DRIVELINE STOP CLUNK SPECIAL LUBRICANT

SUBJECT: DRIVELINE STOP CLUNK (SPECIAL LUBRICANT)

VEHICLES AFFECTED: 1988-91 "C" TRUCKS WITH 4L60 AND 3L80 AUTOMATIC TRANSMISSION AND 1991-92 "B" MODELS

THIS BULLETIN SUPERSEDES AND REPLACES CORPORATE BULLETIN REFERENCE NUMBER 964101R." THIS BULLETIN IS BEING REVISED TO ADD 1991-92 'B" SEDANS AND WAGONS.

Normal driveline tension build-up is released following vehicle braking on some 1988-91 Cl and C2 models (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 released lubricant.

NOTICE: This procedure should be applied to 1988-91 Cl, C2 vehicles with automatic transmissions and 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 2.2 Kg (1 lb) can of special lubricant (should service about 50 vehicles)

For vehicles repaired under warranty use:

Labour Time: 0.4 hr

**BULLETIN REFERENCES:

Corporate Ref. 964101R

General Motors of Canada 90-4-101 and 91-4-105 Chevrolet Division 89-236-7A, 91-242-7A and 92-265-7A Buick Division 92-74L60-7 GMC Truck Division 89-T-98 and 91 -4A-77

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.