Assembly - Reservoir

(1) Fit the reservoir jointing grommets into the cylin­ der locations and fit the "0" ring onto the reservoir attaching bolt.

(2) Install the reservoir over the attaching bolt and onto the grommets.

(3) Fit the reservoir attaching washer and nut and tighten to the specified torque.

(4) Assemble the reservoir cover metal plate and rub­ ber seal with the "front" markings aligned.

(5) Fit the cap to the reservoir with the "front" mark to the front of the vehicle, ensuring that the outside lip on the rubber seal fits over the locating bead on the reservoir.

TESTING MASTER CYLINDER

Checking if the master cylinder compensates at both ports can be achieved by applying the pedal lightly and observing for a geyser of fluid squirting up in the reser­ voirs. This will occur first in the rear reservoir and will immediately be followed by the front reservoir.

HYDRAULIC SYSTEM FAILURE WARNING SWITCH The hydraulic system warning switch is used to warn the vehicle operator that one of the hydraulic systems has failed.

A failure in one circuit does not result in a failure of the entire brake system.

As pressure in one circuit falls, the unbalance in pres­ sure on the spool valve forces the valve to move and contact the switch terminal thus lighting the brake failure warning lamp on the instrument cluster.

The warning lamp switch components are installed in the master cylinder in the same bore as the proportioning valve, Figs. 5 & 6.

The warning lamp switch spool valve is self neutralizing, thus it is not necessary to remove the switch to allow the valve to centralize.

The switch can be removed or replaced without loss of fluid.

REV. OCT. '78

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5 - 3A - 6

PROPORTIONING VALVE

The proportioning valve is integral with the master cylinder. Its purpose is to regulate the amount of fluid pressure transmitted to the rear hydraulic circuit thus pre­ venting premature rear wheel "lock up" resulting in im­ proved braking and steering control under braking.

NOTE: Station wagons fitted with the PBR Sliding Head Calipers have the proportion valve deleted from the master cylinder. The body of this cylinder is coloured gold.

The valve contains a stepped piston working against a pre-loaded spring and poppet valve (refer Fig. 5). This allows the front and rear hydraulic pressure to increase at the same rate until the piston overcomes the spring force. At this point the piston will begin to move across to the poppet valve thus restricting the pressure increase to the rear brakes.

In the event of a front circuit failure, the poppet valve will be pulled away from the proportioning valve piston by the spool valve, allowing all available pressure to be transmitted to the rear brakes unrestricted.

Testing

When a premature rear wheel "lock up" is obtained on brake application, it usually is an indicator that a mal­ function has occurred within the proportioning valve; test as follows:

(1) Remove the rear brake tube from the master cylin­ der and "T" a 13800 kPa (2000 p.s.i.) gauge between the master cylinder and brake tube, "T" a similar gauge onto one of the front tubes.

NOTE: Ensure all joints are Ouid tight.

(2) With an assistant exerting pressure on the brake pedal, obtain a front circuit pressure output of approxi­ mately 4826 kPa (700 p.s.i.).

(3) While pressure is being held at above, reading on rear circuit gauge should be 3971 to 4391 kPa (576 to 637 p.s.i.).