Important: • There is a heavy duty brake system (RPO CODE JA9) for the Autobahn package. The heavy duty brake system visually looks, and is repaired in the same manner as the standard duty brake system (RPO CODE JB9) except that it is larger in size than the standard duty brake system. Before servicing the brake system the RPO CODE must be checked before any repairs are started. • Replace all the components included in repair kits that are used to service this caliper. • Lubricate the rubber parts with clean brake fluid in order to ease assembly. • Do not use lubricated compressed air on brakes. Doing so may damage the rubber components. • Bleed the entire brake system whenever you remove any hydraulic component. • Replace the brake pads in the axle sets only. • The specified torque values are for dry, non-lubricated fasteners. • Perform service operations on a clean bench.
The front and rear calipers used on this vehicle have a single bore. The front and rear calipers mount to support brackets with two mounting 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.
