my front and rear wheels will be a 1/8th or 11/16th of an inch from my fenders. i need help picking out the right spring rates so my wheels dont hit my fenders during wheel travel. thanks in advance

 

errr, is that 1/8th OR 11/16th, like you are choosing between the 2? or do you meant 1/8th in the front and 11/16th in the rear. Or is that a typo and you mean like 5/8th?

Just to amuse myself, I'll do the calculations. So the necessary static deflection (bump+droop travel) is related to the wheel rate, or the natural frequency of the suspension.

Here is a good calculator if you can find info for the v36. I can fill it out for the v35 sedan, but not interested enough to look up your car. http://www.racingaspirations.com/whe...ncy-calculator

So for a 11/8" static deflection, you would want a wheel rate of about 2.66hz. If you wanted your static deflection to be 1/4", you would require an absolutely incredible 6.3hz.

You want your rear wheel rate to be about 10% higher than your front. Plug in your v36 data and calculate it out. Just as an example, in my v35 sedan to achieve wheel rate of:

F: 2.66hz, R: 2.9hz would be F:1300 LBf/in R: 1450 LBf/in
F: 6.3hz, R: 6.9hz would be F: 7000 LBf/in R: 8000 LBf/in

For some comparison, a stock g35 has wheel rates of 1.3/1.4hz. Track only cars with little to no aero component generally run about 2-2.5hz, and it will be pretty rough.

These spring rates are totally unrealistic. You probably want to increase your bump travel, like airbags or something, or you might want to find and run the stiffest bump stops you can possibly find, and you probably have to preload and have your car sit on your bump stops at rest for it to give enough effective spring rate to prevent your tires from hitting your bumper. Running such high rates though, will not be kind on your pillars or frame.

 

What kind of roads do you drive on, and how much wheel travel do you need?