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)



Corner weights of track Evo


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

Evolution IV-IX Coilovers/Springs
Welcome to Muellerized Suspension Systems

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

[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]

Bent frame? lol

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

[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.

[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...



This is from a friend (Ray's camera Jer)..


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.



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.

[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 ?

[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