TTT, any more info Clutchdust?

 

When he says EXACT location he means EXACT locations. If you are not measuring to a least a 1/16" of an inch for a street car (you need to be within .010 on a race car) the simulation results will be meaningless. You also need to use the measurements from your own car. C3's are 20 to 30 year old production cars and measurements will very from car to car. Also suspension ride heights will affect measurements. Take 2 cars with a fender height of 28", one with F70-15's and one with P225/60/15's that have different spring heights but the same overall height. The 2 cars will have different roll centers and different center of gravity.

Designing suspension is no different than designing an engine. Would you measure the bore or bearing clearences with a tape measure? I know that everyone is trying to help but one post says the front hub to rear hub is about 100". C3 Corvettes have a wheelbase of 98". Being within 2" is going to give you very unreliable data from a computor simulation package. If you are going to get any kind of reliable information to base changes on you need to dismantle YOUR car and measure everything.

 

Yup...

If he doesnt have ANY of the measurements... just getting a ball park of everything lets the progression continue.

Then again, I mock up everything a couple times before I finally assemble it!

 

Sometimes, the more ya play with 'em, the more fun they are to drive!!!

 

wow! i get tied up for a week and my little thread here kind of takes on a life of its own.
thanks for all those that replied. i will check out the numbers supplied and see if those will give us some good baselines.
pete, i understand what your saying, and i agree. however, there are some glaring deficiencies inherent to the c3 design. some of these deficiencies aren't going to be significantly better if one car measures 1/2" more of this or that than another car.
it's kind of like target shooting. when you know your off, you make big changes to get you on your target, then you can dial it in.
as norval and TT know, the original design is way off the target. plugging data in from our 40 year old design into a modern computer program and letting that do the figuring will likely get me closer to the target with less fuss.
the last thing i want to do is disassemble the car to take freakin' measurements. if i do that, the thing will be down for years. i'd rather take some generic numbers and get that big, whopping deficiency down to a noticable improvement than disassemble my car, wait for a few years (life tends to get in the way of these things, you know) and get dead perfect measurements for a car that is just and always will be a street car.
i'm not talking about picking up .10ths on the track here. i just want to make the car more predictable and fun to drive.

 

Clutchdust what are you really trying to do?? Feeding numbers in a program is going to get you what?? Are you after a roll center??? Bump??? What???
I attacked all these problems without number crunching. Go to the car and start measuring what you have, make a change, again measure what you have and see if you are going in the right direction.
I repeat, what are you trying to do?

 

norval, i'm enlisting the help of a friend who is an engineer. he has the program. he'll be doing the fabricating. he just needs to know what the suspension actually does. i've been telling him for the last year the cars don't gain enough negative camber and have too much bump steer up front and have too much toe change in the rear. but he's an engineer so that means nothing to him. he needs numbers to see what is going on.

 

I don't agree that he can just crunch some numbers and come up with a fix for you. The thickness of a washer can make a big difference and he will not know how to calculate it .
If you are going after bump start with a tape measure, whittle it down until you get in the range for dial indicators. You will need longer tie rod sleeves, an adjustable outer shimmable tie rod and some way of shortening up the inner drag link. After that it involves making a change, checking toe, making change , checking toe etc etc until you get it as close to zero as you can.
Roll center and camber gain are spindle length or inner upper A arm mount.
Are you really ready to go into all that? It involves alot of testing, time and fabricating.

 

This is how I worked the center link. I welded a piece of steel to the top of my drag link and yes you can weld suspension parts if done right. This bar is about 3/4 inch thick, 4 inches long and it was welded full length both sides and all the way through. I then drilled and reamed with a special 7 degree taper 3 new holes each 1 inch in from the last one.
In total there are 4 holes including stock which allows 4 different length tie rod sleeves.
I did this to both sides. I also built my own adjustable outer tie rod end with a pile of washers, only for testing, the final length is a solid piece welded to the steering arm/ an a through bolt, not relying completley on the weld.
Sorry to mess up the post with the large picture