caliper that is leaking, has worn or damaged seals, or is causing
brake pads to wear unevenly, needs to be rebuilt or replaced,
but so do many calipers that appear to be trouble-free.
three or four years of service, most caliper bores and steel
pistons have visible corrosion and pitting. As the surface of
the piston becomes rough, it starts to wear the piston seal.
Every time the brakes are applied, the roughness on the piston
scrapes back and forth across the seal. Eventually, the seal
will fail and the caliper will leak.
a caliper may not be leaking when the brakes are relined, there
is no guarantee how much longer the seals will remain leak free.
Seals and pads usually wear at the same time, so it does not
make much sense to fix one and not the other.
is extra expense and effort, but why should your customer have
to repeat a brake job in six months or a year when the caliper
he should have rebuilt or replaced starts to leak and ruins
the new pads you sold him?
a sliding caliper, only one side of the caliper has an apply
piston. The caliper moves in relation to the rotor and is held
in a frame rigidly attached to the steering knuckle.
linings wear, the piston gradually moves further out in the
caliper bore as the pads wear. When the piston is shoved back
in to accommodate new thicker pads, any dirt or corrosion on
the piston will be forced under the seal and accelerate seal
reason for rebuilding calipers is because rubber piston seals
deteriorate with age. A piston seal performs a two-fold function;
it seals the piston so hydraulic pressure can apply the brakes,
and it helps retract the piston when the brakes are released.
the piston is pushed out by the brake fluid, a square-cut seal
twists slightly. This helps pull the piston back when the pressure
is released, allowing pads to move away from the rotor more
easily for reduced brake drag and improved pad wear and fuel
ages the seal. Over time, it loses elasticity and becomes brittle.
This reduces its ability to deform and pull the piston back.
neglected caliper can become a dragging caliper, causing increased
pad wear, fuel consumption, and possibly a steering pull.
a caliper usually costs less than replacing it with a remanufactured
or new unit, but it does involve extra time and effort.
professionals prefer the convenience of replacing old calipers
with rebuilt units rather than rebuilding the calipers themselves.
If a caliper can't be rebuilt because of damage or severe wear,
replacement is the only option.