GM Service Manual Online
For 1990-2009 cars only

Cause

Correction

Inspect for the proper gear oil levels prior to performing system diagnosis. Refer to Axle Lubricant Change .

A light "clunk" type noise during a downshift is to be considered a normal condition.

Loose propeller shaft mounting bolts

Tighten the bolts as required. Refer to Propeller Shaft Replacement .

Worn propeller shaft constant velocity joints

Replace the propeller shaft assembly. Refer to Propeller Shaft Replacement .

Worn axle shaft constant velocity joints

Replace the constant velocity joints as required.

Worn, loose, or missing differential mounts

Repair or replace the differential mounts as required.

Loose torque tube bracket or a damaged bracket bushing

Tighten the bracket bolts or replace the bracket as required.

Worn bearing in the torque tube assembly

Replace the torque tube assembly.

Bearing noise within the differential assembly

A "grinding" or "roar" type noise will increase or decrease relative to the vehicle speed.

  1. Check for the proper fluid level. Fill as required.
  2. If the noise continues, replace unit as required.

Gear set "whine" noise within the differential assembly

A "whine" type noise will increase or decrease relative to the vehicle speed, approximately 80-97 km/h (50-60 mph).

  1. Check for the proper fluid level. Fill as required.
  2. Replace unit as required.