Calculating Antisquat, need spring rates

I was talking to an automobile engineering friend of mine and asked him about calculating AS and this is what he came up with:

You need to know the CG height, wheel base, front and rear suspension stiffness. Also, you need to find the virtual trailing arm point. You do this by looking at the sideview of your linkages, and extending them to find a virtual intersection.

For 100% anti-squat:
e/d = h/L + h/L*(Kr/Kf)

e = height of virtual trailing arm point
d = distance of virtual trailing arm point ahead of contact patch
h = center of gravity height
L = wheelbase
Kf = front ride rate
Kr = rear ride rate

Usually, you approxiamate Kf = Kr:
e/d = 2*h/L

The only difficult measurement is "h"...
If you had some scales, with the ability to raise one set of scales, and use some geometry, you could figure out "h"... or you could guess

How far off is this? Then does anybody know the spring rates of a set of 3" Rustys coils that are approx 5 years old and a stock Cherokee main leaf with Dodge Dakota springs minus the main dodge leaf?

Thanks,

AARON

The rule of thumb for finding CG (h), is that it resides at the top bellhousing bolt. It may not be 100% exact, but will be close enough for most of our uses.

So your equation brings up a question: What does spring rate have to do with anti-squat? Is it only in reference to leaf spring suspensions? I have gotten so caught up in the front suspension geometry, I have not looked into the rear (that was my next step).

Steve

Its not spring rate but spring Ride rate. I didnt realize that at first, its the spring rate at the tire. I still dont understand why its needed but my friend was an engineer for GM for a few years until he left and now works for Contential tire and just reciently started up his own import speed shop. I have a link to where I was posting this question: http://www.p1auto.com/forum/viewtopic.php?t=57

AARON