Disc Brakes System Description (Rear) - GMC chervolet camaro 1999 Service Manual

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Brakes
Front Brake Caliper
63980
The aluminum dual piston front caliper used on this
vehicle is mounted onto the front brake caliper
mounting plate, and ultimately to the steering knuckle.
Applying the brake pedal creates hydraulic pressure.
This pressure exerts equally against the bottom of the
pistons and against the bottom of the cylinder bores.
The pressure applied to the pistons transmits to
the inner pad and forces the pad against the inner
rotor surface. The pressure applied to the bottom of
the cylinders forces the caliper to slide in the
caliper bolt bushings toward the center of the vehicle.
This movement forces the outer section of the
caliper against the back of the outer pad and presses
the pad against the outer rotor surface. As hydraulic
pressure builds, the pads press against the rotor
surface with increasing force. The increasing force
causes the vehicle to stop. In addition, it is this sliding
action that allows a disc brake caliper to compensate
for wear of the inner and outer pads. If upon
inspection, it is found that one pad is significantly
thicker or thinner than its counterpart, it would be an
indication that the caliper is not sliding freely, and
therefore not self-adjusting as it is should.
The brake caliper piston seals, while sealing the
hydraulic circuit at the wheels, have a second function.
These seals while firmly mounted in their channels,
do distort very slightly under brake actuation. When the
brakes are applied, the movement of the pistons out
Disc Brakes 5-83
of the caliper bores distort the piston seals. When the
brake pedal is released, the piston returns only as
far as the seal was distorted. While this distortion of
the seal shape is very minimal, it is enough to
allow the brake pads to retract very slightly so as to
eliminate any significant drag of the brakes.
Disc Brakes System Description {Rear)
Rear Brake Rotor
The rear brake rotor is a composite cast iron ventilated
rotor. The rear brake rotor has a stamped sheet metal
flange which is insert cast. The internal fins or vanes
between the friction surfaces radiate from the center of
the rotor to the outer edge of the rotor. This design
enables the rotor to act as its own cooling fan.
Rear Brake Caliper
5
465589
The rear brake caliper has a single piston (1) in an
aluminum housing (2). The housing is suspended in an
anchor bracket (3) on two guide pins (4). The caliper
mounts to the steering knuckle with two mounting bolts.
Applying the brake pedal creates hydraulic pressure.
This pressure exerts equally against the bottom of the
piston and against the bottom of the cylinder bore. The
pressure applied to the piston transmits to the brake
pads (5). The brake pads clamp down on the rotor,
creating friction in order to stop the car.
Application of the parking brake causes the following
components to move outward:
• The pushrod (23)
• The actuating collar (10)
• The clamp rod (19)
The outward motion of the above components causes
the caliper to move inward. Inward motion of the
caliper forces the brake pads against the rotor in order
to hold the vehicle in place. The parking brake
mechanism is completely independent of the hydraulic
braking system.