A brake caliper clamps the pads onto the rotor when you brake and releases them when you let off. When a caliper sticks - staying partly clamped - the brake drags constantly. That wastes fuel, cooks the pad and rotor, and can pull the car to one side. Here is how to spot it.
Symptoms of a sticking caliper
- Pulling to one side when braking, or even while driving straight.
- A hot wheel. After a short drive, one wheel is much hotter than the others, sometimes with a burning smell.
- Uneven pad wear. The pads on one wheel are far more worn than the other side.
- Reduced fuel economy or a car that feels like it is braking itself.
Common causes
- Seized slide pins. The caliper rides on greased pins. If they corrode or the grease dries out, the caliper cannot slide freely. A caliper guide pin kit renews them.
- A torn pin boot that let water and grit reach the pin. A pin boot kit reseals it.
- A sticking piston from corrosion or old fluid, which may need a caliper repair kit or a replacement caliper.
- A collapsed brake hose that traps pressure and keeps the caliper applied.
How it gets fixed
The fix depends on the cause: clean and re-grease or replace the slide pins, reseal or replace the boots, rebuild or replace the caliper, or replace a bad hose. Because a stuck caliper usually ruins the pad and often the rotor, plan on new brake pads and fresh hardware when you address it. Brakes are safety-critical - if you are unsure, have a professional handle it.