A grinding noise when braking usually means the pads are worn through to their steel backing plates, which grinds against the rotor and damages it quickly. Other causes include a stone or debris caught between the rotor and dust shield, a bent dust shield, a sticking caliper, and rust on the rotors after the car has sat. Grinding when braking and turning can also come from a failing wheel bearing.
Causes
| Cause | Clues |
|---|---|
| Pads worn to the backing plate | Loud metallic grind, longer stops, scored rotors |
| Stone or debris | Sudden grinding or scraping from one wheel, may come and go |
| Bent dust shield | Scraping after brake or suspension work |
| Sticking caliper | Grinding and heat from one wheel, car pulls; see sticking brake caliper |
| Rust after sitting | Grinding on the first few stops that goes away |
| Wheel bearing | Grinding or growl that changes when turning; see wheel bearing noise |
Grinding but the pads are fine
If the pads have plenty of material, look for a stone wedged behind the rotor, a dust shield touching the rotor, a pad that has separated from its backing plate, or a worn wheel bearing. Removing the wheel and looking at both sides of the rotor usually finds it.
Grinding with new pads
New pads that grind may have been installed with the friction material facing the wrong way, may be the wrong pad for the caliper, or may be rubbing on rotors that were scored by the old pads and not replaced or resurfaced. Some low-grade pads with metal content also make a grinding sound until bedded in.
Grinding on one side
One-sided grinding points to that wheel: a worn or seized pad, a stuck caliper slide, debris, or a bearing. Uneven wear between sides often comes from a caliper that is not releasing; see car pulls when braking.
Is it safe to drive?
Metal-on-metal grinding reduces braking and destroys rotors, and can damage calipers. Have it checked as soon as possible and keep speed low. Rust grinding that disappears after a few stops is not a concern.
Repairs
- Replace pads in axle sets and replace or resurface the rotors if they are scored.
- Free or replace a sticking caliper and lubricate the slides.
- Bed in new pads; see brakes squeaking for the noise that follows a poor install.
For towing and heavy trucks, upgraded rotors and brake kits are covered in drilled vs slotted rotors, and pad life in how long brake pads last.
More guides: grinding noise when turning.
Shipping is a flat $80.00 per order to US addresses, with 15-day free returns. Questions? Ask a parts specialist.