[Closed] Yet another case of BAD LOUD rotor squeal!

Tried a disc cleaning solution?

Threadlock on the bolts that hold the brakes to the fork / frame?

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I had a similar problem. I thought my rotors were clean. But a thorough wiping over with mentholated spirits completely fixed the squeal.

As above with rotor cleaning and also to ask if you've tried fitting softer compound pads? I.e resin / organic as opposed to sintered - which have bits of metal (AFAIK) in them.

Are the pads glazed?

Clean the discs, remove pads and give a light rub on fine sandpaper.

Commuting on the road every day? I've always suspected diesel-ey road-skank is the worst thing for disc brake performance/squeal. I'm sure mine used to suffer if my bike had been transported on the roof of my car in wet conditions when the rotors would get covered in spray from the road.

I now make sure I clean rotors with isopropanol after long roof journeys if it's been wet. I do it before i use the brakes to prevent any possible contamination of pads with skank. Has helped a lot I believe.

I wouldn't worry about sand. Anything adding to abrasion is going to help grind off any contamination rather than cause problems IMHO.

I had a similar problem with my XTs. No power, really yowly. Couldn't even do an endo with the back completely unweighted, they were that bad.

Tried a bunch of things, IPA (not the beer), sandpaper, heavy braking downhill. Took the bikes to Wales for a bit of xc poss trail centre riding, found myself on the bus at Arthur Stiniog, kicking myself that I'd never sorted the brakes out properly.

By the end of the second run they were sharp as hell again.

So I'd recommend some [i]really[/i] big hills, your local ones might not be big enough.

Don't know if you can burn the crap off on the oven instead?

It sounds as though the brake pads have gotten contaminated in my opinion. Do your rotors have a black appearance to them resembling an oily glaze?

Check for brake fluid leaks around the calliper etc. remove the pads and inspect for contamination. Try cleaning both the pads and rotor with brake cleaner/IPA as suggested.

Who's Arthur? 🙂

Antur.

Someone was recommending putting the discs in the dishwasher - heat & detergent apparently does a good job of getting contamination off.

I'd be wary of that. Ours won't run without rinse aid, and that leaves a slick residue on behind. Probably better to go for a dunk in boiling water, scrub with a clean brush and detergent, then rinse with more boiling.

I'd be wary of that. Ours won't run without rinse aid, and that leaves a slick residue on behind. Probably better to go for a dunk in boiling water, scrub with a clean brush (not one you've just washed your greasy frying pan up with!) and detergent, then rinse with more boiling.

fitted some s/h SLX brakes to my new build yesterday, came with sintered pads. Squealed like a banshee. I tried sanding the face off the sintered, gave the rotor a clean. Not benefit. I never use sintered normally anyway so I Swapped them out for some organics and bedded them in as usual and no problems. Inexpensive organics from SSC, Id rather have a spare in my pocket than put up with noisy sintereds for the extra life.

Yeah, plus what stoner said. BB7s on the cross type thing commuter were ridiculous with std Avid sintered. Hated the noise, but tried to convince myself it was a bell replacement safety feature.

Now on superstar organics, no noise except a meow if it's damp. 1/2 the life for <1/3 the cost.

OK, thanks for the ideas everyone. I have tried most of them, including cleaning with MUC OFF disc clean I use it after every few rides anyway), although cleaning discs again with meth spirits sounds like a good idea.

Cleaning my removed pads again, and this time also using a bit of sandpaper sounds worth a try too.

Someone (a bike shop that should know better!) suggested that I dab a bit of copper paste on the back face of the pads, to prevent mechanical resonance. I will never do that, because although it sounds like a good idea, such paste will contaminate everything and slowly creep everywhere! (Someone I know did this and learn from the mistake).

Softer Resin pads, yes I have used those before and yes both performance and quietness was very good, except I really do need to keep running sintered pads because: I am slightly big/heavy, plus often carry a modest weight on my back, plus it is winter, plus they last alot longer generally anyway. And also because: I have used Hope sintered pads before, without ANY problems.

Meth spirits and sandpaper it is then guys... thanks!
GBR.

Meth spirits

I thought the consensus was that meths left a greasy residue. Try and get hold of IPA/isopropanol/propan-2-ol. You should be able to source from a pharmacy or eBay.

Blow torch?

My previously silent brakes were putting in a performance worthy of Kate Bush on Tuesday night. I wonder if it is teh cold? It was at or below zero all night.

Never had a problem with Meths for cleaning the brakes........perhaps the greasy layer was left by using white spirit......you'd be surprised how many people use it thinking it's fine for cleaning all sorts of stuff 😆

you copper slip the rear of car pads. as long as its not every where I dont see the issue, silicone grease would be another option.

The Hope organic pads still last ages compared to most and are much less squeally than sintered.

Road oil and road salt will cause this.