GM Service Manual Online
For 1990-2009 cars only

Replace the rear axle if any damage exists which affects the misalignment or the structural integrity of the rear axle housing. Do not weld or straighten the rear axle housing. This process may affect the rear axle housing metallurgy, and cause the rear axle housing to fail completely when under load.

  1. Block the front wheels.
  2. Raise and support the rear axle housing.
  3. Inspect the rear wheel bearing adjustment and the rear wheel mounting.
  4. Place a chalk mark in the following locations:
  5. • On the top of the outer side wall of both outside rear tires
    • At the bottom of the rear tires near the ground (180 degrees from the first marks)
  6. Measure across the rear tires at the chalk mark using a toe-in gage. Record the reading.
  7. Rotate the rear wheels in order to position the chalk marks at the top of the rear wheels.
  8. Measure across the rear tires at the chalk mark using a toe-in gage. Record the reading.
  9. Compare the top measurement with the bottom measurement. The measurements should be the same within 3.2 mm (0.125 in).
  10. •  If the top measurement is more than 3.2 mm (0.125 in) larger than the bottom measurement, the rear axle is bent at the ends.
    •  If the top measurement is more than 3.2 mm (0.125 in) smaller than the bottom measurement, the rear axle housing has sagged.
  11. Turn the rear wheels so that the chalk marks on both rear wheels are parallel to the ground (level with the rear axle housing) and facing toward the rear of the vehicle.
  12. Measure across the rear tires at the chalk mark using a toe-in gage. Record the reading.
  13. Turn the rear wheels half way around so that the chalk marks are positioned parallel to the ground (level with the rear axle housing) and facing toward the front of the vehicle.
  14. Measure across the rear tires at the chalk mark using the toe-in gage. Record the reading.
  15. Compare the front and the rear readings. They should be the same within 3.2 mm (0.125 in).
  16. •  If the rear measurement is more than 3.2 mm (0.125 in) greater than the front measurement, the rear axle housing is bent forward.
    • If the rear measurement is 3.2 mm (0.125 in) less than the front measurement, the rear axle housing is bent to the rear.