66-67 Dodge Charger Source Guide

Basically our cars were never designed for radial tires. There isn't enough caster adjustment. Caster is like a bicycle front wheel. The more a fork is tilted the easier it is to ride without hands because the caster keeps the bike in a straight line.

For radial tires our cars need about 2 3/4 to 3 degrees of caster. The geometry of the front end components only allow about 1 3/4 max. So to overcome this problem and allow more caster Moog and TRW came up with an upper control arm bushing (the one the adjusting bolt goes through) that is offset. The solution is to install these bushings with the offset in at the front and out at the rear. This will give up up to 2 degrees more caster which will solve your problem.

The October 2005 issue of Mopar Action had an article on this subject. They recommend the following for a typical street car.

You want as much positive caster as you can get with radials.