1990 Ford Bronco II Brake Service (ONLINE REPAIR MANUALS)

SERVICE BRAKE

The rear brake shoes, Figs. and , adjust automatically when the vehicle is driven forward or reverse and the brakes are applied sharply several times. Manual adjustment is required only when brake shoes are replaced. When adjusting rear brakes, ensure that parking brake is properly adjusted and that equalizer is operating freely.

With Drums Removed

• With drums removed, clean areas where shoes contact backing plate, then apply suitable lubricant to these contact areas, ensuring that lubricant does not contaminate linings.
• Using suitable brake shoe adjusting gauge, ad...

The single and tandem vacuum boosters are self contained vacuum hydraulic power braking units. These are vacuum suspended units that use vacuum and atmospheric pressure for their power.

On gasoline engine vehicles, vacuum is supplied through a fitting in the intake manifold. On diesel engine vehicles, vacuum is supplied through a vacuum pump.

The three basic elements of the booster are the vacuum power chamber, mechanically actuated booster check valve an...

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...

EXCESSIVE PEDAL TRAVEL

• Worn brake lining.
• Shoe and lining knock back after cornering or rough road travel.
• Piston and shoe and lining assembly not properly seated or positioned.
• Air leak or insufficient fluid in system or caliper.
• Loose wheel bearing adjustment.
• Damaged or worn caliper piston seal.
• Improper booster pushrod adjustment.
• Shoe out of flat more than .005 inch.
• Rear brake automatic adjusters inoperative.
• Improperly ground rear brake shoe and lining assemblies.

BRAKE ROUGHNESS OR CHATTER; PEDAL PUMPING

• Excessive lateral runout of rotor.
• Rotor excessively out of parallel.

EXCESSIVE P...

MASTER CYLINDER

The master cylinder consists primarily of a hydraulic cylinder, primary and secondary hydraulic pistons and a single or dual chamber fluid reservoir. The front brakes are connected to the primary outlet port(s) and are actuated by the primary piston assembly. The rear brakes are connected to the secondary outlet port and are actuated by the secondary piston assembly.

HYDRAULIC CONTROL VALVES

Combination Valve

This multi-function hydraulic control unit consists primarily of a pressure differential valve, brake lamp warning switch and a proportioning valve. A pressure diff...

Make sure booster rubber reaction disc is properly installed as shown in Fig. , if the master cylinder pushrod is removed or accidentally pulled out. A dislodged disc may cause excessive pedal travel and extreme operation sensitivity. The disc is black compared to the silver colored valve plunger that will be exposed after pushrod and front seal are removed. The booster unit is serviced as an assembly and must be replaced if the reaction disc cannot be properly installed and aligned, or if it cannot be located within the unit itself.

• Disconnect battery ground cable.
• Disconn...