1990 Ford Aerostar Brake Service (ONLINE REPAIR MANUALS)

The rear anti-lock brake system constantly monitors rear wheel speed. In the event of an impending rear brake lockup, the system regulates hydraulic pressure to the rear brakes, preventing total lockup when the brakes are applied and thereby reducing the possibility of skidding.

The system consists of a yellow warning light on the instrument panel, an electro-hydraulic rear anti-lock brake system (RABS) valve mounted on the frame rail behind the crossmember, a speed sensor mounted on the rear drive axle, an exciter ring mounted on the differential case and a comput...

When working on or around brake assemblies, care must be taken to prevent breathing asbestos dust, as many manufacturers incorporate asbestos fibers in the production of brake linings. During routine service operations precautions should be taken to minimize exposure. Do not sand or grind brake linings unless suitable local exhaust ventilation equipment is used to prevent excessive asbestos exposure.

• Wear a suitable respirator approved...

• Remove caliper and linings.
• Drain brake fluid from caliper housing, then position housing in a vise.
• Pad area between piston(s) and caliper bridge, then apply compressed air to caliper fluid port to remove piston(s). If piston is seized and cannot be forced from caliper, tap lightly around cylinder bore area while applying air pressure. Use caution when applying air pressure, as piston(s) may develop considerable force from pressure build-up.
• Remove and discard molded rubber boot(s) and square cut seal(s) from caliper assembly.
• Thoroughly clean piston(s) and caliper assembly using ...

Normal hydro-boost units will produce certain noises that current technology cannot correct. These noises occur when brake pedal is manipulated in a manner not associated with everyday braking habits. Normal operating noise can be a hissing, clunk, click or a chatter.

If above normal pedal efforts are applied, the hydra-boost unit will emit hissing noises. These noises will be particularly noticeable with the vehicle motionless and will increase in intensity as pedal efforts increase and system operating temperatures increase. Loud hissing noises at or below normal pedal effo...

To check adjustment of pushrod, fabricate a gauge and position it against master cylinder mounting ...

These assemblies consist of a caliper housing, bleeder screw, brake pads, mounting hardware, a single or dual piston, square cut seals and molded rubber dust boots. The rail slider-type calipe...