Volt

Rear Brake Calliper Overhaul

Warning: Refer to Brake Fluid Irritant Warning in the Preface section.

1. Remove the rear brake calliper from vehicle. Refer to Rear Brake Calliper Replacement .
2. Drain the brake fluid from the calliper assembly.




Note: If the brake calliper was leaking brake fluid from the REAR of the calliper past the integral hand brake actuator shaft seal, replace the brake calliper assembly. The hand brake integral mechanism contains a non-serviceable seal which may be allowing brake fluid to leak past it and into the non-serviceable integral hand brake mechanism.

3. Firmly clamp the calliper assembly (1) in a soft-jawed vice.
4. Using a small wooden or plastic tool, carefully remove the brake calliper piston dust boot seal retaining ring from the groove in the calliper seal counterbore.
5. Carefully rotate the calliper piston (2) counter-clockwise and remove the calliper piston from the brake calliper housing.
6. Remove the brake calliper piston dust boot seal (3) from the brake calliper housing.
7. Using a small wooden or plastic tool, remove the piston seal from the calliper bore and discard the piston seal.
8. Inspect the operation of the integral hand brake mechanism: Rotate the hand brake lever back and forth while observing the movement of the hand brake mechanism actuator assembly in the calliper bore.

Note: The hand brake lever, lever return spring and actuator shaft seal are not serviceable components of the integral hand brake mechanism. Do not disassemble the integral hand brake mechanism.

9. If the integral hand brake mechanism was not operating properly, binding or seized, replace the brake calliper assembly.

Note: Do not use abrasives to clean the brake calliper piston.

10. If cracks, scoring, pitting, and/or excessive corrosion are present in the calliper bore, replace the calliper assembly.
11. If light corrosion is present in the calliper bore, attempt to remove the imperfection with a fine emery paper. If the imperfection cannot be removed, replace the calliper assembly.
12. Clean the brake calliper piston bore and seal counterbore, the calliper piston, and the calliper sleeves with denatured alcohol, or equivalent.
13. Dry the calliper piston bore and counterbore, the piston, and the sleeves with non-lubricated, filtered compressed air.
14. Inspect the calliper piston for cracks, scoring, damage to the plating, and/or damage to the integral adjusting mechanism. Replace the calliper piston if any of these conditions exist.
15. Inspect the calliper mounting holes for cracks, scoring, pitting, and/or excessive corrosion. Replace the calliper assembly if any of these conditions exist.

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 .
2. Install the new piston seal into the calliper bore.
3. Ensure the piston seal is seated squarely into the groove in the calliper bore and is not twisted.



4. Install the new dust boot seal (1) onto the calliper piston (2).



5. With the calliper housing (1) firmly secured in a soft-jawed vise, insert the calliper piston (2) into the calliper housing.
6. Using a spanner type wrench, rotate the piston clockwise while pushing the piston into the calliper housing bore.
7. When the calliper piston is fully seated into the calliper housing, align the notches in the calliper piston face to the pins on the inboard brake pad.
8. Fully seat the piston dust boot seal (3) in the calliper counterbore.
9. Install the piston dust boot seal retaining ring to the groove in the calliper counterbore.
10. Install the brake calliper to the vehicle. Refer to Rear Brake Calliper Replacement .

Inspect the brake calliper for brake fluid leaks while performing the hydraulic brake system bleeding procedure after the calliper has been installed to the vehicle. If the brake calliper leaks brake fluid from the FRONT of the calliper past the piston dust boot seal, replace the calliper 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 calliper piston.