There's more to your car's braking system than just pads and rotors. Nearly all modern cars use disc brakes on at least the front wheels, although four-wheel disc brakes systems are become increasingly common across a range of models. With disc brakes, your car's hydraulic braking system is used to ultimately compress a set of pads against a metal disc (the brake rotor) to create friction that will bring your car to a smooth stop. In this type of system, both the pads and the rotor are considered sacrificial parts that will eventually wear out and need to be replaced.
Of course, the pads and rotors are only the final piece of the puzzle. Your braking system also consists of a number of hydraulic components, including the brake caliper. Each wheel that uses disc brakes has a single brake caliper. The caliper's job is to act like a hydraulically actuated vise or clamp. When you press down on the brake pedal, the piston or pistons in each caliper push the brake pads against the brake rotor. At least, that's how the system works under ideal circumstances. In practice, calipers can sometimes fail.
The Causes of Caliper Failure
Since brake calipers are such simple devices, there are actually only a few potential points of failure. The most catastrophic is a loss of hydraulic pressure. Without hydraulic pressure, your brakes (at least on the affected wheel) will fail entirely. A total loss of pressure is often the result of a problem elsewhere in the braking system and it will rarely affect only a single wheel since usually each axle shares a single brake fluid "circuit." In some cases, the seals on a caliper may fail, resulting in a brake fluid leak at the caliper itself.
More commonly, calipers will "stick." This can actually have a number of causes. If the seals around the piston fail, it is possible for environmental contaminants to impede the ability of the piston to move freely. This can happen if dust and debris make their way into the piston chamber, but it can also be the result of the piston or chamber rusting due to water infiltration. Likewise, the slides that allow the brake pads to smoothly compress and release can become gummed up with debris or rust if their seals fail. These slides are lubricated as well, so damage to their seals can allow lubricant to escape.
Signs that Your Brake Calipers Have Failed
Any sudden loss of braking power is an emergency, and you should consult a professional immediately (and stop driving your car!) if it occurs. Luckily, most caliper failures are less dramatic.
If your caliper is sticking, it will most likely feel as though one wheel is "dragging" or as if your brakes are constantly engaged. This can sometimes result in your car pulling one direction, especially at low speeds. Brake calipers usually will not stick in the fully engaged position, meaning that at high speeds the relatively low amount of friction being created is overcome and you won't notice the problem quite as much. This is often coupled with an apparent reduction in braking power as the caliper will not fully engage.
If the problem is severe enough, this friction can actually generate a huge amount of heat and cause your brake pads to wear very rapidly. If you notice that one wheel has a suspiciously large amount of brake dust when compared to your other wheels, there's a very good chance that your caliper is sticking. Place your hand near the wheel (don't touch it immediately after driving – it may be very hot!) to see if there is an unusual amount of heat compared to your other wheels.
Dealing with a Bad Caliper
Fortunately, repairing a bad caliper is not usually an incredibly expensive job. Depending on the problem, it may be possible to rebuild your brake caliper instead of replacing it entirely. In some cases, however, it will be cheaper to simply replace the old part with a new one. The average cost of replacing a caliper is less than $300, with labor costs generally being under $100. This means that a rebuild over a repair can potentially save a large amount of money.
Whatever the case, never ignore a bad brake caliper. This is a central part of your vehicle's braking system and a vital safety component. Reach out to a company like Buettner Tire & Auto to learn more.