REMOVAL & INSTALLATION
See Figures 1 through 8
- Remove the cover on the master cylinder and siphon enough fluid out of the reservoirs to bring the level to 2 / 3 full. This step prevents spilling fluid when the piston is pushed back.
- Raise and support the vehicle. Remove the front wheels and tires.
- Push the brake piston back into its bore using a C-clamp to pull the caliper outward.
- Unfasten the brake hose fitting from the caliper using a flare nut wrench, cap the fitting to prevent foreign material from entering the or the hose.
- Remove the two bolts which hold the caliper and then lift the caliper off the disc.
- Remove the inboard and outboard shoe.
If the pads are to be reinstalled, mark them inside and outside.
- Remove the pad support spring from the piston.
- Remove the two sleeves from the inside ears of the caliper and the 4 rubber bushings from the grooves in the caliper ears.
- Remove the caliper.
- Check the inside of the caliper for fluid leakage; if so, the caliper should be overhauled.
- Lubricate the sleeves, rubber bushings, bushing grooves, and the end of the mounting bolts using silicone lubricant.
- Install new bushing in the caliper ears along with new sleeves. The sleeve should be replaced so that the end toward the shoe is flush with the machined surface of the ear.
- Install the brake pads.
- 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.
- Fill the cavity between the bolt bushings with silicone grease. 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, sleeves and bolt boots.
- 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.
- Connect the brake hose to the caliper and tighten the fitting until the are snug.
- 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, and 0.010-0.028 in. (0.26-0.71mm) on 1992-98 models. If not, loosen the bolts and reposition the caliper.
- Install the front wheel and lower the truck.
- Add fluid to the master cylinder reservoirs so that they are 1 / 4 in. (6mm) from the top.
- Bleed the brake system.
- Check the fluid level again and add fluid as necessary. Do not move the vehicle until a hard pedal is obtained.
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.
- Raise and support the front end on jackstands. Remove the front wheels and tires.
- Push the piston back into its bore. This can be done by suing a C-clamp.
- Unscrew the brake line at the caliper. Plug the opening. Discard the copper washer. Be careful not to damage the brake line.
- 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.
- Remove the brake pads from the caliper.
- Lubricate the caliper support and support spring with silicone.
- Install the brake pads.
- 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.
- Use a brass drift pin to remove the key and spring.
- Install the screw and tighten to 15 ft. lbs. (20 Nm). The boss must fit fully into the circular cutout in the key.
- Using a new copper washer, connect the brake line at the caliper. Tighten the connector to 33 ft. lbs. (45 Nm).
- Bleed the brake system.
- Install the wheel.
Some vehicles may be equipped dual piston calipers. The procedure to overhaul the caliper is essentially the same with the exception of multiple pistons, O-rings and dust boots.
- Remove the caliper from the vehicle and place on a clean workbench.
Depending upon the vehicle, there are two different ways to remove the piston from the caliper. Refer to the brake pad replacement procedure to make sure you have the correct procedure for your vehicle.
The first method is as follows:
- Stuff a shop towel or a block of wood into the caliper to catch the piston.
Remove the caliper piston using compressed air applied into the caliper inlet hole. Inspect the piston for scoring, nicks, corrosion and/or worn or damaged chrome plating. The piston must be replaced if any of these conditions are found.
- For the second method, you must rotate the piston to retract it from the caliper.
- If equipped, remove the anti-rattle clip.
- Use a prytool to remove the caliper boot, being careful not to scratch the housing bore.
- Remove the piston seals from the groove in the caliper bore.
- Carefully loosen the brake bleeder valve cap and valve from the caliper housing.
- Inspect the caliper bores, pistons and mounting threads for scoring or excessive wear.
- Use crocus cloth to polish out light corrosion from the piston and bore.
- Clean all parts with denatured alcohol and dry with compressed air.
- Lubricate and install the bleeder valve and cap.
- Install the new seals into the caliper bore grooves, making sure they are not twisted.
- Lubricate the piston bore.
- Install the pistons and boots into the bores of the calipers and push to the bottom of the bores.
- Use a suitable driving tool to seat the boots in the housing.
- Install the caliper in the vehicle.
- Install the wheel and tire assembly, then carefully lower the vehicle.
- Properly bleed the brake system.