Brake Shoe: Service and Repair

NOTE: GM replacement brake lining material is recommended for this vehicle to maintain the balance between front and rear brake performance. GM replacement brake parts have been carefully selected to provide the proper brake balance for the purposes of stopping distance and control over the full range of operating conditions. Installation of front or rear brake lining material with performance characteristics different from the recommended GM replacement parts can change the intended brake balance of this vehicle.

Duo-Servo Drum Brake Components:

Remove or Disconnect
1. Raise vehicle and support it with safety stands.
2. Mark relationship of wheel to hub.
3. Tire and wheel.
4. Mark relationship of drum to axle.
5. Drum.
6. Return springs (9 and 10).
7. Shoe guide (5).
8. Hold down springs (11).
9. Hold down pins (1).
10. Actuator lever (7) and lever pivot (12).
11. Lever return spring (13).
12. Actuator link (8).
13. Parking brake strut (6) and strut spring (14).
14. Parking brake lever (3).
15. Shoes (17 and 4).
16. Adjusting screw assembly (15).
17. Adjusting screw spring (16).

- Inspect
^ All parts for discoloration due to heat or stress. Replace as needed.
^ All parts for signs of wear. Replace as needed.
^ Wheel cylinder for signs of leakage. If any are found, refer to Wheel Cylinder, Service and Repair. Service and Repair
^ Brake drum for scoring and machining tolerance. Refer to Brake Drum Refinishing. Refinishing and Balance

Install or Connect
1. Lubricate shoe pads and adjusting screw threads with a thin coat of white lithium grease or equivalent.
2. Adjusting screw assembly (15) and adjusting screw spring (16) to both shoes (17 and 4).

NOTE: The coils of the adjusting screw spring must not touch the adjusting screw.

NOTE:Do not interchange right and left adjusting screws.

3. Shoe assembly to the backing plate.
4. Parking brake lever (3).
5. Strut spring (14) onto the parking brake strut (6).
6. Parking brake strut (6).
7. Actuator lever (7) and lever pivot (12).
8. Actuator link (8).
9. Lever return spring (13).
10. Hold down pins (1).
11. Hold down springs (11).
12. Shoe guide (5).
13. Return springs (9 and 10).
14. Drum.

NOTE: Align the marks made during disassembly.

15. Tire and wheel.

NOTE: Align the marks made during disassembly.

16. Adjust brakes.
A. Remove the knockout area in the backing plate.
B. Turn the adjusting screws until the wheels can just be turned by hand.
^ The brake drag should be equal at both wheels.
C. Back off the adjusting screw 24 notches.
^ Important brakes should have no drag after the screw has been backed off about 12 notches. If a heavy drag is present, refer to Parking Brake System. Adjustments
D. Install an adjusting hole cover in the brake backing plate.
E. Check the parking brake adjustment. Refer to Parking Brake System. Adjustments
17. Lower the vehicle.