What it does
The caliper is the clamp that squeezes the brake pads against the rotor. It uses a piston and slides on pins. If the piston or the pins seize up, the brake can stay partly on even when your foot is off the pedal.
Common symptoms
- The vehicle pulls to one side, especially when braking
- A burning smell from one wheel
- Smoke from a wheel after driving
- One wheel much hotter than the others
- One pad worn much thinner than the rest
- The vehicle feels like it's dragging, and gas mileage drops
- A soft or spongy pedal if the caliper is leaking
What to look for
- Heat check: after a drive, carefully hold your hand near each wheel without touching it. One that's much hotter than the others points to a dragging brake.
- Leaks: look for brake fluid around the caliper or on the inside of the wheel.
- Pad wear: uneven wear between the inner and outer pad on the same wheel often means the slide pins are sticking.
Could be something else
Pulling when braking can also be a collapsed brake hose. Pulling while just driving is more often alignment or tires.
Is it safe to drive?
No. A sticking caliper can overheat the brakes, warp the rotors and cut your stopping power. If a wheel is smoking, pull over and don't keep driving on it.
Related: Worn brake pads and rotors · Brakes squeaking or grinding?
Brake pulling or a hot wheel? Northwoods replaces calipers and does full brake service on site.