Hydraulic System: Description and Operation

Hydraulic Brake Actuation
The hydraulic brake actuation system consists of these components:
^ Brake pedal
^ Power brake booster
^ Brake master cylinder
^ Front disc brake calipers
^ Rear disc brake calipers
^ Rear drum brake cylinders
^ Brake lines and hoses
^ Anti-lock brake system (ABS) components (if equipped)

Brake Fluid

WARNING: Use of any other than approved DOT 3 brake fluid will cause permanent damage to brake components and will render the brakes inoperative. Failure to follow these instructions may result in personal injury.

WARNING: Brake fluid contains polyglycol ethers and polyglycols. Avoid contact with eyes. Wash hands thoroughly after handling. If brake fluid contacts eyes, flush eyes with running water for 15 minutes. Get medical attention if irritation persists. If taken internally, drink water and induce vomiting. Get medical attention immediately. Failure to follow these instructions may result in personal injury.

CAUTION: Brake fluid is harmful to painted or plastic surfaces. If brake fluid is spilled onto a painted or plastic surface, immediately wash it with water.

Use clean, fresh DOT 3 Motor Vehicle Brake Fluid.
^ Do not reuse brake fluid drained or bled from the system.
^ Do not use brake fluid that has been stored in an open container.
^ Do not use contaminated brake fluid.

Brake Master Cylinder

CAUTION: Blistering or swelling of rubber brake components may indicate contamination of the brake fluid by a petroleum based substance. If contaminated rubber components in the hydraulic brake system are found, new components must be installed, and the entire hydraulic brake system must be flushed with clean brake fluid to prevent recontamination.

NOTE: The master cylinder cannot be overhauled. Repair is made by installing a new master cylinder only.

The brake master cylinder is a dual piston type. The brake master cylinder operates as follows:
^ When the brake pedal is pressed, pressure is applied by mechanical linkage to the primary and secondary piston.
^ The brake master cylinder pistons apply hydraulic pressure to the 2 diagonal hydraulic circuits.
^ Diagonally split brake circuits (LH front to RH rear and RH front to LH rear).

The brake master cylinder consists of:
^ the brake master cylinder fluid reservoir.
^ the brake master cylinder body.
^ two pins that secure the reservoir to the master cylinder.

Brake Master Cylinder Reservoir

NOTE: Whenever the brake master cylinder reservoir is removed from the brake master cylinder, new grommets must be installed.

The brake master cylinder reservoir:
^ is mounted to the brake master cylinder.
^ holds fluid supply for each brake master cylinder hydraulic piston.
^ provides visual maximum and minimum fluid level markings.
^ contains the brake master cylinder fluid level sensor.

Brake Lines and Hoses

CAUTION: Never use copper tubing. It is subject to fatigue, cracking, and corrosion, which could result in brake tube failure.

Double wall steel tubing is used throughout the brake hydraulic system. All brake line fittings must be correctly double flared to provide strong leakproof connections. When bending tubes to fit the underbody or rear axle contours, be careful not to kink or crack the tube.

If a section of brake line is damaged, an entire new section must be installed with a tube of the same type, size, shape and length.

When installing new hydraulic brake tubing, hoses, or connectors, tighten all connections securely. After installation, bleed the brake system.

The wet appearance on the outer cover of rubber brake hoses is called sweating. This is a normal condition for neoprene rayon braid hose and is not a sign of leakage or cause for the installation of a new hose.

Pressure Conscious Reducing Valves (PCRVs)
The PCRVs are fitted between the master cylinder and the brake tubes to the rear wheels.
The PCRVs control the hydraulic pressure applied to the rear brakes, thereby reducing the risk of rear wheel lock-up under braking.