At the specified intervals, remove the front road-wheels and inspect the thickness of the pad material remaining, checking the ends of the outboard shoes by looking in at each end of the caliper, while the inboard shoe can be checked through the inspection hole at the top of the caliper; pads should be replaced when worn down to inch thickness over the rivet heads. Most models are equipped with an audible warning device that indicates when the disc pads have worn down to their safe limit, emitting a squeal when the friction material has worn down to 0.030 inches. To replace the disc pads, ensure the brake fluid reservoir is no more than three-quarters full, siphoning off any excess fluid. Raise the front end of the vehicle and remove the wheels, performing the disc pad replacement on one brake assembly at a time, using the assembled brake for reference if necessary. Push the piston back into its bore, using a C-clamp or flat bar as needed, ensuring the fluid in the master cylinder reservoir does not overflow. Remove the two mounting bolts attaching the caliper to the support, then lift off the caliper. Remove the shoes and position the caliper so that the brake hose does not support its weight, marking the position of the disc pads if they are to be re-installed. Remove the shoe support spring from the piston, the two sleeves from the inboard ears of the caliper, and the four rubber bushings from the grooves in each caliper ear, then clean the holes and bushing grooves in the caliper ears. Examine the inside of the caliper for signs of fluid leakage; if evident, the caliper should be overhauled. When installing, ensure the caliper is clean and the dust boot is undamaged, lubricating new sleeves, rubber bushings, bushing grooves, and the ends of the mounting bolts with brake lube. Install the rubber bushings on the caliper ears, then install the sleeves to the inboard ears so that the end towards the shoe is flush with the machine surface of the ear. Install the shoe support spring and inboard shoe in the center of the piston cavity, pushing down until the shoe is flat against the caliper. 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, ensuring that if equipped with a wear sensor, it goes towards the rear of the caliper. With the shoes installed, lift the caliper and rest the bottom edge of the outboard lining on the outer edge of the disc to ensure no clearance exists between the tab at the bottom and the caliper abutment. Position the caliper over the disc, lining up the holes in the caliper ears and mounting bracket, then install the mounting bolts, ensuring they pass under the retaining ears of the inboard shoe and through the holes in the outboard shoe and caliper ears into the mounting bracket, and torque-tighten the bolts. Pump the brake pedal to seat the linings on the disc, then bend the upper ears of the outboard shoe until no radial clearance exists between the shoe and the caliper housing. Install the front wheel and lower the vehicle, servicing the other side using the same procedures. Finally, add brake fluid to the master cylinder reservoir until it is three-quarters inch from the top, pump the brake pedal several times until satisfactory pedal action is obtained, and top up the master cylinder reservoir again if necessary.
Posted by GMPartsGiant Specialist 
