GENERAL INFORMATION

This single system master cylinder (used on M375 models up to February 1971) has one hydraulic pressure system, the cylinder has one reservoir and the residual check valve is in the cylinder bore.


Figure 1



SERVICE PROCEDURES

Removal

  1. Disconnect push rod from brake pedal.
  2. From engine compartment, disconnect brake line from master cylinder.
  3. Remove four master cylinder attaching nuts and washers and withdraw master cylinder from bracket.
  4. Place master cylinder on bench for further disassembly.

Disassembly

  1. Clean outside of master cylinder thoroughly.
  2. Remove reservoir filler plug and drain.
  3. Remove boot, stop retainer, piston stop and end plug stop. Inspect and replace if necessary (Figure 1).
  4. Remove piston, cups, return spring and valve assembly.

If piston is scored or corroded, replace with a new piston. Old piston cup should be discarded when reconditioning the master or wheel cylinder. Check rubber portion of valve assembly. If cracked or if it shows signs of deterioration, valve should be replaced.
Be sure relief port in master cylinder is open.

Master cylinder walls with light scratches or showing signs of corrosion, can usually be cleaned up with crocus cloth. However, cylinders with deep scratches or scoring may be honed provided diameter of cylinder bore is not increased more than .002 inches.

Assembly

  1. Before assembling, piston, cups and valve assembly should be washed in alcohol, dried with compressed air, then dipped in clean brake fluid to facilitate assembly.
  2. Install check valve and spring in cylinder with valve toward outlet of cylinder.
  3. Install master cylinder cup in cylinder with open end of cup over closed end of return spring.
  4. Install secondary cup on piston and install piston, piston stop and stop retainer.
  5. Install boot and push rod.

Installation

  1. Install master cylinder on vehicle.
  2. Connect brake line, fill and bleed system.
  3. Adjust "free p1ay" if necessary (1/8 inch.)