Rear Brake Caliper Overhaul
Rear Brake Caliper Overhaul
Disassembly
Warning:
Refer to Brake Fluid Irritant Warning Brake Fluid Irritant Warning.
1. Remove the rear brake caliper from vehicle. Refer to Rear Brake Caliper Replacement Rear Brake Caliper Replacement.
2. Drain the brake fluid from the caliper assembly.
Note:
If the brake caliper was leaking brake fluid from the REAR of the caliper past the integral park brake actuator shaft seal, replace the brake caliper assembly. The park brake integral mechanism contains a non-serviceable seal which may be allowing brake fluid to leak past it and into the non-serviceable integral park brake mechanism.
3. Firmly clamp the caliper assembly (1) in a soft-jawed vice.
4. Using a small wooden or plastic tool, carefully remove the brake caliper piston dust boot seal retaining ring from the groove in the caliper seal counterbore.
5. Carefully rotate the caliper piston (2) counter-clockwise and remove the caliper piston from the brake caliper housing.
6. Remove the brake caliper piston dust boot seal (3) from the brake caliper housing.
7. Using a small wooden or plastic tool, remove the piston seal from the caliper bore and discard the piston seal.
8. Inspect the operation of the integral park brake mechanism: Rotate the park brake lever back and forth while observing the movement of the park brake mechanism actuator assembly in the caliper bore.
Note:
The park brake lever, lever return spring and actuator shaft seal are not serviceable components of the integral park brake mechanism. Do not disassemble the integral park brake mechanism.
9. If the integral park brake mechanism was not operating properly, binding or seized, replace the brake caliper assembly.
Note:
Do not use abrasives to clean the brake caliper piston.
10. If cracks, scoring, pitting, and/or excessive corrosion are present in the caliper bore, replace the caliper assembly.
11. If light corrosion is present in the caliper bore, attempt to remove the imperfection with a fine emery paper. If the imperfection cannot be removed, replace the caliper assembly.
12. Clean the brake caliper piston bore and seal counterbore, the caliper piston, and the caliper sleeves with denatured alcohol, or equivalent.
13. Dry the caliper piston bore and counterbore, the piston, and the sleeves with non-lubricated, filtered compressed air.
14. Inspect the caliper piston for cracks, scoring, damage to the plating, and/or damage to the integral adjusting mechanism. Replace the caliper piston if any of these conditions exist.
15. Inspect the caliper mounting holes for cracks, scoring, pitting, and/or excessive corrosion. Replace the caliper assembly if any of these conditions exist.
Assembly
1. Lubricate the new piston seal with GM approved brake fluid from a clean, sealed brake fluid container. Refer to Adhesives, Fluids, Lubricants, and Sealers Fluid Type Specifications.
2. Install the new piston seal into the caliper bore.
3. Ensure the piston seal is seated squarely into the groove in the caliper bore and is not twisted.
4. Install the new dust boot seal (1) onto the caliper piston (2).
5. With the caliper housing (1) firmly secured in a soft-jawed vise, insert the caliper piston (2) into the caliper housing.
6. Using a spanner type wrench, rotate the piston clockwise while pushing the piston into the caliper housing bore.
7. When the caliper piston is fully seated into the caliper housing, align the notches in the caliper piston face to the pins on the inboard brake pad.
8. Fully seat the piston dust boot seal (3) in the caliper counterbore.
9. Install the piston dust boot seal retaining ring to the groove in the caliper counterbore.
10. Install the brake caliper to the vehicle. Refer to Rear Brake Caliper Replacement Rear Brake Caliper Replacement.
Inspect the brake caliper for brake fluid leaks while performing the hydraulic brake system bleeding procedure after the caliper has been installed to the vehicle. If the brake caliper leaks brake fluid from the FRONT of the caliper past the piston dust boot seal, replace the caliper piston assembly. The piston integral adjustment mechanism contains a non-serviceable seal which may be allowing brake fluid to leak past it through a bleed hole near the end of the caliper piston.