The braking system of a 1988 Mustang consists of more than just the brake pads and rotors. There is also the master cylinder, which controls the way the brakes operate. If there are problems with the master cylinder, your brakes will not work. When you depress the brake pedal, it sends fluid through the brake lines to stop your car. If there are problems with your master cylinder, do not operate the car until you repair it. The procedure depends on whether you have manual or power brakes.
Tools Used: Turkey baster, Drain pan, Wrench set, Brake fluid, 10W-40 oil, Torque wrench, Brake hose plugs (2)
Install Brake Master Cylinder
Manual Brakes
Open the hood to access the engine compartment. Disconnect the negative battery cable, loosening the terminal nut with a wrench. Remove as much of the brake fluid as possible from the cylinder reservoir with a turkey baster. Put the fluid in a drain pan for recycling.
Unplug the brake light switch at the brake pedal. Remove the spring retainer with a pair of pliers and slide the brake light switch from the brake pedal.
Disconnect the brake lines from the primary and secondary outlet ports on the master cylinder with a wrench. Remove the bolts that mount the master cylinder to the firewall with a wrench. Slide the push rod, nylon washers and bushings from the brake pedal pin. Remove the nuts that secure the master cylinder to the dash panel adapter with a wrench. Lift the master cylinder out of the car.
Insert the new master cylinder push rod through the dash panel adapter and position the master cylinder onto the panel adapter. Install the nuts into the dash panel. Apply 10W-40 motor oil to the nylon bushings and washers. Install the inner nylon washer, master cylinder push rod and the brake light switch bushing onto the brake pedal pin.
Line up the stop lamp switch so that it straddles the push rod with the slot on the pedal pin and the switch frame hole just clearing the pin. Slide the switch upward on the pin and push rod. Slide the assembly in toward the brake pedal arm. Install the outer nylon washer and the push rod retainer then lock it in place.
Attach the brake light switch connector. Tighten the master cylinder mounting bolts between 13 to 25 ft.-lbs. with a torque wrench. Connect the brake lines to the master cylinder with the wrench. Add brake fluid to the master cylinder to the recommended level.
Bleed the air from the brake lines starting with the point farthest from the master cylinder, which would be the passenger's side rear wheel. Have an assistant pump the brakes several times then hold the pedal while you open the bleeder valve with a wrench. Repeat this process on each wheel until the air is out of the system. Check the fluid level again to make sure it is at the proper level.
Power Brakes
Disconnect the brake lines from the master cylinder with a wrench. Plug the lines and the ports with brake hose plugs to keep out contaminants. Remove the nuts and lock washers for the master cylinder with a wrench.
Unplug the brake warning light connector. Slide the master cylinder forward and pull it off the booster.
Install the new master cylinder onto the studs of the booster assembly. Place the lock washers on the studs and tighten the nuts with a torque wrench between 13 and 25 ft.-lbs.
Connect the brake lines to the new master cylinder and tighten them with the wrench. Plug in the brake warning light connector.
Fill the reservoir to the recommended level with brake fluid. You will need to bleed the air from the system using the process from Step 7.
Tips & Warnings
Pump the brakes several times, after finishing the project, to check the new master cylinder for leaks.
Use only approved brake fluid in the master cylinder. For the 1988 Mustang, you must use DOT3 or DOT4 brake fluid. If you use anything else, you could cause damage to your brake system.
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