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  1. #1
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    Best sanding paper grit - disc brake pads cleaning

    Hi everyone,

    I just bought a used bike and it came with M785 Xt disc brakes and although the pads are not new there's maybe a couple 100km left in them. The only problem so far is that the brakes a squealing quite a bit, and I suspect they might be dirty.

    I have a couple of questions.

    First, is it ok to clean the pads with either alcohol or commercial brake cleaner (which one would work best ?)

    Secondly, I've read that sanding the brake pads could also help, what grit sandpaper should I use for this process ?

    Thanks for your answers !

    Cheers!

  2. #2
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    I always use 90% isopropyl alcohol. (Seems to work better then the 70% stuff)

    The grit I use 60 or 80 medium works good for me.

    100 already seems to fine.

    After you are done sanding clean the pads with 90% ipa.

    Make sure you do a proper brake in after cleaning brake parts.

  3. #3
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    try using a flat file instead as it won't transfer any of the adhesive compound to the pads like sandpaper or emory cloth will.

  4. #4
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    ^^needs to buy better quality sanding paper.

  5. #5
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    Quote Originally Posted by Learux View Post
    Make sure you do a proper brake in after cleaning brake parts.
    What do you mean by that exactly ?

    Thanks !

  6. #6
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    Brake in is required after cleaning rotors and pads. Its purpose is to get an even layer of brake material on the rotor.

    There is many tutorials on the internet.

    I do about 15 slowdowns from 20 to 10 mph, with enough time in between to cool the rotor.
    Drag my brake for a bit and this always works good.

    Most important is not to come to a full stop when doing this. This will build up an uneven surface and creates problems. (noise,etc)

  7. #7
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    Quote Originally Posted by Learux View Post
    Brake in is required after cleaning rotors and pads. Its purpose is to get an even layer of brake material on the rotor.

    There is many tutorials on the internet.

    I do about 15 slowdowns from 20 to 10 mph, with enough time in between to cool the rotor.
    Drag my brake for a bit and this always works good.

    Most important is not to come to a full stop when doing this. This will build up an uneven surface and creates problems. (noise,etc)

    Thanks that helps a lot ! I will try that tonight, hopefully cleaning up the pads and the rotor, with the break in will make a for a quieter brake.

  8. #8
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    Quote Originally Posted by Learux View Post
    ^^needs to buy better quality sanding paper.
    naaaaa thanks though the file is a far superior option.

  9. #9
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    My brakes were hopeless and had notice gaze, until I took to the disks with a paint stripper wheel on a grinder. Now they will stop sooo quickly. I have the OTB bruises to prove it.

    Also Used a file to skim the pads.

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