2001 Chevrolet Express 3500 Brake Service (ONLINE REPAIR MANUALS)

General System

• Inspect components for damage or unusual wear. Replace as required.
• Inspect backing plate mounting bolts and ensure they are tight.
• Inspect wheel cylinders. Excessive fluid indicates cup leakage and need for wheel cylinder replacement. Slight amount of fluid is always present and is considered normal, acting as lubricant for cylinder pistons.
• Check adjuster screw operation. If satisfactory, lightly lubricate adjusting screw and washer with suitable brake lube. If operation is unsatisfactory, replace.
• C clean rust and dirt from shoe contact surfaces on backing plate using fi...

G Series

• Remove brake pipes from master cylinder. Plug pipes to prevent fluid contamination.
• Remove master cylinder attaching nuts and position master cylinder aside.
• Disconnect stop lamp switch electrical connector.
• Remove stop lamp switch retainer from brake pedal pin, then the stop lamp switch from brake pedal support.
• Disconnect power brake unit pushrod from brake pedal.
• Remove attaching nuts, then the power brake unit.
• Reverse procedure to install.
• Torque booster retaining nuts to 27 ft. lbs.
• Torque master cylinder retaining nuts to 27 ft. lbs.
• Torque brake pipe fittings...

Excessive Pedal Travel

• Worn brake linings.
• Disc pads knock back after cornering or rough road travel.
• Piston and linings not properly seated or positioned.
• Insufficient fluid in system.
• Loose wheel bearing adjustment.
• Damaged or worn caliper piston seal.
• Improper booster pushrod adjustment.
• Pads out of flat more than .005 inch.
• Rear brake automatic adjusters inoperative.
• Improperly ground rear brake shoes.

Brake Roughness Or Chatter; Pedal Pumping

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

Excessive Pedal Effort

• Frozen or seized pistons.
• Brake fluid, oil or grease on ...

Master Cylinder

Some vehicles use a conventional tandem master cylinder with two hydraulic pistons operating in-line. The primary piston controls the front brake system and the secondary piston controls the rear brake system.

Other models use a master cylinder that operates the same as the conventional master cylinder, but also incorporates a quick take-up feature in the rear chamber to reduce excessive pedal travel which may result from increased fluid displacement required to move the low drag caliper piston out against the rotor.

The quick take-up uses a spring-loaded ball check val...

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, the amount of asbestos dust from brake lining wear is at a low level because of a chemical breakdown during use and a few precautions will minimize exposure. Do not sand or grind brake linings unless suitable local exhaust ventilation equipment is used to prevent ...

In order to properly service power brake systems, a thorough understanding of the power assist system is necessary. These systems provide a mechanical assist, acting to increase the force applied to the master cylinder piston by the driver while decreasing the effort necessary to obtain acceptable stopping performance.

Hydraulic assist units incorporate a basic open center spool valve, hydraulic cylinder and an accumulator assembly in a common housing. When the brake pedal is depressed, the hydraulic piston moves forward closing off fluid relief passages, the spool valve applies flui...