Brakes tend to give you plenty of warning before they need attention. The trick is knowing what the signs mean, and whether you're looking at a quick pad change or new discs as well.
Here's how to tell when your brake pads and discs are worn, how to check them yourself, and what affects the cost of replacing them.
How discs and pads work together
When you press the brake pedal, a caliper squeezes two brake pads against a metal disc that spins with the wheel. The friction slows the car down. Both parts wear a little every time you brake, but pads wear much faster than discs, so you'll usually replace pads two or three times for every set of discs. How often depends a lot on how and where you drive. Lots of town driving and heavy braking wear them faster than long, steady motorway runs.
Signs your brakes need attention
Squealing or squeaking
Many brake pads have a small metal tab, called a wear indicator, that squeals against the disc when the pad gets thin. A high-pitched squeal that comes and goes with the brake pedal is a common early warning.
Not every squeak means worn pads, though. A bit of noise on a damp morning is often just surface rust on the discs, and it should clear after a few stops.
Grinding
A harsh grinding or scraping noise is more serious. It can mean the pad material has worn right down and metal is rubbing on metal. If you hear this, get the brakes checked as soon as possible. Grinding pads damage the disc quickly, which turns a pad change into a disc and pad job.
A warning light
Many cars have electronic wear sensors in the pads. When the pads get low, a light comes on in the dashboard. If your car has these, you'll usually need to replace the sensor along with the pads.
Vibration or juddering
If the steering wheel or brake pedal shakes when you brake, especially from higher speeds, the discs may be unevenly worn or warped. That usually means new discs.
Pulling to one side
If the car pulls left or right when you brake, one side is braking harder than the other. That can be uneven pad wear, a sticking caliper, or a problem with a brake hose. It needs checking promptly.
A longer stopping distance
If the pedal feels softer, travels further, or the car takes longer to stop, get it looked at straight away. That can point to worn pads, but also to a problem with the brake fluid or hydraulics.
How to check your brake pads
On many cars with alloy wheels, you can see the pads through the gaps in the wheel. Look at the caliper, then at the edge of the pad pressed against the disc. You'll see a metal backing plate with a layer of friction material on it.
As a rough guide, most manufacturers recommend replacing pads when the friction material gets down to about 3mm. If it looks thinner than the backing plate, it's time to replace them. Check the inner pad as well if you can. It sometimes wears faster than the outer one, and you can't always see it without taking the wheel off.
How to check your brake discs
Look at the face of the disc through the wheel. A healthy disc is smooth and fairly even. Things to watch for:
- A raised lip around the outer edge, which shows how much the disc has worn
- Deep grooves or scoring
- Blue or dark heat marks
- Cracks, especially around the holes on drilled discs
- Heavy rust on the braking surface, which can happen if a car has been parked up for a long time
Every disc has a minimum thickness, usually stamped on the disc itself. A garage can measure it for you with a micrometer.
Do you need discs as well as pads?
Not always. If the discs are smooth and above their minimum thickness, new pads are often enough. But if the discs are badly worn, scored or vibrating, it makes sense to replace both together. New pads on worn discs won't bed in properly, and they won't last as long.
Always replace discs and pads in pairs across the same axle, so both front wheels or both rear wheels. That keeps the braking even from side to side.
What affects the cost?
The price of a brake job depends on a few things:
- Pads only, or discs and pads together
- Front or rear axle. Front brakes do most of the work, so they're often larger.
- Your car. Larger and performance cars usually have bigger, more expensive discs.
- Extras such as wear sensors, or calipers if one is sticking
- Labour, if you have it fitted by a garage
Buying the parts yourself and having a local garage fit them is often cheaper than a fixed-price brake deal, and it means you know exactly what's going on the car.
Finding the right parts
Brake discs and pads are specific to the model, the engine and sometimes the trim, because some versions of the same car have bigger brakes. The safest way to get the right parts is to match the part number on your old discs or pads, or the OEM number for your car. If you're not sure, send us your VIN and we'll help you find the right ones.
We stock a wide range of brake discs, pads, calipers and sensors for most popular makes.
This article is a general guide only. Brakes are a safety-critical system. If you're not confident working on them, have them checked and fitted by a qualified mechanic.