The disc brake assembly consists of a caliper
assembly, the rotor, and the lining assemblies mounted on the steering knuckle.
Applying the brake pedal causes the hydraulic pressure that moves the
caliper piston. The piston then forces the inboard brake lining assembly 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 assembly then contacts the outboard braking surface of the rotor.
The force of the two lining assemblies provides the desired clamping action
on the rotor.
Releasing the brake pedal relieves the pressure applied on the piston.
The square cut seal on the piston relaxes and the seal allows a running clearance
between the brake lining assemblies and the rotor.
Servicing Information
When servicing disc brake components, do the following:
| • | 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. |
Caliper Description
The brake caliper has a single 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) on 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.
Rotor Description
The front disc brakes use a combination rotor and hub assembly. The
rotor and hub are combined on RWD vehicles. The rotor is separate
from the hub on A4WD vehicles.
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.
