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  1. #1
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    Help wanted with XT M755 front brake

    Hi all!
    My front brakes have lost their bite!
    After I filled some fluid and adjusted the lever distance, I don't get nearly as much brake power as before. You probably know that these have 4-piston calipers and one finger used to be quite enough to bring me to a quick stop. The rear brakes still locks the wheel easy with two fingers, but I have to use all my power to lock the front, and my old Pro-Max V-brakes is now MUCH more effective. Of course I have bled the calipers, but this didn't help.
    As far as I can see, the disc seems centered in the caliper gap.

    Are there other things I could try? I am really thankful for any help!

  2. #2
    Nightriding rules SuperModerator
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    Do the levers feel mushy? or they feel good, but lack power?

    Did you make sure not to get any mineral oil on the pads/rotors while adding?

  3. #3
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    I would say that the feel of the front brake lever is the same as on the rear, the difference being that I have to pull 3 times harder on the front to get the same braking power as the rear...
    No oil on pads or rotors, I have also cleaned them thoroughly with brake cleaner.
    This is all very confusing.

  4. #4
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    Quote Originally Posted by the_engineeer
    I would say that the feel of the front brake lever is the same as on the rear, the difference being that I have to pull 3 times harder on the front to get the same braking power as the rear...
    No oil on pads or rotors, I have also cleaned them thoroughly with brake cleaner.
    This is all very confusing.

    If you didn't remove the pads when you bled the brakes then guess what>>>>

  5. #5
    Stucco Bucket
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    Im having the same issue except its the back that has lost power.
    I also hear a clunking sound before engagement, that the front doesnt have.
    I did the bleed out last night to try and remedy, but didnt help

  6. #6
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    Quote Originally Posted by the_engineeer
    ...................
    No oil on pads or rotors, I have also cleaned them thoroughly with brake cleaner.
    This is all very confusing.
    There's your problem. You used brake cleaner on them. Use alcohol next time. The pads are no good now. You can roast them to burn off the contaminants.

  7. #7
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    I tried a new set of pads also, but the problem remains...
    Oh, and I just noticed that the bottle of cleaner I used, is 100% pure ethanol.

  8. #8
    DGB
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    Flame the pads!
    If in doubt, run the pads over a gas burner until they get very hot. If you see some smoke from the pads, that's the contaminant burning off. Cool the pads in water, clean the rotors with IPA, refit pads and away you go.

    I'm sure this advice is in the FAQs (if not it should be or else put into a sticky).

    If this hasn't solved the problem, then it's more likely down to a bleed issue. I've done this on occasion with my XT M775's pads and it has improved bite.

  9. #9
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    If you stuck new pads on and expect them to suddenly be excellent first stop then think again. You have to bed them in like the brake was new again. You could also have issues with residue on the rotors too.
    Rimmer - "There's an old human saying - if you talk garbage, expect pain"

  10. #10
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    Yeah, I know that the pads need running in, but the problem was the same with the old pads (and they weren't worn down, I had at least 50% remaining). I will try to clean the rotors tonight though, it couldn't make things worse...

  11. #11
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    Roast both the pads and rotor. Then sand then and then rinse them with plain water. Then find a long safe hill and bed them in. Then come back and tell us what happens.

    Of course if you get new pads and rotors, just go bed them in.

  12. #12
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    OK, I used a blowtorch on the rotor and the pads. Definitely an improvement, still not quite as good as the rear brake but I'm going to do another roast and then sand them also. I wonder if I can hide the rotor in the dishwasher when my fiancee isn't looking? ;-)

  13. #13
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    Yay!
    My brakes are back to their good old "one-fingered-Endo" capability!
    I torched the rotor again, then let it soak for an hour in 24% ammonium hydroxide and as an afterthought chucked it in the dishwasher. Squeaky clean. Then I sanded my new set of pads and bled the calipers thoroughly.
    Thanks for all help!

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