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Just checking I am not going insane over this...

I have Shimano MT400's on my commuter. The rear one works brilliantly. The front one though is awful. There is no "bite", very little power and a dreadful piercing squeal at slow speeds.

So far I have:

  • Made sure that the rotor isn't warped and the alignment is right
  • Noticed that one pad was wearing more than the other. Put new pads in and pushed out both pistons to apply some brake fluid as a lubricant. Pushed the pistons back in obviously!
  • Carefully bedded in new pads.

Another thing I have noticed is that when I reset the pistons it is taking quite a few lever pulls to get the pads back to the disc - normally it only takes a couple.

I am thinking that there is something wrong with one of the pistons - but want to make sure that there isn't anything obvious before I go replacing it (I don't like just binning things off, would rather fix).

Cheers

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    Your symptoms indicate air in the line. Try doing a mini/top bleed first and then you can progress to a full bleed. Commented Feb 20, 2023 at 14:30

1 Answer 1

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Your symptoms indicate air in the line. Try doing a mini/lever bleed first and then you can progress to a full bleed if you really need to.

You’ll need

  • A Shimano bleed cup.
  • Some mineral oil. It doesn’t need to be Shimano branded.
  • A 2.5mm hex wrench for the bleed port.
  • A 4mm hex for the brake lever.

You can do it at home in about 10-15 minutes. Take your time and be gentle with the small threads.

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