Technical > Wheels, Tyres and Brakes
XTR Brake Squeal
kwkirby01:
I've just had a new XTR front brake fitted onto my new Thorn rigid fork with rear facing brake bosses. The rim is a Mavic EX721 ceramic. The pads fitted to the brake are XTR non-ceramic (I think).
This replaced a suspension fork and disc brake combination. Fortunately when the bike was built I had the wheel built with a V-brake compatible rim rather than disc specific rim.
The problem is brake squeal - no need for any kind of a bell on this bike, just touch the front brake lever!
Some thoughts I've had:
1) The rims have done several hundred miles on the original disc brake, so there's probably a build up of gunk on the rim. Could this be the cause? Any ideas as to the best way of cleaning a ceramic rim?
2) Research suggests that XTR brake blocks are known for squealing. Should I try an alternative brake block?
Any help gratefully received.
Kevin Kirby
stutho:
I sympathise brake squeal can be a pain and XTC are known to be loud.
Try in order
* Scrub the rims with denatured alcohol (remove the tyres first)
* Also try Scrubbing with Muc-off - removes some things that alcohol can't!
* Check the mounting / pivot bolts are tight (8NM)
* Increase the toe in
* Put some talcum powder on the rim (I hear this can work but didn’t work for me)
* Try toe out, works for some (revert to toe in if unsuccessful)
* Try the left pad on the right and vice versa - expect very bad brake performance. (I don’t recommend this set up)
* Place two rubber washers either side of the pad spacers
* Switch to Cool Stop salmon pads - VERY good breaking but may still squeal
* Add a brake booster
* Switch to ceramic specific pad (green)- breaking will not be as good as salmons but is less likely to squeal
* Sell the XTRs on Ebay and get a pair of Avid Ultimate - the best rim brake bar none (allegedly) cost a packet and can still squeal!
* Buy earmuffs!
Personally I run with cool stop salmon on the front (facing backwards) with a brake booster on Mavic 727 ceramic rim using Ultimate callipers. On the rear I use Cool Stop green on 727, again with Avid Ultimate. I believe my braking is a good as I can make it (which was personally very important to me) and doesn’t squeal but did cost an arm and a leg to get right.
Good luck it can be a long process to get it right.
PS Has anyone got direct experience of both Ultimate and XTR or Arch Rivals? I was very tempted by Arch Rivals (being less than half the price of Ultimate) and have hear some good feed back about them. Anyway I made MY choice and am very happy with it.
kwkirby01:
Thans Stutho, I'll give these a try. Out of interest, where does one get denatured alcohol?
Kevin
stutho:
Denatured alcohol is Methalated spirit. You could also try isopropanol. Methalated spirit is avaliale in B&Q
lewisnoble:
Reviving this topic, which has been quiet for a while . . .
My problem is not so much brake squeal, but shudder. My raven Tour has ceramic rims, and XTR brakes, and even quite moderate braking causes judder / shudder in the forks; quite disconcerting and liable to induce a skid. My son's £290 Specialised, with cheapo V brakes, brakes better and more securely.
I have just put new pads on (KoolStop green), and it judders worse than ever. In fairness, I had better let them bed in before I try anything else, but if anyone has got any ideas . . .
I have increased the toe-in, which has helped a little, but the brakes are still unpleasant to use to stop quickly .
Lewis
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