Master Cylinder Overhaul

Master Cylinder:

Note: Reservoir cap and diaphragm can be inspected and/or serviced without removing the master cylinder from the vehicle.

Disassemble
1. Master cylinder completely from vehicle.
2. Reservoir cap (7) and diaphragm (8).

^ Wipe reservoir cap clean before removing.
^ If master cylinder is to be completely removed and overhauled, empty fluid from reservoir.

Inspect
^ Reservoir cap (7) and diaphragm (8) for:
- Cuts
- Cracks
- Nicks
- Deformation
^ Replace damaged parts.

3. Fluid level sensor (1) and proportioner valve assemblies (2 through 6), if installed.
4. Retainer (13) while depressing primary piston assembly (14).

^ Take care not to damage the piston, bore, or retainer groove.

5. Apply low pressure unlubricated compressed air into upper outlet port at blind end of bore (all other outlet ports plugged) to remove:

^ Primary piston assembly (14).
^ Secondary piston (18).
^ Spring (19).
^ Spring retainer (16).

6. From secondary piston (18):

^ Seals (15 and 17).
^ Spring retainer (16).

Inspect
^ Master cylinder bore for scoring or corrosion. If noted, replace master cylinder. No abrasives should be used in bore.

Clean
^ All parts in clean, denatured alcohol.
- Dry with unlubricated compressed air.

Assemble
1. Lubricated seals (15 and 17) and spring retainer (16) onto secondary piston (18).
2. Spring (19) and secondary piston assembly through 18) into cylinder bore.

^ To ease reassembly, lubricate with clean brake fluid.

3. Lubricated primary piston assembly (14) into cylinder bore.
4. Retainer (13) while depressing primary piston assembly (14).
5. Proportioner valve assemblies (2 through 6).
6. Fluid level sensor (1).
7. Diaphragm (8) into reservoir cap (7) and install on reservoir (10).
8. Master cylinder to vehicle.