Grinding noise when braking
A metallic grinding when the pedal is pressed almost always means the friction material is gone and the pad backing plate is running directly on the disc, or something hard is trapped between pad and disc. A continuous grind that also occurs without braking points to a seized caliper, a dragging pad or a failed wheel bearing instead. Do not keep driving on a metal-to-metal pad: the disc is being destroyed and braking distance increases sharply, especially when hot.
Urgency
Stop driving
Possible causes, most likely first
- Brake pads worn to the backing plate
Harsh grinding on every stop, deep circular scoring on the disc and metallic dust on the wheel. Look through the wheel: less than 2-3 mm of friction material or a metal-on-metal shine on the disc means immediate pad and usually disc replacement. - Stone or debris trapped between pad and disc
Sudden grinding that started while driving on gravel or after a road repair, often disappears after reversing a few metres. Remove the wheel and inspect the gap between pad and disc and the inside of the dust shield. - Seized caliper piston or slide pins
Grinding that continues after the pedal is released, a hot wheel after driving and a car pulling to one side. Check that the piston pushes back with a clamp and that the slide pins move freely; replace the seals or the caliper if corroded. - Severely corroded disc after long standing
Rough grinding on the first few stops after the car has stood for weeks, improving as the rust wears off. If the surface does not clean up after 20-30 stops or the disc has deep pitting at the outer edge, replace it. - Worn or collapsed wheel bearing
Grinding or rumbling that is present all the time but changes pitch under braking or in corners. Lift the wheel, spin it by hand and listen for roughness; check for play at 12 and 6 o'clock. - Broken pad retaining spring or anti-rattle clip
Loose pad shifts and catches the disc edge, producing an intermittent grind or clunk under light braking. Remove the caliper and check that the pads sit square in the carrier with all hardware present. - Bent or loose dust shield or backing plate
Light tinny scraping that may come and go with speed, sometimes caused by a kerb strike or recent work. Bend the shield away from the disc by hand and recheck.
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What you can check yourself
- Look through the wheel spokes at the pad thickness and the disc surface for deep grooves or a bright metal ring.
- Check whether the grinding happens only when braking or all the time (bearing or seized caliper).
- Try reversing slowly and braking a few times - a trapped stone often clears this way.
- Compare wheel temperatures after a drive; a hot wheel with the noise points to a seized caliper.