What Is a Brake Caliper
If your car is equipped with disc brakes, brake calipers are critical to slowing and
stopping your car. Here's what you need to know.
The brake caliper plays a central role in a disc-brake system and has two functions. First, it acts either as a bracket
to support the brake pads on either side of the rotor or to support the caliper bracket itself — there are other designs,
but these are the two most common. Second, it uses pistons to convert pressure exerted on the brake fluid by the master
cylinder into friction on the rotor.
In simple terms, a brake caliper’s purpose is to squeeze the brake pads against the rotor to stop the car. There are two
main types of calipers, a single piston and a dual piston. Most front calipers are dual piston but many cars use single
piston calipers on the rear, where less braking force is needed.
Stepping on the brake pedal forces the master cylinder piston forward, compressing the brake fluid. The brake fluid
forces the brake caliper pistons toward the rotors, pinching
the rotors in between the brake pads, which creates friction and slows the vehicle.
When Brake Calipers Go Bad
In general, brake pads and rotors wear out and need replacement far more often than calipers. A leading cause for damaged
calipers, however, stems from driving a vehicle on worn-out pads or warped rotors. Both prevent the system from dissipating
the heat of friction, as they’re designed to do, which can damage the calipers.
If the pads fail to insulate the caliper from excessive heat, the piston can be damaged or the heat can be passed through
the piston to the brake fluid, which can cause it to degrade. The latter can result in brake failure.
A damaged piston, or one that is simply corroded, may get stuck in one position. If it sticks in the retracted position,
that wheel will lose braking ability. If it sticks in the engaged position, the wheel will brake continuously until freed.
How to Tell That a Caliper Has Failed
With a retracted piston, the car may pull toward the side of the car with operating brakes when they are engaged. You may
also notice that braking distance increases. Conversely, an engaged piston will cause the car to pull toward the engaged
brake when driving. (Note: A stuck caliper can cause pulling, but there are many other possible causes as well.) Excess heat
will be present, and the brake pad will quickly wear down. Any of these symptoms indicate immediate need for service.
Another sign of caliper failure could include leaking brake fluid, as a damaged piston may no longer seal completely. If
enough fluid escapes from the system, the warning light on the dashboard will call your attention to it. If you check your
pad wear regularly, you may note uneven wear on the pads, comparing one side of the rotor to the other, or even left wheel to
right wheel. If the pads show uneven wear, check the caliper function. And yet another sign of a seized caliper is excessive
brake dust on one wheel compared to the other.
In the rarest form of failure, the caliper bracket could snap, causing a clunking sound when the brakes engage. If you
hear this, stop immediately and do not operate the vehicle.
Ignoring any of these symptoms can magnify the damage. The cost and effort required to address the problem increases
proportionally. Make an effort to examine the problem as soon as possible or have it evaluated by a qualified technician.
Important Maintenance Points
? As the brake pads wear, the caliper needs to stay centered on the rotor to allow for even pressure on both sides. There
are different ways manufacturers accomplish this, and some designs are better than others at keeping the calipers sliding to
compensate for pad wear. When brake service is done, always clean and grease the sliding mechanisms with a high-temp brake
grease to preserve the full range of travel. If not properly lubricated, calipers can lock in one position, resulting in only
one pad getting proper pressure on the rotor.
? Whenever possible, inspect the dust boots protecting the caliper piston and the two slide pins. These flexible covers
prevent dirt and moisture from fouling the action of the associated parts. Any damage or tears found in the boots must be
addressed quickly, before dirt and corrosion cause the parts to seize. It is possible to disassemble the caliper, clean the
parts and replace the boots if you have some skill as a DIYer. Labor charges, however, make this impractical in most auto
shop situations, so the most common resolution is full replacement of the caliper and bracket.
Regardless of the type of support, it is designed to have parts that withstand increased wear. The pads and discs we have
not considered because they are considered consumables. As for the support, the return movement of the piston is provided by
a rubber sleeve. When the driver depresses the brake pedal, the piston comes out of the body and deforms the
brake sleeve kit, when the pedal is released, the cuff tends to
present a starting position and drags the piston.
The brake system includes brake calipers, brake discs, brake pads(including brake pad fitting kits), steel pipes, brake fluid, etc. There are also
brake rubber dust cover kits.
- Created: 07-09-21
- Last Login: 07-09-21