C2 suspension analysis Mitchell "Racing By The Numbers"

[Jerry G.]

Has anyone used the Mitchell software to analys the C2 rear suspension geometry? i'm working on an oversteer problem that i think is caused by bump steer and bump setting on the shock interaction. The method to model the Corvette trailing arm suspension is a little tricky. Just looking for someone that has already done the measurement for data points. Jerry

[Dick W.]

Re: C2 suspension analysis Mitchell "Racing By The Numbers"

Have not, but as I understand it, the later rear strut bracket on the differential will lower the mounting somewhat and may offer a little help. Are you running a rear sway bar??

[James G.]

Re: C2 suspension analysis Mitchell "Racing By The Numbers"

FRANZ ESTEREICHER was one of the rear spring engineers. He was the North American Rockwell Suspension Engineer (GM Engineer) who was on the design team for the C2 rear spring and many, many more on the Corvette Platform. He also designed the AMC TRANS AM race suspension in 1970-72 era. I have his conract info Jerry. Send me a PM if you want to visit with him. DICK GULDSTRAND is also very sharp even after his 84th birthday on December 1st.

[Clem Z.]

Re: C2 suspension analysis Mitchell "Racing By The Numbers"

all you need is this and a floor jack. http://www.google.com/products/catal...ed=0CDwQ8wIwAQ#

[Duke W.]

Re: C2 suspension analysis Mitchell "Racing By The Numbers"

I'm not familiar with the software you mentioned.

The '63 Corvette "three-link" suspension was sophisticated for its time, but is not a very good design by today's standards. The high roll center (I recall its about 7" above ground with the OE tires.) yields high roll stiffness from the springs, which is good, but the high roll center also causes a lot of toe and camber change with suspension movement.

The '68-up rear strut rod bracket lowers the rear roll center a couple of inches, which helps, but if your rules don't allow major changes to OE suspension components, that's about as good as it gets.

Modern suspensions have five links - either independent or two A-arms and a toe link and roll centers near ground level. When you think about the fact that a free body in space has six degrees of freedom, it takes five links to limit it to one degree of freedom, which is what you want.

In my experience driving C2s and riding in C3s they all have a tendency toward oversteer at the limit. This can be mitigated by installing hard urethane bushings on the front anti-roll ball links or, if allowable by your racing rules, heim joints. Then use more compliant bushings on the rear bar links. This will tend to decrease rear roll stiffness with increasing roll and mitigate the oversteer-at-the-limit situation.

Getting both jounce and rebound shock valving right is also critical to stable limit handling.

Duke

[Jerry G.]

Re: C2 suspension analysis Mitchell "Racing By The Numbers"

Already have one. I know what the problem is (i think) The question is how to get rid of it.

all you need is this and a floor jack. http://www.google.com/products/catal...ed=0CDwQ8wIwAQ#

[Jerry G.]

Re: C2 suspension analysis Mitchell "Racing By The Numbers"

Jim , I tried to send you an email through the NCRS board and it bounced back?? I would like to talk to Franz. The "been there done that" guys are great to talk with. I'm at jfgollnick@aol.com

[Steven B.]

Re: C2 suspension analysis Mitchell "Racing By The Numbers"

Jerry, I am not certain all you are running but if I remember you have a small block. When running an AP (C3) Corvette we had a similiar problem near the limit. We ran Guldstrand springs up front and in back (BB, not Daytona), Greenwood Koni adjustables (set mid point to full depending on track), 1 1/8 bar up front with aluminum bushings, 7/8 bar in back IIRC, and Guldstrand's recommended competition settings. Tried usiing the autoX settings on a short track but didn't work as well as comp. settings. This minimized the problem, but did not fully eliminate it. We also ran Bilstein's with little to no change. I recommend calling Dick and Franz, also. Dick was very helpful a number of times.

Steve

[Clem Z.]

Re: C2 suspension analysis Mitchell "Racing By The Numbers"

have you already corrected the bump steer in the front ???

[Steven B.]

Re: C2 suspension analysis Mitchell "Racing By The Numbers"

Jerry, along with Clem's question for your steering what are you using for center section and sleeves? Stock?

Steve

[Jerry G.]

Re: C2 suspension analysis Mitchell "Racing By The Numbers"

I've got it down to about a .003 inch change from full droop to full bump.

[Jerry G.]

Re: C2 suspension analysis Mitchell "Racing By The Numbers"

Steve Not sure I understand the question. Which components?

[Steven B.]

Re: C2 suspension analysis Mitchell "Racing By The Numbers"

Sorry Jerry. I think things and don't always say them. I was referring to tie rod sleeves/ends and center section. We had some trouble fine tuning and changed to some heavy duty custom made sleeves and it helped a bit, after we did everything else I mentioned. The stock components allowed too much slop possibly due to wear. It sounds like you are narrowing it down.

Good luck!

Steve

[Clem Z.]

Re: C2 suspension analysis Mitchell "Racing By The Numbers"

remember with rear steer cars you need a very stiff tie rods because you are pushing to turn the outside wheel into a turn. the tie rod is under compression and can act like a piece of cooked spaghetti

[Jerry G.]

Re: C2 suspension analysis Mitchell "Racing By The Numbers"

Yes everything is custom made heavy duty tubing with heim joints at all connection points .