Check this out, it may help you. Place your chassis on a flat surface and push down on the chassis while checking the end play in the axle shaft. If at any point in the suspension travel the end play is gone, adjust the width of the front, or rear, track until there is some clearance. Since I have adjusted mine, I haven't broken any cups or shafts. When that truck hits the ground and the shafts bottom out, something has to give. If you modify the cups, then the shaft fails or the pivot balls are forced out of the control arms. On the other hand, the shocks and springs must do their job and absorb the energy of the drop. . . .