Longer stops, a soft pedal or a pull to one side? Park it
Grinding plus any change in how the car stops means the brakes themselves are affected. Pull over somewhere safe, switch off and arrange a tow or a mobile mechanic. RACV says to have a grinding noise looked at as soon as possible, and RAC WA points out that driving with faulty brakes is illegal as well as dangerous. If anyone is hurt or in danger, call 000.
Is it really grinding?
| What's usually happening | What to do | |
|---|---|---|
| A high squeal as you brake | A small metal tab on the pad saying it's nearly worn out (RAC WA) | See a mechanic soon. See squealing brakes |
| A light scrape on the first few stops of the day | Surface rust on the discs after rain or a wash, which the pads wipe away | Nothing, if it's gone within a few stops |
| A steady scrape from one wheel, even off the brakes | Often a stone caught behind the disc, or a bent dust shield | Have it checked this week, because it can score the disc |
| A deep grind you can feel through the pedal | Pads down to the metal | Leave the car parked if stopping has changed. Send the job today |
| A grind or whirr from under the car, not linked to braking | NRMA lists the differential or gearbox low on oil, a universal or CV joint, or a wheel bearing | Have it looked at soon |
| A rapid buzz and a pulsing pedal in a hard stop | The ABS (anti-lock brakes) doing its job | Nothing. That's normal |
Why does it go downhill so quickly?
A brake pad is a layer of friction material bonded to a steel plate. When that layer has gone, steel is pressing on the disc. Stopping power drops, the disc gets scored and the heat goes up.
Every stop adds to the damage. What might have been a set of pads becomes pads and discs, and a pad worn right through can let the caliper piston (the part that pushes the pad) travel too far and leak. RAC WA adds that worn pads and discs can wear unevenly and set up a vibration, which is when you'll feel the car shaking under braking.
What to do today
Work out which end and which side
Listen with the radio off and the windows down on a quiet street. Front or rear, left or right, is useful to the mechanic.
Think about how the car's been stopping
Is the pedal lower or softer than it was? Does the car pull to one side? Can you smell anything hot?
Have a look without touching
Through the wheel spokes you may be able to see the outer pad. If there's almost nothing between the metal plate and the disc, that's your answer. Brakes get very hot, so keep your hands off them.
Keep the driving to a minimum
RAC WA's advice is to drive or tow the car to a mechanic for urgent diagnosis and repair. Drive it only if it's stopping normally, gently, on quiet roads and straight there. If you're in doubt, ask for someone to come to you.
What will the mechanic measure?
With the wheels off, they'll measure what's left of the pads and the thickness of the discs. Each disc has a minimum thickness set by the maker, and one that's scored or thin has to be dealt with.
They should also find out why it wore out. One pad far thinner than its partner on the same wheel can mean a sticking caliper or slide pin, and new pads won't last if that stays. They'll check the brake fluid and the other axle while they're there.
Any mechanic who does regular brake work can handle this. If you tow, carry heavy loads or drive a 4WD, say so, because it affects the choice of pads.
What a good estimate should spell out
- Which axle, and whether it's pads alone or pads and discs.
- What the discs measured, against the maker's minimum.
- Whether the calipers and slide pins are sound.
- The condition of the brake fluid.
- What happens to the old parts, if you'd like to see them.
What's yours, and what isn't
You can
- Note when the noise happens, and from which corner.
- Look through the wheel at the outer pad without touching it.
- Check the brake fluid level on flat ground, with the cap on.
- Keep the car off the road if stopping feels different.
Leave to the mechanic
- All brake work: pads, discs, calipers and fluid.
- Measuring pads and discs against the maker's limits.
- Finding out why one wheel wore faster.
- Testing the brakes before the car goes back on the road.
In your shoes
We'd send the job today. If the car still stops straight and the pedal feels normal, we'd drive it gently to the mechanic and nowhere else. If anything about the stopping has changed, we'd leave it parked and put in the note that it needs a mobile mechanic or a tow. The sooner someone looks at it, the more likely it is to stay a small job.