GM Service Manual Online
For 1990-2009 cars only

Adjustment Procedure

If rear tire wear indicates that the rear axle housing may be bent, or that the rear springs may be dislocated, check the alignment.

Important: Do not straighten the axle housing in order to correct an alignment problem. If the axle housing is not straight, the axle assembly must be replaced.

  1. Back the vehicle squarely onto an alignment machine.
  2. Compensate for wheel runout the same way you check front wheel toe-in.
  3. Check the camber reading. This should be 0.03 degrees negative-0.05 degrees positive.
  4. Check the amount of toe-in. This should be 0-0.05 degrees or 0-1.58 mm (0-1/16 in).
  5. • When the vehicle is backed onto an alignment machine, the actual toe-out will read on the scale as toe-in. If toe-out is checked with a tram gauge, disregard this step.
    • If a tram gauge is used for checking toe-out, perform steps 1 and 2 to check camber.

You can not align the rear wheels by regular means. Replace bent or damaged axle housing and springs. The frame often is not straight. You can straighten the frame using frame straightening equipment, or by relocating the spring to the axle without removing the axle housing from the vehicle. In this way you can determine when the axle and spring assemblies are within the correct limits during the straightening operation.

If the frame and the springs are within specification, then the rear axle assembly is not straight, and you must replace the rear axle.