Disc Brakes System Description Front
The disc brake assembly consists of a caliper assembly, rotor, linings, and anchor plate. Applying the brake pedal causes hydraulic pressure to move the caliper piston. The piston then forces the inboard brake lining against the inboard braking surface of the rotor. Increasing the force against the rotor causes the caliper assembly to move inboard. The outer brake lining then contacts the outboard braking surface of the rotor. The force of the two brake linings provides the desired clamping action on the rotor.
Releasing the brake pedal relieves the pressure applied to the piston. The square cut seal on the piston returns to normal position, allowing a running clearance between the brake linings and the rotor.
Servicing Information
Important:
• Before moving the vehicle, pump the brake pedal in order to make
sure the pedal is firm. Do not move the vehicle until you obtain a firm brake
pedal. Check the brake fluid level in the master cylinder reservoir after
pumping the brakes. • Replace all of the components included in the repair kits used
to service the front brake caliper. • Lubricate the rubber parts in order to ease assembly with Brake
Fluid GM P/N 1052535 or the equivalent. • Do not use lubricated compressed air on brake parts because rubber
component damage may result. • Flush the hydraulic brake system when installing new brake parts
with Brake Fluid GM P/N 1052535 or the equivalent. • After a hydraulic component has been removed or disconnected,
if needed, bleed all or part of the brake system. Refer to
Hydraulic Brake System Bleeding • Replace front brake pads in axle sets only. • The torques specified are for dry, unlubricated fasteners. • Perform service operations on a clean bench, free from mineral
oil and any other contaminants.
Front Brake Rotor (JB7/JB8)
When equipped with RPO JB7 or JB8, the rotor is integral with the hub assembly. During operation, the front brake rotor turns between the front brake linings and basically free-wheels until hydraulic pressure, created by applying the brake pedal, is converted by the front brake caliper to a stopping force. This force acts equally against the pistons and the bottom of the front brake caliper bore to move the pistons outward and move (slide) the front brake caliper inward, resulting in a clamping action on the front brake rotor. This clamping action forces the front brake pad linings against the front brake rotor, creating friction to stop the vehicle. The vented area between the rotor braking surfaces allows for efficient heat dissipation.
Front Brake Rotor (JF9)
When equipped with RPO JF9, the rotor and hub are separate components that are bolted together. During operation, the front brake rotor turns between the front brake linings and basically free-wheels until hydraulic pressure, created by applying the brake pedal, is converted by the front brake caliper to a stopping force. This force acts equally against the pistons and the bottom of the front brake caliper bore in order to move the pistons outward and move (slide) the front brake caliper inward, resulting in a clamping action on the front brake rotor. This clamping action forces the front brake pad linings against the front brake rotor, creating friction in order to stop the vehicle. The vented area between the rotor braking surfaces allows for efficient heat dissipation.
Front Brake Caliper (JB7/JB8)
The front brake caliper used on the P32/P42 equipped with RPO JB7 or JB8 is a single piston unit. The caliper is held in place by a support key, a spring, and a bolt assembly.
The caliper mounts to the anchor plate or steering knuckle in a way that allows the caliper to move laterally against the rotor. The caliper is a one-piece casting with the inboard side containing a piston bore. A square-cut rubber seal fits a groove in the piston bore in order to provide a hydraulic seal between the piston and caliper bore.
Front Brake Caliper (JF9)
The front brake caliper used on the P32/P42 equipped with RPO JF9 is a rail slider type with dual-pistons. A piston seal in a groove of the wall in each machined bore provides a hydraulic seal and retracts the piston when hydraulic fluid pressure is relieved. A dust boot keeps the caliper bore clean. A metal heat shield protects the dust boot from the heat caused by braking friction. The front brake caliper mounts using a front brake caliper retainer, a front brake caliper spring, and a front brake caliper retainer bolt to the front brake caliper mounting plate.
Disc Brakes System Description Rear
Rear axles equipped with disc brakes will utilize a rail slider type disc brake caliper (7).
The rear disc brake assembly consists of a brake caliper, brake rotor assembly, disc brake pad assembly, brake caliper mounting plate (3), and brake shield. The brake rotor assembly is bolted to the wheel hub and turns with the wheel. The brake caliper housing has machined bores and pistons. A seal in a groove of the wall in each bore provides a hydraulic seal and retracts the piston when fluid pressure is relieved. A dust boot; keeps the piston bore clean. A metal heat shield protects the dust boot from the heat caused by braking friction. The brake caliper is mounted by a brake caliper retainer and brake caliper retainer spring to the stationary brake caliper mounting plate. The brake caliper mounting plate and brake shield are bolted to the axle flange.
The brake pad assemblies are held in place on each side of the brake rotor. The outer brake pad moves with the brake caliper housing. The inner brake pad is held in place by the brake caliper mounting plate. All of the original equipment brake pad linings are free of asbestos.
Applying the brake pedal causes hydraulic pressure to move the brake caliper pistons. This causes the brake pads to clamp the brake rotor. The brake caliper adjusts the clamping position by sliding laterally in the support rails on the brake caliper mounting plate.
Releasing the brake pedal relieves the pressure applied to the brake caliper pistons. The pistons are pulled back in the bore by the action of the square cut piston seals running to the original shape. This allows for a running clearance between the brake pad linings and brake rotor.
Servicing Information
| • | Replace all components included in the repair kits used to service the brake caliper. |
| • | Lubricate rubber parts with clean brake fluid in order to ease assembly. |
| • | Do not use lubricated compressed air on brake parts because rubber component damage may result. |
| • | Flush the hydraulic brake system with clean brake fluid when you install new parts. |
| • | After a hydraulic component has been removed or disconnected, if necessary, bleed all or part of the brake system. Refer to Hydraulic Brake System Bleeding |
| • | Replace disc brake pads in axle sets only. |
| • | The torques specified are for dry, unlubricated fasteners. |
| • | Perform service operations on a clean bench, free from mineral oil and any other contaminants. |
| Important: Before moving the vehicle, pump the brake pedal several times to make sure the pedal is firm. Do not move the vehicle until a firm brake pedal has been obtained. Check the brake fluid level in the master cylinder after pumping the brakes. |
Rear Brake Rotor
The rear disc brakes use a brake rotor that is bolted to the hub assembly. During operation, the brake rotor turns between the linings and basically free-wheels until hydraulic pressure, created by applying the brake pedal, is converted by the brake caliper to a stopping force. This force acts equally against the pistons and the bottom of the brake caliper bore to move the pistons outward and move (slide) the brake caliper inward, resulting in a clamping action on the brake rotor. This clamping action forces the brake pad linings against the brake rotor, creating friction in order to stop the vehicle.
Rear Brake Caliper
The rear brake caliper is a rail slider type with dual-pistons. A seal in a groove of the wall in each machined bore provides a hydraulic seal and retracts the piston when fluid pressure is relieved. A dust boot keeps the piston bore clean. A metal heat shield protects the boot from the heat caused by braking friction. The brake caliper mounts using a brake caliper retainer, brake caliper retainer spring, and a brake caliper retainer screw to the brake caliper mounting plate.
