OPERATION
Two machined abutments on the steering knuckle
position the caliper. The guide pin bolts, sleeves and
bushings control the side to side movement of the
caliper. The piston seal is designed to pull the piston
back into the bore of the caliper when the brake
pedal is released. This maintains the proper brake
shoe to rotor clearance (Fig. 13).
All the front brake forces generated during braking
of the vehicle are taken up directly by the steering
knuckles of the vehicle.
A square cut rubber piston seal is located in a
machined groove in the caliper cylinder bore. This
provides a hydraulic seal between the piston and the
cylinder wall (Fig. 13).
A rubber dust boot is installed in the cylinder bore
opening and in a groove in the piston (Fig. 13). This
prevents contamination in the bore area.
As front disc brake linings wear, master cylinder
reservoir brake fluid level will drop. Fluid level
should be checked after replacing linings.
Front disc brakes are equipped with an audible
wear sensor (Fig. 11) on the outboard brake pad. This
sensor emits a sound when the brake lining may
need inspection or replacement.
DISC BRAKES (REAR)
DESCRIPTION
The rear disc brakes are similar to the front disc
brakes, however, there are several distinctive fea-
tures that require different service procedures. The
single piston, floating caliper rear disc brake assem-
bly includes a hub and bearing assembly, adapter,
brake rotor, caliper, brake pads/linings.
The parking brake system on all vehicles equipped
with rear disc brakes consists of a small duo-servo
drum brake mounted to the caliper adapter. The
drum brake shoes expand out against a braking sur-
face (hat section) on the inside area of the rotor.
Vehicles are equipped with a caliper assembly that
has a 33.4 mm (1.31 in.) piston and uses a solid non-
vented rotor.
The caliper assembly on all applications float on rub-
ber bushings using internal metal sleeves which are
attached to the adapter using threaded guide pin bolts.
The adapter and rotor shield are mounted to the
rear suspension knuckles of vehicle. The adapter is
used to mount the brake shoes and actuating cables
for the parking brake system. The adapter also
mounts the rear caliper assembly to the vehicle. The
adapter has two machined abutments which are used
to position and align the caliper and brake pads for
movement inboard and outboard (Fig. 14).
OPERATION
Rear disc brakes operate similarly to front disc
brakes.
Fig. 12 Front Disc Brake Caliper Mounting
1 – BRAKE FLEX HOSE
2 – GUIDE PIN BOLTS
3 – CALIPER ASSEMBLY
4 – ROTOR
5 – STEERING KNUCKLE
6 – DRIVESHAFT
7 – LOWER CONTROL ARM
8 – BUSHINGS AND SLEEVES
Fig. 13 Piston Seal Function for Automatic
Adjustment
1 – PISTON
2 – CYLINDER BORE
3 – PISTON SEAL BRAKE PRESSURE OFF
4 – CALIPER HOUSING
5 – DUST BOOT
6 – PISTON SEAL BRAKE PRESSURE ON
JX
BRAKES
5 - 7
DESCRIPTION AND OPERATION (Continued)