Brake pads and discs: signs they need replacing

How brakes work, in brief#

When you press the pedal, the brake fluid carries the pressure to the callipers, which squeeze the pads against the disc that turns with the wheel. The friction slows the car. Pads have a layer of friction material that gets thinner with every stop; the disc wears too, more slowly. On some cars the rear wheels have drum brakes with shoes, which work on the same principle.

The brakes are the car's most important safety system. Any of the signs below is worth a check by a mechanic, not a wait until the next service.

Signs the pads or discs are worn#

• A high-pitched squeal when braking: many pads have a metal wear indicator that touches the disc once the friction material is thin, precisely to warn you.
• A harsh metallic grinding: a sign the pad may be worn through and metal is rubbing the disc. Get to a garage as soon as you can: the disc is quickly ruined this way.
• Vibration in the steering wheel or the pedal when braking, especially from speed: usually warped or unevenly worn discs.
• The car pulls to one side under braking: one brake is working harder or weaker than the other, for example a sticking calliper.
• A soft, spongy pedal or one that sinks a long way: possibly air or moisture in the brake fluid, a leak, or very worn pads. This is a serious sign.
• The brake or pad-wear warning light on the dashboard: on many cars a sensor reports worn pads. Check the manual for what your light means.
• Longer stopping distances, or you have to press harder than before. Worn suspension lengthens them too.
• A raised lip around the disc and deep grooves on its surface, which you can sometimes see through the wheel spokes.

How long pads and discs last#

There's no mileage that fits everyone. Wear depends on the car, the parts, the roads and above all on how you drive: city traffic with frequent stops and mountain roads use up brakes faster than motorways. What matters is the thickness left:

• Pads are measured at every service; the mechanic tells you how much material is left and when to come back.
• Discs have a minimum thickness set by the manufacturer, usually marked on the disc. Below it the disc is replaced, even if it looks fine.
• New pads on worn discs don't bed in properly and brake less well; the mechanic tells you whether the discs can stay.

Checking the brakes is part of a car service, so an attentive mechanic will tell you in good time that a change is coming up.

Why both wheels on an axle are done together#

Pads and discs are replaced per axle: both front wheels or both rear wheels, even if only one looks worn. If one side brakes with new parts and the other with old ones, the braking force differs left to right, and the car can pull to one side just when you brake hard. If one wheel wears much faster than the other, ask why: a sticking calliper or a seized guide pin.

Brake fluid: why it gets changed#

Brake fluid slowly absorbs moisture from the air. The more water it holds, the more easily it boils during long or repeated braking, and the pedal can go soft just when you need it. That's why the manufacturer sets a replacement interval, usually in years, which you'll find in the service book.

• The level drops slightly, and normally, as the pads wear. A sudden drop may mean a leak.
• Don't top up with just anything: use the fluid type printed on the reservoir cap or in the manual.
• A test at the garage shows how much water the fluid has absorbed.

When to stop driving the car#

If the pedal goes to the floor, the red brake warning light comes on or the car brakes noticeably less well, stop safely and don't carry on. Call roadside assistance or a tow truck to get to a garage.

Brakes are also checked at the ITP (Romania's periodic roadworthiness test) on a brake tester, together with the parking brake, the lines and the pedal; a major or dangerous fault means a fail. See what is checked at the ITP.

What to ask the garage#

1. What needs replacing: just the pads or the discs too, front or rear, and why.
2. How much material is left on the pads and how thick the discs are compared with the manufacturer's minimum.
3. Which parts they fit: original or equivalent, and from which maker.
4. Whether they also check the callipers, the guide pins and the condition of the brake fluid.
5. How to drive for the first few kilometres after the change, so the new pads bed in.
6. What warranty they give on parts and labour (see what a repair warranty covers).

How CariX helps#

In the free driver account you keep your car and the work done on it in one place.

• "Is the price fair?" shows an indicative price range for brake work in your city, from the prices garages list on CariX on their pages and quotes; the real price depends on the car and the parts.
• Warranties: if the garage records a warranty on the job line, in months or kilometres, you see it under "Active warranties" on the car and get an email 30 days before it ends (for a warranty in months).
• Your own reminders: you can add a reminder yourself, for example for the brake fluid change at the date in the service book, and get it by email.
• The car passport keeps the jobs recorded by garages, with the mileage they confirmed.