REMOVAL & INSTALLATION
See Figures 1 through 5
- Disconnect the negative battery cable.
- Tag and remove the brake lines from the primary and secondary outlet ports of the master cylinder.
- Unplug the brake warning indicator connector.
- Remove the nuts attaching the master cylinder to the brake booster assembly.
- Slide the master cylinder forward and upward from the vehicle.
Before installation, bench bleed the new master cylinder:
- Mount the new master cylinder in a holding fixture. Be careful not to damage the housing.
- Fill the master cylinder reservoir with clean brake fluid.
- Insert a small tool into the booster pushrod cavity; press the master cylinder pushrod in slowly. Place a container under the master cylinder to catch the fluid being expelled from the outlet ports.
- Place a finger tightly over each outlet port and allow the master cylinder piston to return.
- Repeat the procedure until clear fluid only is expelled from the master cylinder. Plug the outlet ports and remove the cylinder from the holding fixture.
- Mount the master cylinder on the booster.
- Attach the brake fluid lines to the master cylinder.
- Connect the brake warning indicator wiring.
- Bleed the system. Operate the brakes several times, then check for external hydraulic leaks. Connect the negative battery cable.
See Figures 6, 7 and 8
The most important thing to remember when rebuilding the master cylinder is cleanliness. Work in clean surroundings with clean tools. Use clean cloth or paper for drying purposes. Have plenty of clean alcohol and brake fluid on hand to clean and lubricate the internal components. There are service repair kits available for overhauling the master cylinder.
- Remove the master cylinder from the vehicle and drain the brake fluid.
- Pry the reservoir off the master cylinder with a large, flat tool.
- Mount the cylinder in a vise so that the outlets are up; remove the seal from the hub.
- Remove The proportioning valve from the cylinder.
- Remove the stopscrew from the bottom of the master cylinder.
- Depress the primary piston and remove the snapring from the bottom of the bore.
- Use compressed air to remove the secondary piston assembly. Cover the bore opening with a cloth to prevent damage to the piston.
- To remove the primary piston, use compressed air in the outlet port at the blind end and plug the other port.
- Clean the metal parts in brake fluid and discard the rubber parts.
- Inspect the bore for damage or wear and check the pistons for damage. Also check the pistons for proper clearance in the bore.
- If the master cylinder is not damaged, it may be serviced with a rebuilding kit. The rebuilding kit may contain secondary and primary piston assemblies instead of just rubber seals. In this case, seal installation is not necessary.
- Clean all parts in isopropyl alcohol.
- Install new secondary seals in the two grooves in the flat end of the front piston. The lips of the seals will be facing away from each other.
- Install a new primary seal and the seal protector on the opposite end of the front piston with the lips of the seal facing outward.
- Coat the seals with clean brake fluid. Install the spring on the front piston with the spring retainer in the primary seal.
- Insert the piston assembly, spring-end first, into the bore and use a wooden rod to seat it.
- Coat the rear piston seals with clean brake fluid and install them into the piston grooves with the lips facing the spring end.
- Assemble the spring onto the piston and install the assembly into the bore, spring first. Install the snapring.
- Hold the piston train at the bottom of the bore and install the stopscrew. Install a new seal on the hub.
Whenever the reservoir or master cylinder is replaced, new reservoir grommets should be used.
- Coat the new grommets with clean brake fluid and insert them into the master cylinder. Bench-bleed the cylinder or install and bleed the cylinder on the car.
- Press the reservoir into place. A snap should be felt, indicating that the reservoir is properly positioned.