REMOVAL & INSTALLATION
See Figure 1
- Using a turkey baster or other device, remove as much brake fluid as possible from the reservoir.
- Disconnect the negative battery cable. Working under the dash, disconnect the master cylinder pushrod from the brake pedal. The pushrod cannot be removed from the master cylinder.
- Disconnect the stop light switch wires and remove the switch from the brake pedal, using care not to damage the switch.
- Disconnect the brake lines using a line or flare nut wrench on all brake line fittings from the master cylinder.
- Remove the attaching hardware from the firewall and remove the master cylinder from the vehicle.
- Reinstall in reverse of above order, leaving the brake line fitting loose at the master cylinder.
- Fill the master cylinder, and with the brake lines loose, slowly bleed the air from the master cylinder using the foot pedal. Refill the system, adjust brakes if necessary, road test the vehicle for proper operation.
- An alternative service procedure for bleeding (Step 1) the master cylinder is as follows. Mount the new master cylinder in a holding fixture. Be careful not to damage the housing. Fill the master cylinder reservoir with brake fluid. Using a suitable tool inserted into the master cylinder piston push tool in slowly while holding one outlet port closed. Place a suitable container under the master cylinder to catch the fluid being expelled from the outlet port. Place a finger tightly over each outlet port and allow the master cylinder piston to return. Repeat the procedure until clear fluid only (no air) is expelled from the all outlet ports on the master cylinder.
See Figures 2 through 9
The following procedure can be used on all years and models. Slight variations may occur but the procedure covers all years and models. Modify the service steps as necessary.
- Disconnect the negative battery cable.
- Using a turkey baster or other suitable device, remove as much brake fluid from the reservoir as possible.
- If equipped with a warning switch, disconnect the wire harness attached.
- Remove the brake lines from the primary and secondary outlet ports of the master cylinder. Use a flare wrench of a suitable size.
- Remove the nuts attaching master cylinder to the brake booster assembly.
- Slide the master cylinder forward and upward from the vehicle. Be careful of any dripping brake fluid.
Before installation, bench bleed the new master cylinder as follows:
- Mount the new master cylinder in a holding fixture. Be careful not to damage the housing.
- Fill the master cylinder reservoir with brake fluid.
- Using a suitable tool inserted into the booster pushrod cavity, push the master cylinder piston in SLOWLY. Place a suitable 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 master cylinder from the holding fixture.
- Mount the master cylinder to the booster. Install a new seal in the groove in the master cylinder mounting face, if equipped.
- Connect the brake fluid lines to the master cylinder. Start threading each fitting by hand to prevent the possibility of crossthreading.
- Attach the brake warning indicator switch connector, if equipped.
- Bleed the entire brake system. Operate the brakes several times, then check for external hydraulic leaks. Only when you are sure there are no leaks, and the pedal is firm, should you road test the vehicle.
See Figures 10 through 20
Use this service procedure and exploded view illustrations as a guide for overhaul of the master cylinder assembly. If in doubt about overhaul condition or service procedure replace the complete assembly with a new master cylinder assembly.
- Remove the cylinder from the car and drain the brake fluid.
- Mount the cylinder in a vise. Clean around the end of the cylinder. Using a snapring pliers, remove the ring and seal from the hub.
- If equipped, remove the stopscrew from the bottom of the front reservoir.
- Remove the piston assembly from the bore.
- Clean all the metal parts in brake fluid and discard the rubber parts.
- Inspect the bore for damage or wear, and check the pistons for damage and proper clearance in the bore. If worn, replace the parts or the entire assembly.
Some late model vehicles are equipped with aluminum master cylinders. DO NOT HONE! If the bore is pitted or scored deeply, the master cylinder assembly must be replaced.
- If the bore is only slightly scored or pitted it may be honed. Always use hones that are in good condition. Completely clean the cylinder with brake fluid when the honing is completed. If any evidence of contamination exist in the master cylinder, the entire hydraulic system should be flushed and refilled with clean brake fluid. Blow out the passages with compressed air.
The rebuilding kit may contain secondary and primary piston assemblies instead of just rubber seals. In this case, seal installation is not required.
- 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 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 properly.
- Coat the rear piston seals with brake fluid and install it 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. When correctly positioned, install the snapring.
- If equipped with a stopscrew, hold the piston train at the bottom of the bore and install the stopscrew.
- Install a new seal on the hub. Bench-bleed the cylinder or install and bleed the cylinder on the car.