Dual Piston Caliper
The front brake caliper
has a dual piston. Two mounting bolts hold the caliper in place. The caliper
is mounted on the steering knuckle. The caliper moves laterally on
the steering knuckle when the brakes are applied. The caliper is a one-piece
casting with the piston bore(s) in the inboard side. A square-cut
rubber seal fits in a groove in each piston bore. The square-cut rubber
seal provides a hydraulic seal between the piston and the caliper
bore.
The front disc brakes use a combination rotor and hub assembly. The
rotor is separate from the hub.
The rotor turns freely between the linings, until the caliper forces
the linings against the rotor. The vented area between the rotor braking surfaces
allows for efficient heat dissipation.
Rear Disc Caliper
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.
For more information on the park brake, refer to
System Description
in Park Brake.
Servicing Information
• | Replace all components included in the repair kits. |
• | Lubricate the parts as specified. |
• | Do not use lubricated shop air on the brake parts. Shop air can
damage the rubber components. |
• | If necessary, bleed all or part of the brake system after any
hydraulic component has been removed or disconnected. |
• | Replace brake pads in axle sets only. |
• | The torques specified are for dry, unlubricated fasteners. |
• | Perform service operations on a clean bench. Verify that the bench
is free from mineral oil and other contaminants. |
• | Use extreme care when doing any work around antilock components
in order to prevent damage or misalignment. |
• | Pump the brake pedal several times in order to make sure it is
firm prior to moving the vehicle. Do not move the vehicle until a firm pedal
has been obtained. Check the brake fluid level in the master cylinder after
pumping the brakes. |