Brake problem

That's 56,000 miles in real money. Time to change the pads (maybe the discs too). There are usually anti-squeal shims at the back of the brake pads-just a piece of thin springy metal. Make sure they're fitted and put a smear of grease on them. I'd service the auto transmission as per the book. DaveK.

Thanks Dave. Will check it out. Had front pads changed 20000kms, oh sorry......12427.4 miles ago in real money ;-P , but I think it is the rear that produces noise. Anyway, going to get a second opinion from another mechanic if that's what it takes.

There's a bit of squeal at the start said your mechanic? He may have fitted new pads or discs or both. Did he?

no, he didn't do anything. I asked him to check out the brakes because of the squeal I was hearing and he said it was fine when I picked the car up. I am guessing someone took it for a test drive and heard very little.....but that's the whole point. They wouldn't have heard very much if the test drive only went around the block once or twice. Once the brakes, front or back I am not sure which, have been used a reasonable amount in stop start traffic or down hills, that's when the squealing starts and it present with light to moderate brake pressure but not when applying them harder. Does that shed any more light on it? Cheers, Jasen

I never did get my head around how those anti squeal shims did their job. As I recal they were sandwiched between the caliper pistons and the back of the brake pads. I know they do the job, BUT HOW?

If some kind person has the real answer, it would cure 20 years of curiousity.

Rdgs Bucket

Don't know how they work, but you can get a pink rubbery liquids to squirt on the pad to do the same thing. Don't know haw that works either.

Presumably the squealing is caused by vibration induced in the pad causing it to move backwards and forwards quickly. The methods used to minimise this are based on either damping the vibration with a spring, or providing less frictional resistance to the things around the pad that it is in contact with.

Chris

(Top posting corrected)

a.n.other wrote:

Presumably in the same way that applying a high temperature grease (eg Copaslip) or using the self-adhesive anti-squeal tape does. It allows the vibration-induced movement, but limits the ability of that movement to create the sound.

Imagine the screech that scraping your finger nails down a blackboard makes. Now put something slippery in between and it won't make a sound.

Chris

Thanks for that

I think I get it now???

I had thought the pad was fixed ridgidly as far as side to side and up and down motion were concerned, but now realise there must be a tiny amount of movement on the pins its secured with (hole clearances around pins must allow a tiny bit of movement). I suppose there is very fast miniscule movement from the pad and the back of the pad rubs against the piston. I can now see how the shim stops this rubbing and the squeeling noise.

Thanks guys Bucket