GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2006 🢒 Vibe - FWD 🢒 Brakes 🢒 Hydraulic Brakes 🢒 Master Cylinder Overhaul

Disassembly Procedure

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

    Caution: Refer to Brake Fluid Caution in the Preface section.

    Notice: Refer to Filling the Master Cylinder Notice in the Preface section.


    Object Number: 830248 Size: SH

    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.

  1. Remove the master cylinder (6) from the vehicle. Refer to Master Cylinder Replacement .
  2. Remove the 2 grommets (4, 7).
  3. Remove the O-ring from the master cylinder bore.
  4. If the vehicle has the stability system, complete the following steps:
    5. 4.1. Place a rag on a table.
    4.2. Hold the master cylinder with the reservoir ports down over the rag.
    4.3. Push in the piston and allow the piston stop pin to fall out.

    Object Number: 815504 Size: SH

    Notice: Do not clamp on the master cylinder body. Doing so may damage the master cylinder.

  5. Place the master cylinder in a vise.
  6. If the vehicle does NOT have the stability system, push in the piston and remove the piston stopper bolt and the gasket.

    7. Object Number: 815506 Size: SH
  7. Push the piston into the master cylinder and remove the snap ring.

    8. Object Number: 830251 Size: SH
  8. Remove the following components from the master cylinder:
    9. 8.1. The plate (7)
    8.2. The cylinder cup (8)
    8.3. The O-ring (9)
    8.4. The piston guide (10)
    8.5. The primary piston and spring (11)
  9. Remove the master cylinder from the vise.

    10. Object Number: 239139 Size: SH
  10. Place a rag and 2 wooden blocks on a table. Allow at least 100 mm (3.94 in) between the top of the rag and the top of the blocks (1) for the secondary piston.
  11. Tap the cylinder flange against the blocks in order to remove the secondary piston and spring.
  12. Wash the disassembled parts with clean brake fluid.

    13. Notice: Do not use lubricated compressed air on brake parts as damage to rubber components may result.

  13. Dry the parts with compressed air.
  14. Inspect the parts for wear or damage. Replace any worn or damaged parts.
  15. Inspect the master cylinder bore for scoring or corrosion. Replace a damaged master cylinder.

Assembly Procedure

    Object Number: 830251 Size: SH
  1. Wash the new internal parts with clean brake fluid.
  2. Place the master cylinder in a vise.
  3. Install the following components into the master cylinder:
    4. 3.1. The secondary piston and spring (12)
    3.2. The primary piston and spring (11)
    3.3. The piston guide (10)
    3.4. The O-ring (9)
    3.5. The cylinder cup (8)
    3.6. The plate (7)
    3.7. The snap ring (6)
    3.8. The O-ring (5)
  4. If the vehicle has the stability system, push in the piston and install the piston stop pin.

    5. Notice: Refer to Fastener Notice in the Preface section.

  5. If the vehicle does NOT have the stability system, push in the piston and install the gasket (14) and the piston stopper bolt (13).

    6. Tighten
    Tighten the bolt to 10 N·m (88.5 lb in).

  6. Wash the grommets in brake fluid.
  7. Install the 2 grommets (2, 3).
  8. Remove the master cylinder from the vise.
  9. Install the master cylinder to the vehicle. Refer to Master Cylinder Replacement .