Drum Brake Adjustment

Special Tools 

CH-21177-A  Drum to Brake Shoe Clearance Gauge

For equivalent regional tools, refer to Special Tools 

1. Ensure the park brake lever is in the fully released position.
   WARNING: Refer to Brake Dust Warning .
2. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle
3. Remove the tire and wheel assembly. Refer to Tire and Wheel Removal and Installation .
4. Remove the brake drum. Refer to Brake Drum Replacement .
5. Position the CH-21177-A  gauge to the widest point of the brake drum inside diameter.
   Fig 1: Measuring Inside Brake Drum Diameter

   Courtesy of GENERAL MOTORS COMPANY
6. Firmly hand tighten the set screw on the CH-21177-A  gauge.
7. Remove the CH-21177-A  gauge from the brake drum and position it over the corresponding brake shoe assembly at its widest point.
   Fig 2: Positioning J 21177-A Over Brake Shoe Assembly

   Courtesy of GENERAL MOTORS COMPANY
8. While holding the CH-21177-A  gauge in position, insert a proper feeler gauge between one side of the CH-21177-A  gauge and the corresponding brake shoe lining.
9. Rotate the brake shoe adjuster screw until the brake shoe linings contact the CH-21177-A  gauge and the feeler gauge.

   Specification 

   Brake shoe lining-to-drum clearance: 0.4-0.9 mm (0.016-0.035 in)

10. Repeat the above steps for the opposite brake drum and brake shoe assembly.
11. Install the brake drum. Refer to Brake Drum Replacement .
12. Install the tire and wheel assembly. Refer to Tire and Wheel Removal and Installation
13. Lower vehicle.
14. Apply the brake pedal at least 10 times. Verify the clicking sound of the adjuster assembly is not audible from either brake drum.
15. Adjust the park brake. Refer to Parking Brake Adjustment .
16. Lower the vehicle.