Have you consider the fact that in a "way more travel" situation, unlike in a solid axle you are narrowing the between the wheels distance???

your center of rotarion of the arm is given your radius is small beeng the length of the arm so after a point, each centimiter of downward travel will jave a huge impact on that distance..

( jyst for arguing purposes only!!!)
Hope this dosent sound much Greek to you
since I dont remember how its called the distance between the two wheels <img src="/forums/images/graemlins/smile.gif" alt="" /> <img src="/forums/images/graemlins/smile.gif" alt="" /> <img src="/forums/images/graemlins/smile.gif" alt="" /> )