GM Service Manual Online
For 1990-2009 cars only

Removal Procedure

Important: Do not wash the proportioning valve in any cleaning solution. The internal components are prelubricated with a special grease.

  1. Remove the ABS hydraulic modulator/master cylinder. Refer to Antilock Brake System.
  2. Remove the master cylinder reservoir. Refer to Master Cylinder Reservoir Replacement .

  3. Object Number: 176833  Size: SH
  4. Remove the proportioning valve caps (1).
  5. Remove the O-rings (5).
  6. Remove the springs (2).
  7. Remove the proportioning valve pistons (3). Carefully use needle nose pliers. Do not damage the piston stems.
  8. Remove the proportioning valve seals (4) from the pistons (3).
  9. Inspect the proportioning valve pistons (3) for corrosion and deformation. Replace the valve pistons (3) if necessary.
  10. Clean all of the parts in clean, denatured alcohol.
  11. Dry the parts. Use non-lubricated compressed air.

Installation Procedure


    Object Number: 176833  Size: SH
  1. Lubricate the following parts. Use the silicone grease that is supplied in the repair kit:
  2. • New O-rings (5)
    • New proportioning valve seals (4)
    • Proportioning valve piston stems
  3. Install new seals (4) on the proportioning valve pistons (3). Ensure that the seal lips face upward toward the cap.
  4. Install the proportioning valve pistons (3) and the seals (4) in the master cylinder body.
  5. Install the springs (2) in the master cylinder body.
  6. Install new O-rings (5) in the grooves in the proportioning valve caps (1).
  7. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  8. Install the proportioning valve caps (1) in the master cylinder body.
  9. Tighten
    Tighten the proportioning valve caps (1) to 27 N·m (20 lb ft).

  10. Install the master cylinder reservoir. Refer to Master Cylinder Reservoir Replacement .
  11. Install the ABS hydraulic modulator/master cylinder. Refer to Antilock Brake System.