should only measure the 2.75" core since the tanks will make it a 3" wide. I will ask him to make the radiator as far from the engine as he can.

[Nihil]

Just a back on track question here, as I'm planning on getting coilovers at the end of the month and have been leaning toward the Megans since they have the mounting bolt for the lines, which seems like they did more R&D than the others.

So, what do these specs look like to you guys? I was thinking of going with 10k all around, since front is 12k and rear is 8k, was gonna go with a 10k at a 50/50 biased setup like what's been found to work in this thread.

Ideas, objections, suggestions? Figured I'd ask here before I go inquiring and spending money blindly, I'm looking for a well handling road course car biased toward over steer rather than under steer. suspension is currently otherwise stock

SPRING RATES:
F: 62mm ID; 180mm length; 12 kg/mm
R: 62mm ID; 200mm length; 8 kg/mm

DAMPER SPECS:
F: 120mm stroke; 260mm length; M2 valving code
R: 115mm stroke; 240mm length; A1 valving code

M2 Valving
5669
A1 Valving
5670

[J. Fast]

The dampener characteristics of those are way different than mine. This is one of the dyno plots for one set of my dampeners.

http://i788.photobucket.com/albums/yy163/JFastMotorsports/JRZTripleValves_zps20341adb.jpg

I put my suspension geometry measurements and weights on a cut sheet and it was designed for this exact stance and a BFG R1 racing tire.

http://i788.photobucket.com/albums/yy163/JFastMotorsports/RaceSetup_zps95f618ad.jpg

I can offer no opinions on the Megans as I went down a different road and have never been in a vehicle with them setup properly.

[Nihil]

The dampener characteristics of those are way different than mine. This is one of the dyno plots for one set of my dampeners.

http://i788.photobucket.com/albums/yy163/JFastMotorsports/JRZTripleValves_zps20341adb.jpg

I put my suspension geometry measurements and weights on a cut sheet and it was designed for this exact stance and a BFG R1 racing tire.

http://i788.photobucket.com/albums/yy163/JFastMotorsports/RaceSetup_zps95f618ad.jpg

I can offer no opinions on the Megans as I went down a different road and have never been in a vehicle with them setup properly.

I'll admit I don't know how to read the charts, that's why I posted up those, so someone else can observe and compare.

Also, since you posted a picture of your car, do you rub at all, being that low? You DD that car, don't you? It looks really low like you'd rub and looks like your tires stick out enough, that if you hit a pot hole you'd eat a fender, though it's hard to fully tell from the side shot

[J. Fast]

I do not rub the fenders or bottom out. I have to put 1,800lbs on a corner to bottom out. Theres just not that much weight to transfer from the adjacent corners. The highest estimated load on a corner I expect to see is roughly 1,000lbs. That's the max load rating on the tire before it deforms ;). That's 1.5" of suspension travel for me, plenty of room. There's 2.5" of compression travel till an additional 250lb bump stop.

The big thing to look at on the valving is wether or not the wheel rate will blow thru the valving at speed. If your valving tapers off to early or is too low the dampeners won't attenuate the spring/wheel travel and you'll smack the bumpstops and overwork the dampeners.

[Nihil]

I do not rub the fenders or bottom out. I have to put 1,800lbs on a corner to bottom out. Theres just not that much weight to transfer from the adjacent corners. The highest estimated load on a corner I expect to see is roughly 1,000lbs. That's the max load rating on the tire before it deforms ;). That's 1.5" of suspension travel for me, plenty of room. There's 2.5" of compression travel till an additional 250lb bump stop.

The big thing to look at on the valving is wether or not the wheel rate will blow thru the valving at speed. If your valving tapers off to early or is too low the dampeners won't attenuate the spring/wheel travel and you'll smack the bumpstops and overwork the dampeners.

How did you go about figuring all of your weight transfer out? It sounds like you've broken down everything into variables and figured out how to calculate your requirements.

Your shock dyno appears to be softer than the Meagan's, so I'm gonna guess I'll have the valving required?

I live in a rough roaded town, so it'd be nice to be able to calculate all of this so i can know how much I can lower and still take pot holes and such. I don't wanna have to screw with ride heights/spring rates dd vs track, I can sacrifice street drivability for track drivability. My front tires stick out a little so if I were to go too low and bottom out, I'd eat a fender.

[J. Fast]

I figured everything out by measuring and building a template... like this one http://farnorthracing.com/newimages/marked_sheet.jpg. http://farnorthracing.com/newimages/plumbob.jpg I Pretty much followed Dennis Grant's formula for modeling and planning to build a professional suspension and used WinGeo 3.5 to build a model. From there I found my own way. A good starting point was this little gem Autocross to Win (DGs Autocross Secrets) - Suspension (http://farnorthracing.com/autocross_secrets5.html). Once I collected all the info I had the data entered in a dynamic calculator like this... Autocross to Win (DGs Autocross Secrets) - Dynamics Calculator (http://farnorthracing.com/autocross_secrets16.html) . Positive results followed as expected.

[J. Fast]

Something doesn't look right to me regarding the dampener plots Nihil posted. It's typical to see more rebound bias in dampeners to offset the springs. Compression dampening typically dampens unsprung mass and rebound dampening assists sprung mass. In a two degree of freedom system the springs and dampeners are coupled in compression so the rebound force should equal the total opposing forces. Is this not correct? The Megan dyno plots appear to be way off. They bias for compression (positive force on the shock dyno) and do not account for the weight of 1000lb corners coming out of compression. They only bias rebound for around 150lbs of force?

http://www.3sgto.org/attachments/transmission-suspension-drivetrain/5670d1373767804-our-suspension-setup-correctly-aftermarket-strut-mfrs-bias-correct-a1.jpg

[Nihil]

That's what I was wondering...Kinda understand the graphs, just don't know what good vs. bad is. So what you're saying here, is, and as I observe it, compression is going to be stiffer than the rebound, so, it'll take more force to compress and less to rebound, slower compression stroke and quicker rebound stroke, correct? Yours show closer to a 50/50?

Speaking from moto suspension, you typically run a more firm compression and less firm rebound, to get back to full stroke quick enough to absorb the next obstacle, though cars aren't going through as much obstacles unless offroad. So I don't know how far off meagan is or what's good vs bad.

[J. Fast]

Here's a few alternatives measured and spec'd to our chassi.

Fortune Auto 500 series: 91-99 Z15A Z16A Mitsubishi 3000GT 4WD 500 Series - Fortune Auto Coilover Superstore (http://www.fortuneautocoilovers.com/shop/91-99-z15a-z16a-mitsubishi-3000gt-4wd-500-series/)

http://www.fortuneautocoilovers.com/wp-content/uploads/2013/03/Fortune-Auto-Shock-Dyno.jpg

Bilstein:

http://i131.photobucket.com/albums/p297/josh18_2k/LS1%20FC/Bilstein3000GTStrut.jpg

Their bias to rebound is significantly different than the Megans. Megans are opposite.

[Nihil]

That makes more sense for a car. Though, what spring rates are their valving charts set up for? I'd think, with a car, the suspension is a lot slower so more rebound vs compression would make sense

[J. Fast]

When you compress a 600lb spring 2" you load 1200lbs on it. You want to have the rebound bias to unload the spring smooth so you don't blow thru the valving. The bilstein plot is for stock springs. 300lb springs with 100lbs of compression so like 400lbs till rebound blow off. If you install double the spring rate you want to double the valving. No shocks on the market do that. A 700lb spring should have rebound bias atleast equal or greater. Megans are not an upgrade when I look at the dyno plot at all. They have no bias built-in to unload the springs. They are too soft in rebound to hold the corners down. On paper they appear to likely induce bounce.

[Nihil]

I agree, they seem to be bouncy. I'll have to track down more graphs for the other common brands.

[familyMAN]

First time I have seen the fortune auto. What do you think about those as a budget coilover?

[J. Fast]

Fortune valving looks pretty good.

I found another shock dyno online published by Fat Cat Motorsports with valving for off the shelf JIC FL2- TAR's for the Z16A (2006). I can translate it using the averaging method and re-plot on a standard shock dyno graph.

From what I'm seeing on the graphs, the JIC hysterisis is really small and there's not big spikes or anything. My take after seeing the empirical data is Dennis Grants little rant regarding aftermarket suspensions a few years ago was a little hyped. I could see it being justified with the Megan's because the valving is absolutely miles off for the spring rates but for the most part every dyno plot posted in this thread (with the exception of Megan's) looks pretty good.

Here's some more good info and a full cycle plot of JIC's not using the averaging method.

http://i788.photobucket.com/albums/yy163/JFastMotorsports/JICDyno_zpsa8cc360b.gif
EDIT: I also forgot to mention I have dyno plot info on the TEIN EDFC adjustables as well. If I get some time I'll post those charts up also and combine everything for our specific chassi on one dyno chart like the dyno take 2 Toni has, except it will be for dampeners (hopefully fronts and rears). KW's and Ohlin DFV's... I have that data also :)

[J. Fast]

Here's some empiricals from Greg Haye @ GT Motoring


This first average plot is for off the shelf KW's. Blue line is the front and the Black/Grey line is for the rear.

http://farm8.staticflickr.com/7289/8738899195_7021212bed_b.jpg


These are Ohlin DFV off the shelf valving. Blue line is full soft with low speed bleed in road setup. Grey line is full hard in track configuration.

Fronts:

http://farm8.staticflickr.com/7285/8738910139_8592e35ee7_b.jpg

Rears:

http://farm8.staticflickr.com/7286/8738910099_29c01cfa9e_b.jpg

KW's front to rear's look like they might be difficult to phase together. Off the shelf Ohlin's look much better and are closely resemble the valving for my JRZ's and Muellerized setup on my red 2G.

I've never been in a KW appointed 3/S but have some immediate questions with the front to rear progressive/digressive bias. Anyone have any ride and/or track feedback for the KW's?

[Erron Spalsbury]

Cool, I knew something was up with the JIC's.
Somewhere I have the dyno plot from mine from a few years ago.

[Nihil]

This is all very interesting to see. I emailed a couple of the typical coilover mfg's asking for dyno/spec sheets, I doubt I'll get any from them, general consensus is, they're all made in the same plant, including the Tein stuff.

[DocWalt]

Honestly, the Megan damping curves look no better than $350 Raceland coilovers. Ignore the forces, that damping is for much softer springs for a Miata. Raceland Dyno Test Results - Miata Turbo Forum - Turbo Kitten is watching you test compression. (http://www.miataturbo.net/suspension-brakes-drivetrain-49/raceland-dyno-test-results-54067/)

Having ridden in a car with Raceland coilovers back to back with Bilstein shocks, the lack of rebound damping is incredibly noticeable. The car feels like it wants to leave the pavement a lot, which can't be good for grip.

[2fnloud]

^^^^^Ninja Edit^^^^^^

Saw the E-mail and was like:
http://4.bp.blogspot.com/-cYRX_xZ1Xho/T_J4kv8Ro8I/AAAAAAAAKao/AT3APZhp3S8/s1600/What+You+Talkin+Bout+Willis+Picture.jpg

[Erron Spalsbury]

^^^^^Ninja Edit^^^^^^

Saw the E-mail and was like:
http://4.bp.blogspot.com/-cYRX_xZ1Xho/T_J4kv8Ro8I/AAAAAAAAKao/AT3APZhp3S8/s1600/What+You+Talkin+Bout+Willis+Picture.jpg

Ya, the first inch everyone seems to forget about the weight of the car but since we're talking specifically shock dynos now I figured I'd keep the curve ball out of it.

[sergechronos]

Ya, the first inch everyone seems to forget about

Well it can be rather forgettable. Giggity.

Anyhow, looking forward to the charts for some of the other coil over options. Should see if Apexi has one for their Evo S1s since they're supposed to be fairly comfortable and better handling. Would be interesting to see how it measures up

[JasonY]

For quality shocks, it usually steps from OEM straight to something along the lines of Ohlins. The stuff in the middle is usually a downgrade from a healthy OEM setup.

Jason

[J. Fast]

For quality shocks, it usually steps from OEM straight to something along the lines of Ohlins. The stuff in the middle is usually a downgrade from a healthy OEM setup.

Jason Only true if 65% critical dampening can not be achieved with valving and spring combinations. Take a look at some of the shock dyno plots and see if the rebound and compression are equal to each other in low speed ie. 3-5 in/sec range. When you take into account the critical dampening equation with spring rates and corner weights if the number falls between 62-68% then you've got yourself a good setup :). Those Fortune Auto shocks actually look pretty good on the soft settings and the reason why the Bilstein's ride so nice... they are rebound and compression matched at 3 in/sec at 65% critical dampening for a full weight car on stock springs ;). The only way to know for sure though is to measure, disassemble, and weigh the suspension and wheels to get the sprung and un-sprung weights, geometry, and the motion ratios. When I calc'd the critical dampening for the Fortune Auto's I determined the spring rate I'd want on a 3/S with that valving is 485 front and 540 rear. Notice the rear spring rate is higher... there is a reason. With some new found knowledge IMO any coilover with a spring rate over 10K that doesn't valve a median at least 220pounds at 3 - 5 in/sec in rebound and compression on our corners isn't 65% critically dampened nor a performance improvement. The secret sauce to coilover setup is 65% critical dampening in both compression and rebound. For the most part only high end dampeners can achieve that because they have independent adjustment for both. However, if you can spec your dampeners to be 65% critically dampened for your specific spring rates then you have something special. Unfortunately, every time the weight distribution, geometry, and un-sprung mass is changed the dampeners need to be re-valved on one ways to maintain balanced critical dampening on the non adjustable side. If you select a dampener MFR with domestic USA support that can custom valve then midlevel coilovers aren't necessarily a downgrade.

[2faststealth4u]

Wow Jeremy good write up on this issue.. Never learned so much about a cars strut system an balance in my life O_o

[Nihil]

Ksport wrote me back, it costs $35 bucks to get a dyno sheet, they have to actually test it. They said their circuit pro series comes with a sheet upon purchase.


We can offer a shock dyno service for $35 per corner if you’re interested. Dyno sheets are not readily available for every application of our Kontrol Pro coilovers due to there being several hundred applications. Shock dyno sheets are included with purchase of our Circuit Pro coilovers.



Regards,
Chris M.

Here's a dyno sheet of the BC Racing stuff, not sure what for though. It seems most of the dyno sheets available online are a generic, unrelated to a specific shock platform, sheet.

5755

[fastfalcon94]

Has anyone looked into ISC coilovers? I don't know if many 3000gt people run them but they are quite popular on the subaru platform. I have them in my suby and I really love the way it handles. I'm not a serious track racer though, and I don't know a whole lot about shock dynos. I've just done a few autocrosses for fun. But ISC's are supposively made in MA so maybe they would be willing to work with someone on custom spring rates or dampening. They were able to get me sti coilovers with different top hats for my 98 impreza, and special rear adjustable camber plates.



Shock Dyno Results | ISC Suspension NA (http://iscsuspension-na.com/coilover-photos/shock-dyno-results/)


ISC COILOVERS (http://www.isc-performance.com/)