Interesting topic.
Do you have by any chance a picture of the cars and of the test rig ?
Also, it may be a dumb question, but what arm's length do you use on each cars ?
I'm currently doing the same type of research on my car too. I'm too trying to know the stiffness of the leaf spring. I tried to calculate it via the stiffness tables at the end of the manual and motion ratio, via simulation and via 2d beam calculation.... 3 different results...
Thank you