REAR AXLE WHINE NOISE (REPLACE AXLE SHAFT)

Subject: REAR AXLE WHINE NOISE

Model and Year: 1990-1993 M/L VANS

THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NO. 91-460-4B DATED DECEMBER 1991. THE 1992 AND 1993 MODEL YEARS HAVE BEEN ADDED. ALL COPIES OF 91-460-4B SHOULD BE DISCARDED.

Owners of some 1990-1993 M/L vans may comment on rear axle whine. The whine may be caused by axles which were manufactured with grind chatter marks on the bearing ride surfaces of the rear axle shafts. The grind chatter will cause a "whine" noise which is noticeable during both drive and coast over the entire speed range. The bearing ride diameter is correct in all cases. The grind chatter marks are visible as longitudinal lines in the bearing ride surface.

SERVICE PROCEDURE:

Grind chatter can only be recognized in the bearing ride area by doing the following:

1. Clean/polish bearing ride area without introducing scratches.

2. Hold axle shaft horizontally under direct light.

3. Sight along horizontal center line of the shaft.

4. Chatter will appear as a systematic pattern of imperfections going all the way around the circumference of the bearing ride.

5. If an axle fits the above criteria, replace the suspect axle shaft (P/N 26015257 LH or 26015258 RH) using the procedures described in the M/L Service Manual section 4Bl.

SERVICE PARTS INFORMATION: Part Number Description ------------------------- ----------- ----------- 26015257 Axle Shaft (LH) 26015258 Axle Shaft (RH)

Parts are currently available from GMSPO.

WARRANTY INFORMATION:

For vehicles repaired under warranty use:

Labor Operation Description --------------- ----------- F1530 Axle Shaft Replace (RH) F1531 Axle Shaft Replace (LH)

Use applicable Labor Time Guide for labor hours.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.