Why do car brakes squeak?

[wilsarnie]

Just generally.

And they why do they squeak for a while and then stop over time? If it was something to do with the shoes/pads/drums then you'd think it'd get worse as opposed to just stopping.

[Andyvon]

Is the noise bad wilsarnie? Are they just squeaking or squealing and is the noise from the front or back? Your brakes shouldn't make any noise at all but there can be a number of reason for them doing so.

The front brakes are usually a couple of pads that grip a metal disc that turns with the wheel. When they press against the disc the friction slows the car (in the same way as if you grip a vinyl record between your finger and thumb as it turns). The pads self-adjust with wear and they have springs to stop any squeaks or squeals. If the little springs are missing (often because someone couldn't be bothered to fit new ones) then the pads are slightly loose and they can make a noise.
If your pads are worn down to their backing that can make a very bad noise like a shriek or grinding. The same with the drum shoes at the rear.

Without knowing exactly what the noise is or where it is coming from, it's hard to say much more. There probably isn't a great deal wrong with your brakes but I would suggest you have your brake pads checked or changed. They are only cheap and make sure they have new anti-squeal springs. Noise can also come from the brake discs if they are worn and the new pads before they have bedded in.

. Hope that helps.

[wilsarnie]

Thanks Andyvon, very comprehensive answer.

Mine are just squeaking from the front but only a little. I've heard it could be brake dust. The only reason I was asking is because they used to squeak, and then they stopped for months and now they start again and am just wondering why they would do that. They're definitely not grinding, have had that before and it was terrible!

I'm currently doing a MVE Womens course so have planned to take my wheels off to look at my brakes this weekend, get a bit of practice in!

It's been about 18 months since I had all of the pads done so I'll defintely have a look.

[homer75]

Take the pads out and smear a SMALL amount of copper grease ( CopperEase ) on the backs of them - that will cure your squeaking. Be careful not to get any on the braking surfaces of the pads or on the discs.

[Toureman]

The brake pads squeal because the Pads vibrate against the caliper's pistons when you brake.

They can stop squealing over time as dust colllects in the very slight gap between the pads and calipers pistons so stopping the vibration.

Perhaps rain could wash out some of the dust and they will start squealing again.

As Homer says a little lubrication, but only with Copaslip or Copperease which is a high temprature grease applied very sparingly on the back of the pads will stop any squeal.

Lubricate anything and it will be quiet.