Shimano Disc Brakes Squeal and dont work.

robbolevens
robbolevens Posts: 2
edited August 2015 in MTB workshop & tech
For a while my rear brake has been ineffective. I originally thought it was contaminated either the pads or the discs.

Basically the lever has the be pulled all the way back to the bars to make anything work. But at the start of a ride they squeal a lot. Usually by the end of a long downhill if I have had the brake on all the way down it will start working effectively but then when I start my next ride its back to being ineffective and squeals.

I have replaced pads, rotors and bled the system twice. I have even cleaned both the pads and discs with brake cleaner and sanded down rotors and pads.

Even after bleeding the system the lever can be pulled all the way back to the bars. The front lever bites almost immediately.

My next step was to replace the levers and caliper? Anyone else got any ideas?

This is the system I have:
Shimano A-M506, Hydr. Disc Brake (180/160)

Comments

  • nicklouse
    nicklouse Posts: 50,675
    Sounds like many things.

    You are not bleeding the rear brake correctly. The caliper is not aligned correctly and you are glazing your pads.

    I would have then sorted correctly.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • The Rookie
    The Rookie Posts: 27,812
    If you keep glazing the pads, get some different ones!

    As for lever coming back to the bars, well that could be bleeding or the fact you keep pushing the pistons back to take the pads out and them taking a while to settle.
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.

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