REMOVAL & INSTALLATION
See Figures 1 through 12
- Remove the cover on the master cylinder and siphon out 2 / 3 of the fluid. This step prevents spilling fluid when the piston is pushed back.
- Raise and support the front end on jackstands.
- Remove the wheels.
- Push the brake piston back into its bore using a C-clamp to pull the caliper outward.
- Remove the two bolts which hold the caliper and then lift the caliper off the disc.
- Remove the inboard and outboard shoe. Use a small prybar to disengage the buttons on the outboard shoe from the holes in the caliper housing.
If the pads are to be reinstalled, mark them inside and outside.
- Remove the pad support spring from the piston.
- Position the support spring and the inner pad into the center cavity of the piston, snap the retaining spring into the piston. The outboard pad has ears which are bent over to keep the pad in position while the inboard pad has ears on the top end which fit over the caliper retaining bolts. A spring which is inside the brake piston holds the bottom edge of the inboard pad.
- Push down on the inner pad until it lays flat against the caliper. It is important to push the piston all the way into the caliper if new linings are installed or the caliper will not fit over the rotor.
- Position the outboard pad with the ears of the pad over the caliper ears and the tab at the bottom engaged in the caliper cutout.
- With the two pads in position, place the caliper over the brake disc and align the holes in the caliper with those of the mounting bracket.
- Install the mounting bracket bolts through the sleeves in the inboard caliper ears and through the mounting bracket, making sure that the ends of the bolts pass under the retaining ears on the inboard pad.
For best results, always use new bushings, bolt sleeves and bolt boot.
- Tighten the mounting bolts to 35 ft. lbs. (47 Nm) for R/V Series; 28 ft. lbs. (38 Nm) for 1988-92 C/K Series and 38 ft. lbs. (51 Nm) for 1993-98 C/K Series. Pump the brake pedal to seat the pad against the rotor. Don't do this unless both calipers are in place. Use a pair of channel lock pliers to bend over the upper ears of the outer pad so it isn't loose.
After tightening the mounting bolts, there must be clearance between the caliper and knuckle at both the upper and lower edge. On R/V Series, the clearance must be 0.010-0.024 in. (0.26-0.60mm); on C/K Series, it must be 0.005-0.012 in. (0.13-0.30mm) for 1988-91 models, and 0.010-0.024 in. (0.26-0.60mm) on 1992-98 models. If not, loosen the bolts and reposition the caliper.
- Install the wheel and lower the truck.
- Add fluid to the master cylinder reservoirs so that they are 1 / 4 in. (6mm) from the top.
- Test the brake pedal by pumping it to obtain a hard pedal. Check the fluid level again and add fluid as necessary. Do not move the vehicle until a hard pedal is obtained.
See Figures 13, 14, 15 and 16
The Bendix system is used on some front brake applications and all rear brake applications.
- Remove approximately 2 / 3 of the brake fluid from the master cylinder. Discard the used brake fluid.
- Jack up your vehicle and support it with jackstands.
- Push the piston back into its bore. This can be done by using a C-clamp.
- Remove the bolt at the caliper support key. Use a brass drift pin to remove the key and spring.
- Rotate the caliper up and forward from the bottom and lift it off the caliper support.
- Tie the caliper out of the way with a piece of wire. Be careful not to damage the brake line.
- Remove the inner pad from the caliper support. Some rear disc brake shoe assemblies have a anti-rattle spring at the inner pad, after removing the inner pad, look for the anti-rattle spring and remove as necessary.
- Remove the outer pad from the caliper.
- Lubricate the caliper support and support spring, with silicone.
- If equipped on the rear disc brake assembly, install the anti-rattle spring in place before installing the inner pad.
- Install the lower end of the inboard shoe into the groove provided in the support. Slide the upper end of the shoe into position. Be sure the clip remains in position.
- Position the outboard shoe in the caliper with the ears at the top of the shoe over the caliper ears and the tab at the bottom of the shoe engaged in the caliper cutout. If assembly is difficult, a C-clamp may be used. Be careful not to mar the lining.
- Position the caliper over the brake disc, top edge first. Rotate the caliper downward onto the support.
- Place the spring over the caliper support key, install the assembly between the support and lower caliper groove. Tap into place until the key retaining screw can be installed.
- Install the screw and tighten to 15 ft. lbs. (20 Nm). The boss must fit fully into the circular cutout in the key.
- Install the wheel and add brake fluid as necessary.
See Figures 17 and 18
Support the truck on jackstands and remove the wheels. Look in at the ends of the caliper to check the lining thickness of the outer pad. Look through the inspection hole in the top of the caliper to check the thickness of the inner pad. Refer to the brake specifications chart at the end of this section for the brake pad minimum thickness.
These manufacturer's specifications may not agree with your state inspection law.
Original equipment pads and GM replacement pads have an integral wear sensor. This is a spring steel tab on the rear edge of the inner pad which produces a squeal by rubbing against the rotor to warn that the pads have reached their wear limit. They do not squeal when the brakes are applied.
The squeal will eventually stop if worn pads aren't replaced. Should this happen, replace the pads immediately to prevent expensive rotor (disc) damage.