1987 Ford Bronco Master Cylinder Installation Instructions

When looking at more modern Ford Broncos, it is hard to imagine that it was originally a compact SUV that competed with the International Harvester Scout and Jeep CJ-5. It was not until the 1978 model year 12 years after the Broncos release that Ford made it into a full-size SUV to compete with the Chevy Blazer and other large SUVs. In 1987, Ford introduced two-wheel anti-lock brakes as a standard feature on the Bronco to go along with its power front disc brakes. Replacing the master cylinder the heart of the brake system on the 1987 Bronco is straightforward, but requires two separate bleeding processes.

Instructions

Removal

1

Press the brake pedal three or four times to purge any vacuum from the brake booster.

2

Unscrew the lid from the master cylinder reservoir and siphon out as much brake fluid as you can with a turkey baster. Transfer the fluid to a small container for disposal later.

3

Pull upward on the locking tab on the wiring harness connecting into the bottom of the reservoir, and pull the wiring harness from the reservoir.

4

Hold a small drain pan under the brake lines screwed into the master cylinder to catch dripping brake fluid. Loosen the brake line with a line wrench, and pull the brake lines from the master cylinder. Remove the container from under the brake lines once fluid stops dripping from them.

5

Wrap the ends of the brake lines with clean, lint-free cloths to prevent debris from getting into the brake system.

6

Remove the two master cylinder retaining nuts with a ratchet and socket. Pull the master cylinder away from the brake booster and out of the engine compartment.

Bench Bleeding

7

Set the new master cylinder into a bench vise equipped with rubber jaw protectors. Tighten the vise until it holds the master cylinder in place do not over-tighten the vise, as it may break the master cylinder.

8

Remove the plastic plugs from the brake line ports and hand-tighten bleeder lines from the master cylinder bleed kit into the ports. Tighten the bleeder line fitting with a line wrench. Remove the cap from the master cylinder reservoir and fill it to the Max line. Route the bleeder lines into the reservoir and submerge the ends of the lines in the brake fluid.

9

Press and release the plunger on the rear of the master cylinder just as the brake booster pushrod does with a wooden dowel, and watch the bleeder lines. Continue pressing and releasing the plunger until no more bubbles come from the ends of the bleeder hoses.

10

Unscrew the bleeder lines from the master cylinder with a line wrench and reinsert the plastic inserts into the brake line ports.

Installation

11

Set the new master cylinder on the mounting studs on the brake booster and hand-thread the retaining nuts. Torque the master cylinder-retaining nuts from 18 to 25 foot-pounds with a torque wrench and socket.

12

Remove the clean, lint-free cloths from the brake lines and pull the plastic inserts from the brake line ports in the master cylinder. Hand-thread the brake lines into the brake line ports they are hard-formed, so you cannot incorrectly install them and torque the front fitting from 16 to 21 foot-pounds and the rear fitting from 10 to 15 foot-pounds with a torque wrench and crows foot attachment.

13

Plug the wiring harness into the receptacle on the base of the master cylinder reservoir.

14

Fill the master cylinder to its Max level with fresh DOT 3 brake fluid, if needed.

Bleeding the Brake System

15

Raise the front of the Bronco with a floor jack, and slide jack stands under the SUVs frame rails. Lower the vehicle onto the jack stands. Raise the rear of the Ford with a floor jack and slide jack stands under the rear part of the Broncos frame. Lower the rear of the Bronco onto the jack stands.

16

Slide under the right rear wheel and find the bleeder valve the --inch metal valve on the top of the drum brake backing plate or the rear of the brake caliper. Press the end of a -inch-diameter rubber hose onto the bleeder valve and set the other end in a clean, clear container. Fill the clean, clear container with fresh DOT 3 brake fluid until it submerges the hose end.

17

Instruct an assistant to press and release the brake pedal repeatedly until it feels firm, then to hold pressure on the pedal. Open the bleeder valve by turning it counterclockwise with a combination wrench. Watch the end of the hose in the brake fluid and look for air bubbles to come from the hose. Tighten the bleeder valve. Repeat this step until no more air comes from the end of the hose.

18

Refill the brake master cylinder to its Max line with fresh DOT 3 brake fluid.

19

Repeat Steps 2 through 4 for the remaining three wheels, in the following order: left rear, right front and left front. Fill the reservoir after every wheel. If you let it run dry, you will have to start over.

20

Raise the rear of the Bronco off the jack stands with a floor jack and remove the jack stands. Lower the rear of the SUV to the ground. Raise the front of the Ford off the jack stands with a floor jack and remove the jack stands. Lower the front of the Bronco to the ground.
Pump the pedal until it is firm before driving the vehicle.