The proportioning valves, which are threaded into the master cylinder, limit outlet pressure to the rear brakes after a predetermined rear input pressure has been reached. This is used when less rear apply force is needed, and to obtain optimum braking and to prevent rear wheel lock-up on vehicles with light rear wheel loads.
REMOVAL AND INSTALLATION
- Disconnect the negative battery cable.
- Use a turkey baster or equivalent tool to siphon the brake fluid from the master cylinder into a suitable container.
- Detach the electrical connector from the master cylinder.
- Remove the master cylinder reservoir.
- Remove the proportioning valve caps from the master cylinder.
- Remove the O-rings, springs and the valve pistons. Be very careful not to scratch the valves in any way.
- Remove the valve seals from the valve pistons.
See Figures 1 and 2
- Lubricate the new seals and the pistons with a suitable silicone grease. Place the seals on the valve pistons.
- Install the valve pistons and O-rings into the master cylinder.
- Install the valve cap assemblies and tighten to 20 ft. lbs. (27 Nm).
- Install the reservoir assembly. Attach the electrical leads.
- Connect the negative battery cable. Fill the master cylinder reservoir, then bleed the brake system as outlined later in this section.