OPERATION
When the brakes are applied fluid pressure is exerted
against the caliper piston (2). The fluid pressure is
exerted equally and in all directions. This means pres-
sure exerted against the caliper piston and within the
caliper bore will be equal.
Fluid pressure applied to the piston is transmitted
directly to the inboard brake pad (5). This forces the
pad lining against the inner surface of the disc brake
rotor. At the same time, fluid pressure within the piston
bore forces the caliper to slide inward on the mounting
bolts. This action brings the outboard brake pad lining
(6) into contact with the outer surface of the disc
brake rotor.
In summary, fluid pressure acting simultaneously on
both piston and caliper, produces a strong clamping
action. When sufficient force is applied, friction will
attempt to stop the rotors from turning and bring the vehicle to a stop.
Application and release of the brake pedal generates only a very slight movement of the caliper and piston. Upon
release of the pedal, the caliper and piston return to a rest position. The brake pads do not retract an appreciable
distance from the rotor. In fact, clearance is usually at, or close to zero. The reasons for this are to keep road debris
from getting between the rotor and lining and in wiping the rotor surface clear each revolution.
The caliper piston seal (4) controls the amount of piston (2) extension needed to compensate for normal lining wear.
During brake application, the seal is deflected outward
by fluid pressure and piston movement(6). When the
brakes (and fluid pressure) are released, the seal
relaxes and retracts the piston (3).
The amount of piston retraction is determined by the
amount of seal deflection. Generally the amount is just
enough to maintain contact between the piston and
inboard brake pad.
REMOVAL
FRONT DISC BRAKE CALIPER
1. Raise and support vehicle.
2. Remove front wheel and tire assembly.
3. Drain small amount of fluid from master cylinder brake reservoir with clean suction gun.
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BRAKES - BASE - SERVICE INFORMATION
WK