DRIVELINE CLUNK WHEN STOPPING (SPECIAL LUBRICANT)

Subject: DRIVELINE STOP CLUNK

Model and Year: 1988-91 C1 AND C2 TRUCKS AND 1991-92 CAPRICE WITH 3L80 AND 4L60 AUTOMATIC TRANSMISSION

THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NO. 91-242-7A, DATE MARCH 1991. THE 1991-92 CAPRICE HAS BEEN ADDED. ALL COPIES OF 91-242-7A SHOULD B DISCARDED.

Normal driveline tension build-up is released following vehicle braking on some 1988-91 C1 and C2 model (with single piece propshafts and automatic transmissions) and 1991-92 "B" Models as driveline clunk when stopping. The tension build-up is the result of the driveshaft splines binding on the transmission slip yoke. To eliminate stop clunk due to spline-yoke bind, the driveshaft splines should be lubricated with a special lubricant. This bulletin releases a new lubricant that has increased durability over the previously release lubricant.

NOTICE: This procedure should be applied to 1988-91 C1, C2 vehicles with automatic transmissions an one-piece propshafts only and 1991-92 B Models. When applied to other vehicles, possible transmission lube contamination could result.

SERVICE PROCEDURE:

1. Remove driveshaft.

2. Clean slip yoke and inside of driveshaft spline with solvent and clean cloth.

3. Apply grease (P/N 12345879) to slip yoke spline with a brush or swab, so as to completely cover the entire spline with a light coating of grease.

4. Reinstall driveshaft.

SERVICE PARTS INFORMATION

Part Number Description ----------- -------------------------------- 12345879 1lb. can of special lubricant (should service about 50 vehicles)

Parts are currently available from GMSPO.

WARRANTY INFORMATION

For vehicles repaired under warranty use:

Labor Operation: T7995 Labor Time: .4 hr

NOTE: Labor Operation is coded to base vehicle coverage in the warranty system.

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.