See Figures 1 and 2
The 240, 260 and 280 Z models are equipped with a vacuum assisted proportioned braking system employing discs on the front and finned aluminum drums on the rear. The vacuum assist cylinder is 152.5mm in diameter on 1970-72 vehicles, and 190.5mm in diameter on 1973 and later models (except 2 + 2 models which use a 228.6mm). The S-16 Girling-Sumitomo disc brake calipers are the two-piston type and the rear brakes are self-adjusting, leading/trailing type. The parking brake is mechanical, employing cables for actuation of the rear drum brakes.
The master cylinder is a dual cylinder design so that failure of either the front or rear brakes causes the brake system at the opposite end of the vehicle to be sealed off at the master cylinder and continue to operate normally.
The Master-Vac assist system employs manifold vacuum against a diaphragm to assist in application of the brakes. The vacuum is regulated to be proportional to the pressure placed on the pedal.
The system also incorporates a warning light which is operated by a hydraulic electric switch which connects the front and rear hydraulic systems. If pressure in one system is not counterbalanced by pressure in the other, as when a leak causes it to be sealed off at the master cylinder, the switch piston is forced to one side and closes the warning light switch.
Ordinarily in a hydraulic brake system, application of pressure at the master cylinder causes equal pressure to be built up at all wheel cylinders or caliper pistons at the wheels. While this is appropriate during normal braking, weight transfer from the back wheels to the front (under very hard braking) lessens the rear brake pressure requirements. Stable braking cannot be achieved if the rear wheels cease to turn as the tire will track only if it is rolling along the road. As a result, a proportioning valve is used. The valve permits equal pressure in all parts of the system until the system pressure reaches a certain point. Then, through the motion of spring pistons in the valve, the rear brake pressure is throttled and maintained at a reduced percentage of front brake pressure.
On the 1970-72 models, the proportioning valve is located in the rear of the main brake line (going to the back of the vehicle), while in later model vehicles, it is located in the engine compartment and links the front and rear systems.
The ZX models are equipped with vacuum assisted disc brakes at all four wheels. The front discs are CL28V (1970-83), CL28VA or CL28VB single piston sliding caliper models with ventilated rotors (1984-88 except 1987-88 with turbo engine) and CL28VE, a dual piston sliding caliper on (1987-88 models equipped with the turbo engine). The rear brakes are Annette AN14H (1979-81) single piston sliding caliper, CL14H or CL14HB single piston sliding caliper (1982-86), or CL14HVB single piston sliding caliper (1987-88). The inner piston is equipped with a toggle and strut actuated parking brake mechanism which locks the inner pad against the solid rotor. A 228.6mm Master-Vac booster is used on all models and is similar to the one installed on the 1973-78 (2 + 2) Z but is not interchangeable. The warning light and proportioning valve systems are the same as those used on the Z series.