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

[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 ?

[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...kUCy9S9wqNxcnw

[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 ?

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...kUCy9S9wqNxcnw

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.

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.