Disassembly Procedure

Fig 1: Master Cylinder Components

Courtesy of GENERAL MOTORS CORP.

CAUTION: Refer to Brake Fluid Irritant Caution in Cautions and Notices.

CAUTION: Refer to Brake Fluid Caution in Cautions and Notices.

NOTE: Refer to Filling the Master Cylinder Notice in Cautions and Notices.

NOTE: 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.

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

Fig 2: Pushing Master Cylinder Piston

Courtesy of GENERAL MOTORS CORP.

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

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

Fig 3: Removing Master Cylinder Snap Ring

Courtesy of GENERAL MOTORS CORP.

Push the piston into the master cylinder and remove the snap ring.

Fig 4: Master Cylinder Components

Courtesy of GENERAL MOTORS CORP.

Remove the following components from the master cylinder:
1. The plate (7)
2. The cylinder cup (8)
3. The O-ring (9)
4. The piston guide (10)
5. The primary piston and spring (11)
Remove the master cylinder from the vise.

Fig 5: Tapping Cylinder Flange

Courtesy of GENERAL MOTORS CORP.

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.
Tap the cylinder flange against the blocks in order to remove the secondary piston and spring.
Wash the disassembled parts with clean brake fluid.

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

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