Description & Operation: Calipers

WARNING: This page does not describe the selected car, but rather 12 other vehicles, including the 1999 Oldsmobile Bravada, 1999 GMC Sonoma, 1999 GMC Jimmy, 1999 GMC Envoy, and 1999 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.

The rear brake caliper housing has a single bore. The caliper mounts to the anchor bracket with two guide pin bolts. Fluid pressure behind the caliper piston increases when applying the brakes. Pressure exerts equally against the bottom of the piston and the bottom of the piston bores. The pressure that applies to the piston transmits to the inner pad. The pressure forces the pad against the inner rotor surface. The pressure that applies to the bottom of the piston bores forces the caliper to slide on the mounting bolts. The caliper slides to the center of the vehicle. Because the caliper is one piece, the sliding movement causes the outer section of the caliper to apply pressure against the back of the outer pad. The pressure then forces the pad against the outer rotor surface. As line pressure builds, the pads press against the rotor surfaces with increased force. The force brings the vehicle to a stop. When releasing the brake pedal, the line pressure releases. The seal and the seal groove cause the piston to retract slightly. Piston retraction causes less drag on the rotor by both pads. Outward movement of the piston and inward movement of the caliper automatically compensate for pad wear. As the pads wear, the increased area behind the piston fills with brake fluid from the master cylinder reservoir. The park brake is completely independent of the hydraulic braking system.