Dx- if you had a speedmerchant you would not have to worry about that! lol, jk. I would just make sure that you use a steel screw that is the proper lengh (maybe the one they provided was too short possibly). or you could adapt speedmerchant side links to that car and get rid of the mile high roll center and flimsy piece all together.
also are you runing a front bumper (solid one, not foam), if so remove it, since it causes more problems than it cures. if anything run a small foam bumper the width of the front of the chassis (ie, it doesnt extend infront of the wheels), and it will save your body a little bit, but a hard chassis bumper is a really bad idea in 12th scale, since instead of the body abosorbing the hit gradually it takes it all in one big blow, and you cant glance corners, since the bumper will hit and turn you into the corner.