1982-86 vehicles are equipped with brake proportioning valves of several different types. The valves all do the same job, which is to separate the front and rear brake lines, allowing them to function independently and preventing the rear brakes from locking before the front brakes. Damage, such as brake line leakage, in either the front or the rear brake system will not affect the normal operation of the unaffected system. If, in the event of a panic stop, the rear brakes lock up before the front brakes, it could mean the proportioning valve is defective. In that case, replace the entire proportioning valve.
REMOVAL & INSTALLATION
See Figure 1
- Remove the brake line tubes from the proportioning valve, then plug the openings to prevent dirt from entering the system.
- Remove the mounting bolt(s) and the valve from the vehicle.
- To install, reverse the removal procedures. Refill the master cylinder reservoir and bleed the brake system. Torque the brake pipe fittings to 12-14 ft. lbs. (17-20 Nm).
See Figure 2
These vehicles use two different type proportioning valves; an integral type which is incorporated into the master cylinder, and a separate type mounted on the firewall. The integral type is serviced with the master cylinder as an assembly. The procedure below is for the separate type.
Drain the fluid from the brake system as follows:
- Connect a rubber hose to each brake bleeder valve.
- Open each bleeder valve, while a helper slowly depresses the brake pedal.
- Repeat this procedure until the brake system is empty.
- Using a line wrench, disconnect the four brake lines from the valve.
- Loosen the mounting bolt and remove the valve from the vehicle.
- Position the valve assembly in the vehicle.
- Connect the four brake lines to the valve assembly, but do not fully tighten.
- Install the mounting bolt and tighten to 11-13 ft. lbs. (15-18 Nm).
- Refill the brake system with new DOT 3 brake fluid.
- Following proper procedures, bleed the entire brake system.
All proportioning valves used on all models are not adjustable. If a problem exist with the valve, the valve assembly (separate valves) or the master cylinder (integral valves) must be replaced.