rear suspension geometry software

jbaker

Member
Joined
May 26, 2001
working my way thru my rear suspension. i will be revising
the instant center point. does any one have access to software to predict the effect of changes
thanks jerome baker
 
Greetings,

The information on this site is well-depicted, but I'd advise caution about some of the heights shown. GM designed the rear lower control arms to be nominally parallel to the ground under a normal load/trim condition, which I confirmed to a tolerance of about 0.1". (I'm curious about the determination about the center of gravity height: how was this obtained?)

Getting the suspension pick-up point heights properly measured is very important for the G-bodies, because the upper control arm swing length is extremely short, so minor errors in height can create big errors in calculating anti-squat behavior.

This isn't a criticism of the information shown on the site, btw: the owner probably correctly measured his car. But I do suspect that the initial height of this car was higher than normal - hence my caution.

Best,
MAP
 
oh i didnt know that. i just found it last nite and it looked pretty informative. i dont know what half those words mean. LOL:D
 
Quote:
"This isn't a criticism of the information shown on the site, btw: the owner probably correctly measured his car. But I do suspect that the initial height of this car was higher than normal - hence my caution."

The site in question is mine. There are two sets of graphs, one is my car which has been lowered 1" to 1.5" over stock with stiffer lowering springs for handling. The "Stock GN" graph was developed from my car by raising the plot of my car approx. 1.5" (I don't remember anymore). Since then I have had the opportunity to measure several TR's and the the lower arms on a stock TR are not parallel to the ground and the IC is behind the car (w/ no driver) which has been verified by measurements of other GN's/TR's. I have not redone the "stock" graph to show these new measurements tho so it could be off a bit. Every car is different and should be verified on its own so don't use my #'s for your own calculations.

The center of gravity can be calculated if somebody wanted to spend the time doing it and had access to wheel scales but for most door slammers the camshaft height serves as the CG height. This is a good reference b/c even if it veried by 2" the overally affect is very small compared to the precision needed to measure the heights of the control arm mounts just as MAP mentioned.

Hope that clarifies some things..
ks;)
 
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