Hydraulic System: Description and Operation

Hydraulic Brake Actuation

CAUTION: Blistering or swelling of rubber brake components can indicate contamination of the brake fluid by a petroleum-based substance. Contaminated rubber components in the hydraulic brake system must be replaced and the entire hydraulic brake system must be flushed with clean brake fluid to prevent recontamination.

This vehicle is equipped with a brake pedal actuated dual brake system.

The dual brake system is split into front and rear circuits, with the front wheel brakes comprising one circuit and the rear wheel brakes comprising the other circuit.

The brake pedal is connected to the power brake booster by the brake master cylinder push rod.

When the brake pedal is depressed, brake fluid is pushed from the master cylinder through the metal tubing and flexible hoses to the rear disc brake calipers and the front disc brake calipers. The brake fluid enters the disc brake calipers, forcing the disc brake caliper pistons outward against the brake pads. The brake pads press against the braking surface on the brake discs.

Adjustable Brake Pedal
The vehicle has an (optional) adjustable brake pedal to increase driver comfort. The brake pedal position is changed in phase with the accelerator pedal. The system is adjusted by pressing the dash mounted switch that powers the drive motor mounted on the accelerator pedal assembly. The 2-way motor operates backward (away from the driver) or forward (toward the driver) to adjust the accelerator pedal directly and the brake pedal through the drive cable attached to the brake pedal assembly.

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.

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.

^ 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 depressed, pressure is applied by mechanical linkage to the primary and secondary master cylinder pistons.
^ Brake master cylinder pistons apply hydraulic pressure to the 2 hydraulic circuits.
^ Anti-lock brake system (ABS) brake master cylinder will not be overhauled, due to internal adjustments which require extensive special tools and fixtures. Service is made by replacement only.

The brake master cylinder consists of the:
^ brake master cylinder reservoir.
^ brake master cylinder body.

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 fluid level markings.
^ contains the brake master cylinder fluid level sensor.

Electronic Brake Distribution (EBD)
The electronic brake distribution (EBD) controls rear brake pressure and acts as an electronic proportioning valve. It is controlled by the anti-lock brake control module. When EBD is disabled, the brake warning indicator will illuminate.

Brake Tubes and Hoses

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

Steel tubing is used throughout the brake hydraulic system. All brake tube fittings must be correctly double flared to provide strong leakproof connections. When bending the 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, the entire section must be installed new with a tube of the same type, size, shape and length.

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