Squealing brakes : Not Again!

olivier renault · 2 Sep 2014 at 15:15

Heyup chaps,

There's something wrong with my bike brakes, I can't get rid of the squealing. I've been to a couple of bike shops, but they've been mostly useless. Just spray some weird crap on them and call it a job done.

This usually happens when I leave my bike alone for a while. No brake bite, loud squeal, then I have to pour a bit of water on the calipers, and they work fine. That usually lasts 10, 15 mins before they start slipping and squealing again. It's a Specialised, with some basic Shimano discs.

1) I've clean them up good a few times. Basic hot water+soap clean, a good rinse, then using break cleaner to scrub the pads and discs.
2) I've 'bedded' the brakes. They bite fine when they have a bit of water on them.
3) I haven't noticed any oil leak, and I have good brake pressure.

Am I destined to keep a bottle of water at all times to keep those damn brakes working? Is this something to do with the environment (city polution)?

Supercow · 2 Sep 2014 at 15:55

Have you tried some GT85 on your brakepads?

FrenchTart · 2 Sep 2014 at 15:57

Don't put GT85 on your brake pads. Not unless you like having no ability to brake.

Supercow · 2 Sep 2014 at 15:58

It will stop the squeal though

FrenchTart · 2 Sep 2014 at 15:58

That is very true

Begbie · 2 Sep 2014 at 21:31

What brakes are they?

Assume hydraulic? Changed pads? Personally wouldn't care about the squealing all that much as long as they work.

NoNameNoNumber · 2 Sep 2014 at 21:32

Sand a chamfer on the leading edge of the pads.

olivier renault · 3 Sep 2014 at 13:18

Begbie said:
What brakes are they?

Assume hydraulic? Changed pads? Personally wouldn't care about the squealing all that much as long as they work.

Yeah, hydraulic, resin pads, steel disk. I've changed the pads, tey are brand new. I've cleaned the old ones, same issue. I've try the sanding as well.

I think they are contaminated. When left alone for too long, the brakes get very, very slippery (until I do the water squirt maneuver). Must be hydraulic fluid seeping through, even though I'm not loosing brake pressure

Back to the shop (still under warranty), and no BS this time.

touch · 3 Sep 2014 at 16:20

olivier renault said:
Must be hydraulic fluid seeping through, even though I'm not loosing brake pressure Back to the shop (still under warranty), and no BS this time.

A very small leak wont immediately lose brake pressure, it'll just let some more fluid from the reservoir into the system. Eventually the reservoir will empty and you'll start to lose pressure.

"andy" · 6 Sep 2014 at 21:01

squeeling is vibration , if you have had the caliper off to change pads recently then check its all lined up as best as it can. could dab of copperslip behind the pads

even if your leaking fluid it wont seep through the metal backing of the pad onto the pad

arknor · 8 Sep 2014 at 17:22

stick the pads in the oven to burn off any oil residue etc, I think you can do it on a hob too, not sure you would have to google