We performed extensive testing of rear upper control arm bushing materials during the development of our
Panhard Bar. When retaining the original four-link
suspension, the best compromise between resistance to
suspension bind, best control of axle position, best ride quality, and least potential damage to the chassis, is to retain rubber bushings in the rear
upper control arms. This is especially important when adding a
Panhard Bar. The compliance of a rubber-bushed upper control arm is required when a
Panhard bar is added to the Mustang four-link
suspension.