BEPUphysics

well the whole point is that the vehicle shouldn't pass unless its carrying weight, increasing the frame rate helped, thanks norbo for your help

here is some pictures i hope it explains http://img52.imageshack.us/img52/5766/10723040.png http://img252.imageshack.us/img252/6590/80346814.png when the vehicle hit the yellow wall it likes push it down ward that would be understood if the vehicle and the wall smooth edges but they have a rough edg...

in my game i have a vehicle and a kind of low ceiling that the vehicle is not suppose to get under, but when a collision happens the vehicle kind of slide under ceiling, i dont want to play with the wheel suspension constant, another thing when a box fall onto the vehicle the box kinda sink through ...