2001 GMC Savana 3500 Brake Service (ONLINE REPAIR MANUALS)

Brake Lines & Linings

Remove one of the front wheels and inspect the brake disc, caliper and linings.

Do not allow any oil or grease on the linings. It is recommended that linings be replaced in sets when worn or damaged.

If the caliper is cracked or fluid leakage through the casting is evident, it must be replaced as a unit.

Brake Roughness

The most common cause of brake chatter on disc brakes is a variation in thickness of the disc. If roughness or vibration is encountered during highway operation or if pedal pumping is experienced at low speeds, the disc may have excessive thickness v...

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...

Height Sensing Proportioning Valve

The height sensing proportioning valve must be adjusted whenever the valve and/or linkage is disassembled or removed for service. In addition, adjustment should be checked if excessive front wheel lock-up is experienced with a lower than desired brake application rate when vehicle is at or near maximum GVWR.

• Raise and support vehicle, leave wheels on and allow axle to hang freely.
• Remove lever retaining nut and disconnect lever from valve shaft, Fig. .
• Rotate valve shaft to permit installation of correct adjustment gauge, Fig. , ensure D shaped ho...

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...

Master Cylinder

• On models equipped with manual brake system, disconnect master cylinder pushrod from brake pedal.
• On all models, disconnect all wire conne...

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...