Chevrolet Silverado / GMC Sierra. Service manual — part 1566

maximum allowable measurement, the drum requires replacement.

BRAKE DRUM SURFACE AND WEAR INSPECTION

Tools Required

J 8001 Dial Indicator Set, or equivalent

Inspection

1. With the brake drum removed, clean the braking (friction) surface of the brake drum with

denatured alcohol or an equivalent approved brake cleaner.

2. Inspect the braking surface of the brake drum for the following braking surface conditions:

Heavy rust and/or pitting-Light surface rust can be removed with an abrasive disc.
Heavy surface rust and/or pitting must be removed by refinishing the drum.

Cracks and/or heat spots

Excessive blueing discoloration

Missing balance weights

3. If the braking surface of the brake drum exhibits 1 or more of the braking surface

conditions, the drum requires refinishing or replacement.

CAUTION: Refer to Brake Dust Caution .

2008 Chevrolet Silverado 1500

2008 BRAKES Drum Brakes - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Fig. 2: Measuring Brake Drum
Courtesy of GENERAL MOTORS CORP.

4. Using a brake drum micrometer calibrated in thousands of an inch, measure and record any

grooves present on the drum braking surface.

Ensure that the measurements are only taken within the brake shoe lining contact area.

5. Compare the groove, scoring, depth recorded to the following specification:

Specification: Brake drum maximum allowable scoring 1.5 mm (0.06 in).

6. If the brake drum scoring depth exceeds the specification, or if an excessive amount of

scoring is present, the drum requires refinishing or replacement.

7. Mount the brake drum on a brake lathe.

8. Mount a dial indicator, J 8001 or equivalent, and position the indicator button so it contacts

the braking surface of the brake drum at a 90 degree angle, approximately 19 mm (0.75 in)
from the drum's outer edge.

9. Measure and record the radial runout of the brake drum.

2008 Chevrolet Silverado 1500

2008 BRAKES Drum Brakes - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

1. Rotate the drum until the lowest reading is displayed on the indicator dial, then zero

the dial.

2. Rotate the drum until the highest reading is displayed on the dial.

10. Compare the radial runout of the brake drum to the following specification:

Specification: Brake drum maximum allowable radial runout 0.06 mm (0.0024 in).

11. If the brake drum radial runout exceeds the specification, the drum requires refinishing or

replacement.

DRUM BRAKE ADJUSTING HARDWARE INSPECTION

1. Inspect the drum brake adjusting hardware for the following:

Excessive corrosion

Damaged or broken adjuster spring

Damaged or broken adjuster lever

Damaged or broken adjuster star wheel and or adjuster thread

2. If components are found to be damaged, replace them.

REPAIR INSTRUCTIONS

BRAKE SHOE INSPECTION

Inspect the linings every 9 650 km (6,000 mi) and any time the wheels are removed (tire rotation,
etc.). Inspect the lining for wear by removing the plug and using the inspection hole. Replace the
shoe and lining assemblies when the thickness of any lining is worn within 0.72 mm (0.030 in) of
the shoe. Replace riveted shoe and lining assemblies when the lining is worn to within 0.76 mm
(0.030 in) of any rivet head. Always replace shoe and lining assemblies as a complete axle set.

BRAKE DRUM REPLACEMENT

2008 Chevrolet Silverado 1500

2008 BRAKES Drum Brakes - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Fig. 3: View Of Brake Drum And Retainers
Courtesy of GENERAL MOTORS CORP.

Callout

Component Name

Preliminary Procedures

1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .

2. Remove the tire and wheel assembly. Refer to Tire and Wheel Removal and

Installation .

CAUTION:

Refer to Brake Dust Caution .

1

Brake Drum Retainer (Qty: 2)

2

Brake Drum

Procedure

1. If the brake drum will not slide over the brake shoes, retract the brake

shoe adjuster. Refer to Drum Brake Adjustment.

2. Using the J 42450-A , clean the drum mating surface of the rear axle

2008 Chevrolet Silverado 1500

2008 BRAKES Drum Brakes - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado