Operation (Front)
Two machined abutments on the steering knuckle position and align the caliper fore-and-aft. See Figure .The guide pin bolts, sleeves, and bushings control the side-to-side movement of the caliper. Although there are different disc brake systems available, they operate and are serviced in the same manner. A square-cut rubber piston seal is located in a machined groove in the cylinder bore. This provides a hydraulic seal between the piston and the cylinder wall. See Fig 1 . The piston seal is designed to pull the piston back into the bore of the caliper when the brake pedal is released. This, along with the brake shoe retractor clips, maintains the proper brake shoe-to-rotor clearance. A molded rubber dust boot is installed in a groove in the cylinder bore and the piston, keeping contamination from the cylinder wall and the piston. See Fig 1 . The brake shoe lining material rides against the brake rotors braking surface. When the brakes are applied, the shoes apply pressure against the rotor, thus slowing the vehicle. As brake shoe linings wear, master cylinder reservoir brake fluid level will go down. If brake fluid has been added to the reservoir, overflow may occur if the piston is pushed back into the recessed position. An audible wear indicator is mounted on the outboard pad of the front disc brake assemblies. Upon contact with the brake rotor, this indicator emits a sound, signaling that brake shoes may need inspection or replacement.