REMOVAL & INSTALLATION
See Figures 1, 2, 3 and 4
Be careful not to spill brake fluid on the painted surfaces of the vehicle; it will damage the paint
- Unfasten the hydraulic lines from the master cylinder.
- Detach the hydraulic fluid pressure differential switch wiring connectors. Disconnect the fluid level sensor wiring connectors, if necessary.
- Loosen the master cylinder reservoir mounting bolt.
Then, do one of the following:
- On models with manual brakes remove the master cylinder securing bolts and remove the clevis pin from the brake pedal. Remove the master cylinder.
- On models with power brakes, unfasten the nuts and remove the master cylinder assembly from the power brake unit (vacuum booster).
- Before tightening the master cylinder mounting nuts or bolts, screw the hydraulic line into the cylinder body a few turns by hand-NEVER use a wrench to start threads.
- After installation is completed, bleed the master cylinder and the brake system as outlined later in this section
When replacing the the master cylinder it is best to BENCH BLEED the master cylinder before installing it to the vehicle. Mount the master cylinder into a soft jawed vise or suitable equivalent (do not damage the cylinder). Fill the cylinder to the correct level with new DOT 3 type brake fluid. Block off all the outer brake line holes but one, then position a long wooden dowel in the bore to actuate the brake master cylinder. Pump the brake master cylinder 3 or 4 times (push in and out with the dowel) until brake fluid is released and no air is in the brake fluid. Repeat this procedure until all brake fluid is released from every hole and no air is expelled
See Figures 5 through 15
- Remove the reservoir caps and floats. Unscrew the bolts which secure the reservoirs to the main body.
- Remove the pressure differential warning switch assembly. Then, working from the rear of the cylinder, remove the boot, snapring, stop washer, piston No. 1, spacer, cylinder cup, spring retainer, and spring, in that order.
- Remove the end-plug and gasket from the front of the cylinder, then remove the front piston stop bolt from underneath. Pull out the spring, retainer, piston No. 2, spacer, and the cylinder cup.
- Remove the two outlet fittings, washers, check valves and springs.
- Only remove the piston cups from their seats if they are to be replaced.
- After washing all parts in clean brake fluid, dry them with compressed air if available or allow them to air dry. Inspect the cylinder bore for wear, scuff marks, or nicks. Cylinders may be hones slightly, but the limit if 0.006 inch (0.15mm) In view of the importance of the master cylinder, it is recommended that it be replaced, rather than overhauled, if worn or damaged.
- Assembly is performed in the reverse order of disassembly. Absolute cleanliness is imperative. Coat all parts with clean brake fluid prior to assembly.
- Bleed the hydraulic system and the master cylinder.