Squaring length-adjustable rear lower control arms.
Imagine looking down on the rear axle in plain view using your Superman X-ray vision. If the axle is cocked sideways relative to the chassis, the car will dog-track down the highway and exhibit different turning characteristics left-to-right.This relationship is adjustable if you have adjustable-length control arms. Simple tape measurements will tell the tale and turning the adjusters will move the axle.
Set pinion angle.
By design, torque arms set the rear pinion angle. This is fine-tuned with the Maximum Motorsports torque arm with shims placed between the front of the differential and the torque-arm mount. The pinion angle is measured using a straightedge and protractor, both at the differential flange and at the transmission. The straightedge is necessary only to transfer the measuring surface away from the crowded torque-arm-driveshaft-differential interface. In the photo, the point where the shims go is just behind the measuring device.