How to Repair a Brake Booster in an 85 Ford Ranger

A power brake booster failure in a 1985 Ford Ranger is largely attributable to a failed diaphragm in the booster housing. There are few reasons for such a failure other than normal wear or a leak in the rear of the brake master cylinder. Such a leak causes brake fluid to permeate into the diaphragm, causing it to rip prematurely.

Instructions

1

Move the drivers seat all the way to the rear. Assume a position on the drivers floor where the top of the brake pedal can be seen clearly. Pull the electrical plug out of the stop light switch on the top of the brake pedal.

2

Pull the retaining pin out of the brake pedal stud which the brake rod and switch are mounted using a needle-nose pliers. The pin is on the far left side of the switch. Once the pin is out, pull off a washer and the brake rod with the brake light switch attached.

3

Move to the engine compartment and remove the two nuts securing the master cylinder to the power brake booster using a socket. Tie a piece of rope or wire to the master cylinders top cover-securing arm. Pull the master cylinder off the studs gently and tie it to the fender apron through one of the holes. This will support the master cylinder while you remove the power booster.

4

Move back inside and remove the four nuts securing the brake booster to the firewall using the extension with a universal to reach the top nuts. Move to the engine compartment again and unfasten the clamp securing the vacuum booster hose using a socket and ratchet. Pull the hose with the one-way valve attached out of the power booster. Pull the power brake booster out of the firewall.

5

Install the new power brake booster by inserting the brake rod through the firewall. Align the booster studs with the holes in the firewall and push it in. Move under the dash and install the nuts to the booster studs where they come through the firewall. Torque the nuts to 25 foot-pounds.

6

Move back to the engine compartment and install the brake master cylinder on the two booster studs. Install the nuts to secure it to the booster and torque them to 25 foot-pounds. Plug the vacuum one-way valve into the brake booster housing. Install the hose-retaining clamp on the booster.

7

Move under the dash and install the brake light switch over the brake push rod from the booster. Align the hole in the switch with the hole in the rod and place it on the brake pedal stud on the top left side of the brake pedal. Place the last washer on the stud to the left side of the switch and install the retaining pin through the hole in the end of the stud. Plug the electrical connector into the brake light switch.