With Antilock Brakes

This vehicle uses 2 differently designed master cylinder assemblies depending on whether the vehicle is or is not equipped with antilock brakes.

Vehicles not equipped with ABS use a standard compensating port master cylinder design, while vehicles equipped with ABS use a center valve design master cylinder.

Vehicles equipped with rear drum brakes use a master cylinder with a 22 mm diameter piston bore. Vehicles equipped with rear disc brakes use a master cylinder with a 7/8 inch diameter piston bore.

On vehicles equipped with ABS brakes, the master cylinder is a two outlet design. On vehicles not equipped with ABS brakes, the master cylinder is a 4 outlet design. All vehicles are equipped with a master cylinder having a bore diameter of 22.2 mm.

Master Cylinder:

The master cylinder assembly consists of the following components. The body of the master cylinder is an anodized aluminum casting It has a machined bore to accept the master cylinder piston and threaded ports with seats for hydraulic brake line connections. The brake fluid reservoir of the master cylinder assembly is made of a see through polypropylene type Plastic.

Primary And Secondary Ports Without ABS:

On Non-ABS master cylinders, the primary outlet ports supply hydraulic pressure to the right front and left rear brakes. The secondary outlet ports supply hydraulic pressure to the left front and right rear brakes.

Master Cylinder Primary And Secondary Ports With ABS:

On ABS master cylinders, the primary outlet port supplies hydraulic pressure to the right front and left rear brakes. The secondary outlet port supplies hydraulic pressure to the left front and right rear brakes.

Master Cylinder And Vacuum Booster:

A vehicle equipped with the Teves Mark 20 ABS (without traction control) uses a different master cylinder and power brake booster then a vehicle that is not equipped with antilock brakes. A vehicle equipped with ABS uses a center port master cylinder while a vehicle which is not equipped with ABS uses a compensating port master cylinder.

The primary and secondary outlet ports on the master cylinder go directly to the Hydraulic Control Unit (HCU).


A fluid level switch is located in the master cylinder fluid reservoir. The switch closes when a low fluid level is detected. The fluid level switch turns on the brake warning lamp by grounding the lamp circuit. This switch does not disable the ABS system.