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I have a shimano br-m446 installed in my MTB, i recently replaced it with new pads, my problem is that it is squealing so bad, with a mild to moderate vibration during braking in downhills. and it's really really annoying.

I haven't placed anything on them, i clean my rotors with water and laundry detergent i don't know if that causes the problem.

if so what should i do?


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Did you follow the burn in procedure?… – alex Sep 10 '13 at 2:04
the document doesn't seem to load – Juvil Sep 10 '13 at 3:00
but it does sounded that i needed that. i knew about the bedding, didn't know you had to do it every replacement -.- silly me. thanks tho. – Juvil Sep 10 '13 at 3:07
Try this link:… – alex Sep 10 '13 at 3:47
Did your first set of pads have this problem at any time? – joelmdev Sep 12 '13 at 22:12

As suggested in the comments, follow the burn in procedure. If that fails, then you can try to reset the caliper alignment (follow the installation instructions or one of the many sites on the internet). Also clean the disc with a volatile oil solvent such as alcohol or methylated spirits.

If that fails, it may be your pads - what did you have and what did you replace them with? Organics tend to make less noise but don't perform as well or last as long, metallic compounds tend to be better performing material and last longer but are more prone to noise.

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Could also try sanding the pads if there's any contaminants on them. – Aaron Sep 10 '13 at 14:17
I did reset the alignment but it still vibrates, it's a replacement part from shimano, i'm not sure if it's organic or metallic compound, i think probably resin pads... i'll try sanding it down or cleaning the rotors with what you suggested. thanks. – Juvil Sep 11 '13 at 1:28

Some frames are more prone to this than others. It seems to happen the worst with certain hardtail frames. It's possible that you swapped from organic to metallic pads which may have caused the issue to surface. Assuming this is the issue, sometimes the problem will go away as the pads bed in, other times not. If you can determine that you moved from organic to metallic pads and you are through the bed in period, you may want to swap back to organic pads.

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Try this,

  1. Galfer pads, standard pads a pretty grippy and quiet!
  2. Burn in.
  3. Clean with neat alcohol, available from most DIY shops, at least in Spain for about €2 a litre.
  4. Do not contaminate, keep chain and derailleur lubrication well clear.
  5. Tight mounting bolts.

Hope that helps. MM, Hondon de las Nieves, Spain

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