1991 Buick Century Brake Service (ONLINE REPAIR MANUALS)

• Grease or any other foreign material must be kept off the brake linings, caliper, surfaces of the disc and external surfaces of the hub, during service procedures. Handling the brake disc and caliper should be done in a way to avoid deformation of the disc and nicking or scratching brake linings.
• If inspection reveals rubber piston seals are worn or damaged, they should be replaced immediately.
• During removal and installation of a wheel assembly, exercise care so as not to interfer...

ADJUSTMENTS

Brake Pedal

• With engine running and brake pedal in rest position, measure distance between face of pedal and floor mat.
• If distance is not 5.79-6.18 inches, adjust pedal height as follows:
• Remove left lower instrument panel trim section and air duct.
• Loosen stop lamp switch sufficiently to gain clearance for pedal adjustment.
• Loosen locknut and rotate pedal pushrod as needed to obtain specified pedal height, then tighten locknut.
• Adjust position of brake light switch so that plunger lightly contacts pedal stopper and brake lamps are off when pedal is release...

Two basic types of power assist mechanisms are used: vacuum assist diaphragm assemblies, which use engine vacuum or, in some cases vacuum pressure developed by an external vacuum pump. The second type is a hydraulic pressure assist mechanism, which use pressure developed by an external pump (usually the power steering pump). Both systems act to increase the force exerted on the master cylinder piston by the operator. This in turn increases the hydraulic pressure delivered to the wheel cylinders, while decreasing driver effort necessary to obtain acceptable stopping performance.

V...

Servicing of disc brakes is extremely critical due to the close tolerances required in machining the brake disc to insure proper brake operation.

The maintenance of these close controls of the shape of the rubbing surfaces is necessary to prevent brake roughness. In addition, the surface finish must be non-directional and maintained at a micro inch finish. This close control of the rubbing surface finish is necessary to avoid pulls and erratic performance, and to promote long lining life and equal lining wear of both left and right brakes.

In light of the foregoing remarks, ref...

ADJUSTMENTS

Brake Pedal

• With engine running and brake pedal in rest position, measure distance between face of pedal and floor mat.
• If distance is not 5.79-6.18 inches, adjust pedal height as follows:
• Remove left lower instrument panel trim section and air duct.
• Loosen stop lamp switch sufficiently to gain clearance for pedal adjustment.
• Loosen locknut and rotate pedal pushrod as needed to obtain specified pedal height, then tighten locknut.
• Adjust position of brake light switch so that plunger lightly contacts pedal stopper and brake lamps are off when pedal is release...

• Raise and support vehicle.
• Remove wheel, drum and brake shoes.
• Disconnect hydraulic line at wheel cylinder.Do not pull metal line away from cylinder, as this may kink or bend line. Line will separate from cylinder when cylinder is moved away from brake backing plate.
• Remove wheel cylinder-to-brake plate attaching screws, then the wheel cylinder.
• Remove boots, pistons, springs and cups from cylinder,Fig. .
• Clean all parts with brake fluid.
• Inspect cylinder bore. A scored bore may be honed as long as the diameter is not increased by m...