- Remove the master cylinder. Refer to Master Cylinder Replacement .
- Remove the master cylinder reservoir. Refer to Master Cylinder Reservoir Replacement .
- Clamp the master cylinder into vise by one of the mounting ears (15).
- Remove the retainer (8) while depressing the primary piston assembly (9)
- Plug the primary outlet port (closest to the rear) of the master cylinder.
- Apply low pressure non-lubricated compressed air into the secondary outlet port (at the front end) of the cylinder.
- Remove the following parts.
- Inspect the master cylinder bore for scoring or corrosion. If any damage is present replace the master cylinder assembly.
- Clean all parts with denatured alcohol.
- Dry with non-lubricated compressed air.
- Lubricate all parts with new Delco® Supreme ll Brake fluid, GM P/N 12377967, or equivalent DOT 3 brake fluid.
- Install the secondary spring and piston assembly into the bore (14,11,12,13,10).
- Install the primary piston assembly (9) and depress enough to install the retainer (8).
- Install the master cylinder reservoir. Refer to Master Cylinder Reservoir Replacement .
- Bench bleed the master cylinder. Refer to Master Cylinder Bench Bleeding .
- Install the master cylinder. Refer to Master Cylinder Replacement .
Notice: Do not clamp on the master cylinder body. Doing so may damage the master cylinder.
Notice: Use care not to damage the piston bore or retainer groove during primary piston retainer ring removal.
Caution: Wear safety glasses when using compressed air in order to prevent eye injury.
Caution: If air pressure is used to remove the secondary piston, place the open end of the cylinder bore approximately 25 mm (1 in) from a padded workbench or other surface to catch the piston when it comes out of the bore. Apply low air pressure very carefully to ease the piston out of the bore. Never point the open end of the bore at anyone when applying air pressure. The piston may come out of the bore with considerable force and cause personal injury.
| 7.1. | Primary piston assembly (9). |
| 7.2. | Primary seal (10). |
| 7.3. | Secondary piston (13). |
| 7.4. | Secondary seal (12). |
| 7.5. | Spring retainer (11) and spring (14). |
Notice: Do not hone the master cylinder bore. When the brake master cylinder is overhauled, it is recommended that the cylinder body be replaced rather than CLEANED UP by honing the bore. The master cylinder has a hard, highly polished BEARINGIZED surface, which is produced by diamond boring followed by ball or roller burnishing under heavy pressure. Honing will destroy this hard smooth surface and cause rapid wear of the rubber cups.
