GM Service Manual Online
For 1990-2009 cars only

Master Cylinder Overhaul RHD

The master cylinder overhaul in this vehicle is not serviceable.

If the master cylinder is defective, you must replace the master cylinder assembly.

Master Cylinder Overhaul LHD

Disassembly Procedure


    Object Number: 1265686  Size: SH
  1. Remove the master cylinder. Refer to Master Cylinder Replacement .
  2. Notice: Do not clamp on the master cylinder body. Doing so may damage the master cylinder.

  3. Remove the retaining bolt and the seal from the cylinder.
  4. Important: When removing the retaining ring, avoid damaging the piston or the cylinder wall.

  5. Remove and discard the retaining ring from the cylinder body.

  6. Object Number: 1265687  Size: SH
  7. Remove the primary piston assembly.
  8. Carefully remove the secondary piston assembly, including the spring, from the master cylinder bore.

Installation Procedure


    Object Number: 1265687  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. Lubricate the master cylinder bore with new brake fluid.
  2. Install the secondary piston assembly, including the spring to the master cylinder bore.
  3. Install the primary piston assembly.

  4. Object Number: 1265686  Size: SH

    Important: Use care when installing the retaining ring.

  5. Install a NEW retaining ring to the cylinder body.
  6. Install the retaining bolt and seal to the cylinder.
  7. Install the master cylinder.
  8. Add the new brake fluid.
  9. Bleed the brake system. Refer to Hydraulic Brake System Bleeding .