Brake Pads and Discs: When to Replace Them

What your ears and eyes can tell you

Many pads have a small metal tab, known as a wear indicator, that touches the disc when the friction material gets low. It produces a high-pitched squeal when you are driving, and often goes quiet when you press the brake. A squeal is an early warning and it is sensible to book a check at that point.

A harsh grinding or scraping noise is more serious. It usually means the pad material has gone altogether and metal is rubbing on metal, which damages the disc and reduces braking performance. If you hear that, have the brakes inspected straight away and avoid unnecessary driving.

Pad thickness and what a garage measures

The real check is a measurement. With the wheels off, the thickness of the friction material is measured on each pad, and both inner and outer pads are looked at, because the inner one often wears faster. A garage will tell you if the pads are close to their minimum or will not last until the next service.

Pads can also wear unevenly, for example thicker at one end, or one side of the axle wearing faster than the other. Uneven wear usually points at a sticking caliper or a seized slider pin, so the pads are not the only thing to address.

• High-pitched squeal while driving: wear indicator or glazed pads
• Grinding or scraping: friction material gone, disc at risk
• Brake warning light on the dash: have it checked promptly
• Car drifting to one side when braking: uneven wear or a sticking caliper
• Longer stopping distances: do not wait, get it inspected

Discs: lips, scoring and warping

Discs wear too, and they have a minimum thickness set by the manufacturer. A raised lip around the outer edge of the disc, where the pad does not reach, suggests the disc has worn down and may be thin. Deep grooves or heavy rust pitting on the braking surface are other reasons to replace them.

A pulsing pedal or a shake through the steering wheel when braking is often described as warped discs. The usual explanation is uneven thickness or deposits on the disc surface. The vibration is felt when braking at speed. If the discs are within limits but unevenly worn, replacement is normally the sensible route.

Why axle sets matter

Brakes are replaced in axle sets, meaning both sides of the same axle at once. Changing only one side leaves the car pulling to the stronger side when you brake, which is unpredictable and unsafe. The same logic applies to pads and discs together: fitting new pads onto old, worn discs often gives poor results, with noise and reduced bedding in.

Front brakes usually do most of the stopping work, so they wear faster than the rear on many cars. That does not mean the rear can be forgotten. Rear pads, discs or drums can seize from lack of use, which is common on cars used mostly for short trips.

Brake fluid and getting them checked

Brake fluid absorbs moisture over time, which lowers its boiling point and can cause corrosion inside the system. Manufacturers specify a replacement interval, and it is worth following it. A spongy pedal or discoloured fluid can be signs that it is overdue.

At Banks of the Tyne in Hebburn we handle brake pads, brake discs and wider brake repairs, and we will show you the measurements and explain why a part needs replacing. Winter road salt and wet weather on Tyneside can speed up corrosion, so it is worth having them looked at before the cold months. Cost depends on the vehicle and which parts are needed.

Frequently asked questions