First gen Camaro suspension 3D plot?

[j-rho]

Hello,
Has anyone fully plotted out the first-gen Camaro's front suspension in 3D? Such data would be plugged into a suspension analyzer to figure bump steer, camber gain, roll center, motion ratio etc.

I'm considering putting together a first-gen Camaro for national-level autocross competition in a class with a set of allowances that would likely seem odd to most here, and where most of the common bolt-on aftermarket solutions or old tricks (Guldstrand mod) would not be ideal or legal. I believe the car's biggest handicap in the class I'm thinking of running is its front suspension geometry, so I am interested to see, before diving in, to what extent this handicap could be mitigated through the rules allowances the class affords.

Have spent many hours searching and reading various sites and forums in advance of this post, so I already owe thanks to David Pozzi and many others for their contributions. So far all I've been able to pick up is a KPI around 8.2 degrees, 0-3 degrees caster from the factory, and a performance-unfavorable camber curve.

Thanks in advance,
Jason

[David Pozzi]

F Stock???

[j-rho]

STX. Suspension rules same as ESP. We're allowed to change control arms now.

[David Pozzi]

I'd say, if you can't improve the camber gain, don't do a first gen. Also the amount of wheelwell room is more limited than on later models.

I'm not up on this STX class, and it's been years since I ran in ESP, - 26 years to be exact!

[j-rho]

Hi David,
In STX 2WD cars are limited to 9" wide wheels and 265mm tires. I think I can fit those at all four corners. Tires are limited to 140-treadwear, ruling out Hoosiers, though today's best 140 tires are darn close to Victoracers. Engines limited to 5 liters.

We can replace the upper *or* lower control arms, but not both. We can't change ball joints, spindles, or suspension mounting points. Springs and shocks are free. Can replace all bushings, offset if desired, no spherical bearings.

There are some nice adjustable aftermarket upper control arms out there, but I haven't found anything adjustable for the lowers. Since I can only do one or the other, was thinking maybe of doing some custom LCA's to get all the camber and caster needed, with each independently adjustable. One could shorten or lengthen the upper arm slightly with offset bushings. With a lengthened LCA in proportion to a slightly changed UCA I'm thinking a workable camber curve may be obtainable. Hence, interested in the stock geometry to see to what extent this is all possible.

The car would be basically just an autocross toy, sprung very stiffly, so the camber and bumpsteer curves aren't as important as they might be in a track or street car; I don't plan to let the suspension move much. Would be nice to not have to run 4 degrees static negative camber like a darn strut car though...

[David Pozzi]

With a lot of static neg camber it would help get around the poor camber curve. A 255 can fit, maybe a 265 with some work. Lowering the car a lot will help you get into the better part of the camber curve too.

I'd do an adjustable upper arm, you can get more neg camber with it and lots of positive caster.

[j-rho]

Car will be very low.
One could conceivably achieve the desired amounts of caster and camber with an adjustable lower arm, no? In theory, lengthening the lower arm as opposed to shortening the upper arm should "smooth" the camber curve. Could play around with offset bushings and shims in the upper arm to get everything happy.

Was hoping somebody already had the car's numbers out there for susprog3d or wingeo. Oh well, trial and error works too!

[David Pozzi]

I have them for Performance Trends Suspension Analyzer. I don't have exact steering locations though. I could be wrong but I doubt there will be much difference between a longer lower arm or shorter upper since it's only a small length change. Do the C3 Corvettes fit in this class? They have better F/R weight balance.
David

[j-rho]

Cars have to be 4-seaters unfortunately.

If you wouldn't mind sharing those values, beer is on me if we ever meet up at an AAS event, or should you ever make it to So Cal for an autocross... [email protected]

[Stu Seitz]

I have them for Performance Trends Suspension Analyzer.
David

Is there any way you could output those in a excel format?

[David Pozzi]

It does a couple of different outputs, I don't know much about them.
I'm working hard on a car right now so it might take me some time to get it done.
David

[j-rho]

David, if there's a native file type for your software, that would work for me. They have a demo version of their SW and if it looks like I can do what I need with it, I'll just buy their SW.

[David Pozzi]

You can run their demo for 2 weeks per computer. Everything works during that period. It exports the file in 3 or 4 different ways, or just copy the dimensions. F/R dimension is relative to the spindle centerline I believe.

I can send you a file, pm me your email address.
I can't guarantee my measurements are exact however.
David