Self-Adjusting Brakes The single-piston
floating-caliper disc brake is self-centering and
self-adjusting. The caliper is able to slide from side
to side so it will move to the center each time the brakes are
applied. Also, since there is no spring to pull the pads away
from the disc, the pads always stay in light contact with the
rotor (the rubber piston seal and any wobble in the rotor may
actually pull the pads a small distance away from the rotor).
This is important because the pistons in the brakes are
much larger in diameter than the ones in the master
cylinder. If the brake pistons retracted into their
cylinders, it might take several applications of the brake
pedal to pump enough fluid into the brake cylinder to engage
the brake pads.
Self-adjusting disc brake
Older cars had dual or four-piston fixed-caliper designs. A
piston (or two) on each side of the rotor pushed the pad on
that side. This design has been largely eliminated because
single-piston designs are cheaper and more reliable.
