You touch your wheels after a drive and one is noticeably hotter than the rest - maybe with a faint burning smell. That is a classic sign of a dragging brake on that corner. It wastes fuel, wears parts fast, and should be fixed promptly. Here is what causes it.
What a hot wheel means
If one wheel runs much hotter, its brake is not fully releasing - the pad stays in contact with the rotor and generates heat as you drive. The heat is the symptom; the cause is something keeping that brake applied.
Common causes
- A sticking caliper piston that will not retract, often from corrosion or a torn dust boot - see the caliper piston guide.
- Seized caliper slide pins keeping a floating caliper from releasing - a guide pin kit renews them.
- Corroded hardware binding the pad in the bracket - see brake hardware corrosion.
- A collapsed brake hose acting like a one-way valve, letting pressure to the caliper but not back - see brake lines vs hoses.
- A seized parking brake cable on a rear wheel - see stuck parking brake.
Why you should not ignore it
A dragging brake overheats the pad, rotor, and fluid, can warp the rotor, kills fuel economy, and in extreme cases the heat can damage the wheel bearing or boil the fluid. It also usually gets worse. This overlaps with a sticking caliper.
What to do
Have that corner inspected: check the caliper, slide pins, hose, hardware, and (on the rear) the parking brake. Fix the cause, then replace the overheated pads and inspect the rotor - a badly cooked rotor often needs replacing. Fit fresh hardware. Brakes are safety-critical - if unsure, see a professional.