On newer vehicles (including those with ABS), the master cylinder is a composite design (plastic reservoir and aluminum body). It is used in a diagonally split system (one front and one diagonally opposite rear brake served by the primary piston, and opposite front and rear brakes served by the secondary piston). Left front and right rear are on the same circuit, and the right front and left rear are on the same circuit.
The functions of a standard dual master cylinder are incorporated; in addition, it has a fluid level sensor and integral proportioners. The proportioners are designed to provide better front to rear braking balance with heavy brake application.
See Figure 1
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.
- Unplug the electrical connection from the fluid sensor.
- Use a flare nut wrench to disconnect the hydraulic lines from the master cylinder. Plug or cap the lines to avoid contaminating the system.
- Unfasten the two master cylinder-to-power booster retaining nuts or bolts, then remove the master cylinder from the vehicle.
See Figures 2, 3 and 4
- If installing a new master cylinder, bench bleed the master cylinder, as per the procedure located later in this section.
- Place the master cylinder in position on the booster. Connect the booster pushrod.
- Install the master cylinder retaining bolts and tighten to 20 ft. lbs. (27 Nm).
- Unplug and connect the fluid lines to the master cylinder.
- Attach the electrical connector to the fluid level sensor.
- Connect the negative battery cable.
See Figure 5
- Fill the master cylinder to the proper level, then bleed the brake system, as outlined later in this section.