Bent Wrench wrote:
Don't I need to know where I am at before firing up the welder?
absolutely
Bent Wrench wrote:
And the steering geometry surely can be modeled to discover correct rack placement?
yes. there are some basic rules to get decent placement without an actual model but this is the best scenario.
Bent Wrench wrote:
And how will harrowing the Supra rear section affect the geometry?
that's the real question. check out vsusp, it's a free online program that will give you results if you know what to feed in
Bent Wrench wrote:
My plan is an autocross beater on street tires and 250 to 350 HP and under 2200#
if you're building from scratch you should be able to make it much lighter than that
What you've posted here that you want better handling that what you have (I don't know what you have though, presumably a supra if that's what you're modeling after) and that you want to use suspension components off of the car (I think?) but may move around pickup points to avoid cutting springs. That's all really kind of a mess.
If you're building a new chassis you're better off figuring out what you want the suspension to do then modeling and building a suspension that will do what you want instead of trying to use some components from an existing setup that may or may not meet your end goal, or may create too many compromises.
Do you have numbers you're looking for? body roll limits, camber loss per degree of roll, camber gain per degree of bump, roll center heights, roll axis inclination? Anything?
There are absolutely ways to figure out what your current suspension is doing if you know the geometry measurements. Then if you have parts you want to keep you can use those same parameters and change around chassis points and whatnot but you always have to keep in mind what you intend for the suspension to actually do.