Chevrolet Silverado / GMC Sierra. Manual — part 1529

1. Using the J 42450-A , thoroughly clean any rust or corrosion from the mating surface of the

hub/axle flange. See Special Tools.

2. Using the J 41013 , thoroughly clean any rust or corrosion from the mating surface and

mounting surface of the brake rotor. See Special Tools.

3. Inspect the mating surfaces of the hub/axle flange and the rotor to ensure that there are no

foreign particles or debris remaining.

4. Mount the brake rotor to the brake lathe according to the lathe manufacturer's instructions,

ensuring that all mounting attachments and adapters are clean and free of debris.

5. Ensure that any vibration dampening attachments are securely in place.

6. With the brake lathe running, slowly bring in the cutting tools until they just contact the

brake rotor friction surfaces.

7. Observe the witness mark on the brake rotor. If the witness mark extends approximately

three-quarters or more of the way around the brake rotor friction surface on each side, the
brake rotor is properly mounted to the lathe.

8. If the witness mark does not extend three-quarters or more of the way around the brake

rotor, re-mount the rotor to the lathe.

9. Following the brake lathe manufacturer's instructions, refinish the brake rotor.

10. After each successive cut, inspect the brake rotor thickness. Refer to Brake Rotor

Scoring of the disc brake rotor surface in excess of the
maximum allowable specification

Disc brake rotors may need to be refinished as part of the
process for correcting brake rotor assembled lateral runout
(LRO) that exceeds the maximum allowable specification.

IMPORTANT: If the vehicle is equipped with cross-drilled rotors, use a lathe

with positive rake tooling. This setup requires less cutting
pressure, which will result in less vibration, and a better surface
finish. Also, use a vibration dampener when cutting. Otherwise,
refinish according to the following instructions.

IMPORTANT: Whenever the brake rotor has been separated from the

hub/axle flange, clean any rust or contaminants from the
hub/axle flange and the brake rotor mating surfaces. Failure
to do this may result in increased assembled lateral runout
(LRO) of the brake rotor, which could lead to brake pulsation.

2008 Chevrolet Silverado 1500

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

Thickness Measurement.

11. If at any time the brake rotor exceeds the minimum allowable thickness after refinish

specification, the brake rotor must be replaced.

12. After refinishing the brake rotor, use the following procedure in order to obtain the desired

non-directional finish:

1. Follow the brake lathe manufacturer's recommended speed setting for applying a non-

directional finish.

2. Using moderate pressure, apply the non-directional finish:

If the lathe is equipped with a non-directional finishing tool, apply the finish with
120-grit aluminum oxide sandpaper.

If the lathe is not equipped with a non-directional finishing tool, apply the finish
with a sanding block and 150-grit aluminum oxide sandpaper.

3. After applying a non-directional finish, clean each friction surface of the brake rotor

with denatured alcohol, or an equivalent approved brake cleaner.

13. Remove the brake rotor from the brake lathe.

14. Measure the assembled LRO of the brake rotor to ensure optimum performance of the disc

brakes. Refer to Brake Rotor Assembled Lateral Runout Measurement.

15. If the brake rotor assembled LRO measurement exceeds the specification, bring the LRO to

within specifications. Refer to Brake Rotor Assembled Lateral Runout Correction.

DESCRIPTION AND OPERATION

DISC BRAKE SYSTEM DESCRIPTION AND OPERATION

System Component Description

The disc brake system consists of the following components:

Disc Brake Pads

Applies mechanical output force from the hydraulic brake calipers to friction surfaces of
brake rotors.

Disc Brake Rotors

Uses mechanical output force applied to friction surfaces from the disc brake pads to slow
speed of tire and wheel assembly rotation.

Disc Brake Pad Hardware

2008 Chevrolet Silverado 1500

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

Secures disc brake pads firmly in proper relationship to the hydraulic brake calipers.
Enables a sliding motion of brake pads when mechanical output force is applied.

Disc Brake Caliper Hardware

Provides mounting for hydraulic brake caliper and secures the caliper firmly in proper
relationship to caliper bracket. Enables a sliding motion of the brake caliper to the brake
pads when mechanical output force is applied.

System Operation

Mechanical output force is applied from the hydraulic brake caliper pistons to the inner brake
pads. As the pistons press the inner brake pads outward, the caliper housings draw the outer brake
pads inward. This allows the output force to be equally distributed. The brake pads apply the
output force to the friction surfaces on both sides of the brake rotors, which slows the rotation of
the tire and wheel assemblies. The correct function of both the brake pad and brake caliper
hardware is essential for even distribution of braking force.

SPECIAL TOOLS AND EQUIPMENT

SPECIAL TOOLS

Illustration

Tool Number/Description

J 8001

Dial Indicator Set

J 39544-KIT

Torque-Limiting Socket Set

2008 Chevrolet Silverado 1500

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