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I'm running XTR trail brakes with XTR rotors and have been through 2 sets of pads and the third are now also making the most incredible howl after minimal use.
Having tried changing the pads and getting the rotors warm and then cleaning them with disc brake cleaner, on the weekend I zip-tied the levers to the bars with kitchen paper wedged between the pistons and left them overnight, there's no oil on the paper so why are they making this unholy racket?
Help please.
I thought this was going to be a thread about some mountain biking blues singer!
Seriously though folks...it can just be down to the caplipers not sitting squarely over the rotors. slcacken the mnount nuts, pull on the brake, re-tighten.
If you are using IS mounts, it often helps if these are faced with a cutting tool to ensure the caliper can sit squarely.
Is it just noise or are they lacking power, any excessive play in levers?
IME brake cleaner [s]doesn't always[/s] hardly ever cuts the mustard, try wet and dry and soapy water on the disks, obviously you will need to bed them in again.
Thanks dirtydog, I was just about to say, they lack power too. no excessive play that I've noticed.
Copperslip under the pads has helped me in the past.
So it does sound like contamination, possible cross contamination from discs.
Do they do howl all the time or is it just when they get wet?
If they needed bleeding you'd be getting exessive travel at the lever, if the levers are firm and you lack power it would tend to suggest contamination.
What's the best way to thoroughly clean the rotors if cleaner hasn't worked?
Washing up liquid, hot water and some 400 wet and dry IME.
Brake cleaner won't get rid of baked on grime, in fact I can't remember a single case where its actually worked.
slcacken the mnount nuts, pull on the brake, re-tighten.
I wouldnt recommend this, as it only works if both pistons move the same amount at the same time. You tend to find there is a "lead" piston which moves first and thus buggers it up!
Far better to do it by eye.
You could stick the rotors in a pan and boil them for a bit. You should see any oil float on the top. Refit them then find your nearest steep long hill and bed the pads in.
What about a kerosene parts wash?