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squeaky brake

1125 Views 3 Replies 3 Participants Last post by  TheBossOfBread
I've a br-m8020 caliper with H03A pads in. I just replaced the pads. I went downhill (snow, 1100m decent) and all was fine. When I came to the bike after few days my front brake was squeaking a lot. But what is worse - it was not braking properly either. I tried to "warm the brake up", did quite few of accelerations-brakings without any luck.

I checked the caliper - there's no braking fluid leaking anywhere.

I took the snow and threw it on caliper - the squeak stopped and brake was working ok again. I did few accelerations-brakings again and it was ok. Maybe pads are still wet?

What I don't understand is why is this happening. Squeak is one thing but loosing braking power is the other.
Right now I'm waiting for pads to dry out and will try it again. But I'm curious to know if somebody else had similar experience.
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take pads off....cover them in rubbing generous....then light on fire for a minute ....after it cools...take some sand paper put it on the ground. Then take pads do figure 8's on sand paper ...keeping pad flush and even to the same thing to the rotors....but just use a sanding block and rough up rotors
When I wrote the question I had still my old pads. As nobody replied I didn't update this thread. Thanks for your reply.

In the mean time I did this: left them in alcohol (isopropyl) for 2 days, sanded them down, baked them in the oven for few minutes, cleaned the rotors, checked that rotor is not bent, double-checked I don't have leaks from caliper. Nothing helped. I bought new pairs, front and rear. Did a proper break-in procedure, went for a down hill ride (~1100m/3600feet vertical descent). All OK.

I keep my bike in a cellar (I'm at new place now), around 3C/37F temperature, moist. For a day or two it's all OK, then pads squeal/squeak even on a bike stand with very little pressure applied. And it's not just this bike, even my new bike is doing the same.

In the mean time I did the same descents 3 times. When I start the descent my brakes are weak and make terrible noise. When I throw snow at caliper few times my brakes start to work - aggressive bite is back and no squeak.

I don't understand this. It seems like maybe some sort of weird layer is formed on pads or rotor preventing brakes to work properly ? Water/snow works like magic here..
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This is unfortunately a "feature" of shimano brakes. During being sat they spit a tiny mist of brake fluid on the pads/rotor, which is why they squeal and seem to fix themselves with snow/water.
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