Brakes squealing or grinding: what the noise means

What the noise actually means

Most pads carry a built-in wear indicator that contacts the rotor and squeals once the friction material reaches a minimum thickness. That sound is intentional.

If the warning is ignored, the pads can wear down to bare metal and the backing plate grinds directly against the rotor. That is where grooves and scoring come from.

How brake pads are meant to wear

Brake pads are a wear item by design. Their friction material wears down gradually so that the rotor underneath, the disc the pads clamp onto, does not.

Common causes

• The pad wear indicator, heard as a consistent high-pitched squeal
• Pad material worn away, heard as grinding or metal on metal
• Semi-metallic pads, which can be noisier than ceramic or organic ones
• ABS working under hard braking, which can grind or click and is normal

What to do now

1. Note whether it is a squeal or a grind, and whether it happens every time you brake or only now and then.
2. Look at the pad thickness through the wheel spokes if you can see it.
3. Check the brake fluid level against the min and max markings. A dropping level can mean worn pads, or a leak.
4. If it squeals every time, book a pad check soon rather than waiting for grinding.
5. If it grinds, get it checked immediately, and ask for the rotors to be checked as well as the pads.
6. On an electric car, look at the disc face, not just the pads.

Squeal, grind, or something normal?

• A consistent high-pitched squeal every time you brake: usually the pad wear indicator, have the pads checked soon.
• Grinding or metal on metal: pad material likely gone, get it checked immediately.
• Grinding or clicking with a pulsing pedal under hard braking: ABS working, which is normal.
• A pulse or vibration in the pedal during normal braking: usually uneven rotor thickness, not the pads.
• Electric car, low pad wear but rough braking: rusted or scaled discs from regenerative braking.

What people often get wrong

That a squeal can be ignored because it comes and goes, or because the pedal still feels normal. Once the pads are low, the wear indicator is designed to be heard consistently, and waiting risks grinding and damage to the rotor.

When the car must go to a workshop

Grinding or a metal on metal sound should be checked immediately. Replacing pads and rotors is a job for a professional, because torque specs and proper seating matter for safety.

Read next

• Brake pad wear light: how long can you wait?
• Soft or spongy brake pedal: why it is urgent
• Car shakes when braking: this is the usual cause

This page is general information and does not replace a professional assessment. Symbols, codes and behaviour vary between makes. Always check the handbook for your own car.