REAR TIRES CHIRP WHEN BRAKING INSTALL REVISED LININGS

SUBJECT: REAR TIRE CHIRP DURING BRAKING (INSTALL REVISED LININGS)

VEHICLES AFFECTED: 1990-92 C3, K3 WITH RPO JB8 BRAKES (9.000# - 12.000# GVW)

Owners of some 1990-92 C3, K3 trucks with JB8 Brakes (9,000# - 12,000# GVW) may experience rear tire chirp during certain brake applications. The condition is caused by a relatively high contamination sensitivity of the thermoid D-994-1 lining material.

This condition may be corrected by installing new rear brake shoes (P/N 15634849) that consist of a DM 9100 lining material that has demonstrated a reduced contamination sensitivity from the current lining. The DM 9100 facings can be identified by the "GM243EE" code printed on the edge. The rear brake drums must either be resurfaced or replaced for the new linings to be effective.

SERVICE PROCEDURE:

l. Raise the vehicle.

2. Remove the rear wheel/tire assemblies.

3. Remove the rear brake drum retainer clips and remove the brake drums.

4. Remove the actuator spring and the adjuster actuator.

5. Remove the hold down spring assemblies and pins.

6. Remove the lower return springs.

7. Remove the shoe and lining assemblies along with the upper return spring and the adjusting screw assembly.

8. Remove the upper return spring and the adjusting screw assembly from the shoes.

9. Remove the retaining ring, pin, spring washer and the parking brake lever.

10. Resurface the drums.

11. Install the park brake lever on the shoe with the spring washer, pin, and retaining ring.

12. Install the adjuster pin.

13. Install the upper return spring into the shoe web holes.

14. Install the adjusting screw assembly between the shoes.

15. Install the shoe and NEW DM-9100 lining assemblies (P/N 15634849), upper return spring and the adjusting screw assembly over the axle and behind the axle flange to the backing plate.

16. Install the lower return spring.

17. Install the brake shoe hold down pins and springs.

18. Install the adjuster actuator over the adjuster pin.

19. Install the actuator spring.

20. Install the brake drum.

21. Inspect and adjust the brakes.

22. Install the rear wheel/tire assemblies.

23. Lower the vehicle.

SERVICE PARTS INFORMATION

Part Number Description Application Quantity ----------- ----------- ----------- -------- 15634849 Primary and Secondary C/K 3 1 Brake Shoes Kit

WARRANTY INFORMATION:

For vehicles repaired under warranty use:

Labour Operation: H0257

Labour Time: 0.9 hrs.

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.