Hydraulic System: Description and Operation
Hydraulic Brake ActuationCAUTION: 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.
The hydraulic brake actuation system consists of the following:
^ Adjustable pedals (optional)
^ Fixed brake pedal
^ Brake vacuum booster
^ Brake master cylinder
^ Brake tubes
^ Anti-lock brake system (ABS) components
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: Carefully read cautionary information on product label. For EMERGENCY MEDICAL INFORMATION seek medical advice. In the USA or Canada on Ford/Motorcraft products call: 1-800-959-3673. For additional information, consult the product Material Safety Data Sheet (MSDS) if available. 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, specified 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
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.
^ Brake master cylinder pistons apply hydraulic pressure to the 2 diagonal hydraulic circuits.
^ The anti-lock brake system (ABS) brake master cylinder cannot be overhauled, due to internal adjustments which require extensive special tools and fixtures. The repair is made by installing a new master cylinder only.
The brake master cylinder consists of:
^ brake master cylinder fluid reservoir
^ brake master cylinder body
Brake Master Cylinder Reservoir
NOTE: The brake master cylinder body and brake master cylinder reservoir are replaced as an assembly. The reservoir cannot be replaced separately from the brake master cylinder body.
The brake master cylinder reservoir:
^ is mounted to the brake master cylinder body.
^ holds fluid supply for each brake master cylinder hydraulic circuit.
^ provides visual maximum and minimum fluid level markings.
^ contains the brake master cylinder fluid level indicator switch.
The brake master cylinder fluid level indicator switch can be checked by putting a magnetic probe against the inside of the reservoir to activate the indicator switch.
Brake Tubes 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 tube fittings must be correctly flared to provide strong leakproof connections. When bending tubing to fit the underbody or rear axle contours, be careful not to kink or crack the tube.
If a section of brake tube 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.