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I've had a bit of trouble with my front brake lately.. for some reason after I put a new pair of pads in, they work great, have loads of power and work as they should.
But after about 6 hours of riding they start squeeking (big time) and completely lose power, to the point where I couldn't stop to avoid horses and ended up crashing and rupturing a ligament!
So has anyone else had this problem or know anything about it?
Cheers
Could be pad contamination, any chance you got anything on them? Can be anything from oil to a sugary drink.
That's what I thought.. but I haven't got anything on them that I can think of. I've had to replace the front pads a bunch of times now because of it. Maybe I need to clean the disc surface? I'll give that a whirl.
Thoroughly sand the motor with some fine sandpaper, then clean thoroughly with meths. Then deglaze the pads with more fine grade paper. Then bad the pads in again. Lots of braking to a stop from 25mph to do it. A bleed wouldn't go amis either.
I had a very similar thing with my SLX brakes. I tried all the tips re deconatamination and I eventually traced it back to a leaking caliper which was contaminating the pads.
After some googling I found it was common problem and also that the piston seals are no replacable and you need to get a new caliper. Mine were 8 months old and are now in the hands of CRC/shimano waiting for some warranty action.
I have similar problems from time to time, I find that one of the pistons gets a bit lazy (mooves less/slower than the other)re centering seems to improve things for a time but the only real cure seems to be a good clean of the pistons and seals (in situ, nothing drastic)
That said, I stil find I change my pads before they are totally worn out as they tend to squeel more as they wear. The pads are cheap enough if you buy in bulk
Jonb has my money for his dianosis - thus why i wont be buying shimano brakes again !
2 sets of levers with deAd calipers - poor show from shimano
Ok i'll have a look and see if I can see any signs of leakage from the piston and go from there. Pads are cheap I admit but when you have to change them every couple of weeks then it becomes expensive!
Signs of leakage for me were very slight bubbling and hissing coming from around the piston when levers were pressed hard.
I was just about to say that sounds like you have a fluid leak in the caliper to me. Classic symptons, that is.........
Mines were squelching when you listened hard
Like someibe stepping into deep mud only really quietly 🙁
Had an M765 caliper do exactly that. Air was getting past the seal.
Just had a listen to my brake.. can't hear any squelching at all.. and it's never had any loss of firmness in the lever..
a mate has the same problem - the noise of the braking is incredible its gone past sqealling to just down right noise in general - i cant describe it, but it basially sounds like there are no pads in and metal on metal is braking - he has lost a lot of power to he says- ive told him to check the pistons- im sure as hes not touched them ONCE in well over a year that the pistons probably need a bit of TLC (cleaning, lubing etc) as one may well have seized etc..
I've cleaned my calliper up and lubed it to get it all moving smoothly before, and have still always had the same problem. Possibly a dodgy calliper from new?
Either way I think i'll have to replace the whole calliper if seals aren't replaceable.
Thanks for all your input everyone, much appreciated!
My XTs did this; I put it down to the seals going hard after being outside in the shed over two super cold winters. I could see bubbling if I looked closely while pulling the lever really hard, but they stayed firm throughout and never made any other noise (apart from the horrific SCREECH after the pads got too bad).
I changed the calipers, they've been fine since *touch wood*
Well today I stripped the calliper off the frame, took the pads out, sanded the crap off the pads, cleaned the rotor as good as I could with white spirit, andwiped the inside of the calliper out with tissue and white spirit.
I then noticed that there was a slight squelching sound when pulling the lever. But after putting it all back together again it still squeeled like a pig! So new pads went in and the squeeling stopped.
So hopefully with the new calliper fitted (on it's way!) and new pads, I should be squeek free at last!
Rotor + white spirit = contaminated pads.
Use meths or IPA to clean rotors. White spirit leaves an oily residue, which apparently burns off, but im not so sure.
Well I wiped and rinsed it off afterwards the best I could and it didn't seem to affect the pad when I tested it.
Hey ho they were old pads anyways, new ones on the way for the new calliper.