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  1. #1
    The Missing
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    formula R1 stubborn piston issue

    I have a set of 2010 Formula R1 brakes and am having some issues with the front brake. The performance is just not there for getting the front to lock up. I have had these brakes for two seasons and with ease I have always been able to lock the front or rear with just one finger. I put in new pads (sintered), rotors, new lines and bleed the lines a few times now but still no dice (took brakes of my 26 and put on my 29er ) . Pads and rotors were properly seated. The feedback from the lever is there feels great (no air in line).

    I have a stubborn piston that is not moving much at all and tonight I will try to get it to loosen up, last week I hit it hard with alcohol and dot 4 fluid but still am not getting one of the pistons to pump with the ease of the other side. Does this sound like I need to replace the piston and the seal for this front caliper perhaps?

    Tonight I am going to saturate the piston with silicone lubricant and see if that gets the piston to slide with more ease as the dot fluid alone on the piston is not loosening it up enough.

    Would a semi seized piston cause a deterioration in performance I have read many people associating brake noise and rub with seized pistons but not necessarily a performance issue? The front brake is howling when I try to get it to lock up. I got it to lock up a few times last night but only with two fingers and a whole lot of force on the lever. This is not the performance I am used to getting with formula.

  2. #2
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    Quote Originally Posted by pernfilman View Post
    I have a set of 2010 Formula R1 brakes and am having some issues with the front brake. The performance is just not there for getting the front to lock up. I have had these brakes for two seasons and with ease I have always been able to lock the front or rear with just one finger. I put in new pads (sintered), rotors, new lines and bleed the lines a few times now but still no dice (took brakes of my 26 and put on my 29er ) . Pads and rotors were properly seated. The feedback from the lever is there feels great (no air in line).

    I have a stubborn piston that is not moving much at all and tonight I will try to get it to loosen up, last week I hit it hard with alcohol and dot 4 fluid but still am not getting one of the pistons to pump with the ease of the other side. Does this sound like I need to replace the piston and the seal for this front caliper perhaps?

    Tonight I am going to saturate the piston with silicone lubricant and see if that gets the piston to slide with more ease as the dot fluid alone on the piston is not loosening it up enough.

    Would a semi seized piston cause a deterioration in performance I have read many people associating brake noise and rub with seized pistons but not necessarily a performance issue? The front brake is howling when I try to get it to lock up. I got it to lock up a few times last night but only with two fingers and a whole lot of force on the lever. This is not the performance I am used to getting with formula.
    I've fixed sticking piston by cleaning with alcohol. . hold the working piston retracted inside the caliper as you pump the leaver to get the sticking one extended (not too far). Clean it good and put some dot fluid in there and work that sucker in and out till it frees up.

  3. #3
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    I have a stubborn piston also. And it's also on the front. When I hold the working piston the stubborn works fine. Cleaned it with alcohol and it's still stubborn.
    Could this be due to low brake fluid? Some how my dot 4 fluid grew legs and walked away from me. So I'm going to get some tomorrow and try draining and refilling my lines.
    uʍop əpıs ɹəqqnɹ əɥʇ dəəʞ ɹəqɯəɯəɹ pəɥsɐɹɔ əʌɐɥ ʇɥƃıɯ noʎ sıɥʇ pɐəɹ uɐɔ noʎ ɟı

  4. #4
    The Missing
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    hit the piston with some silicone fluid lubricant spray that should free it up, freed mine up tonight, but I am still lacking the braking performance up front.

  5. #5
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    I hit it with some silicone spray last night and now it's working better but still not as freely as the other piston. I'm going to try working it a bit more when time allows.
    I lost some braking power but not much. But I did have a bad squeal/dragging noise from where the rotor was rubbing the caliper.
    uʍop əpıs ɹəqqnɹ əɥʇ dəəʞ ɹəqɯəɯəɹ pəɥsɐɹɔ əʌɐɥ ʇɥƃıɯ noʎ sıɥʇ pɐəɹ uɐɔ noʎ ɟı

  6. #6
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    Is this a common problem with these brakes. Been looking at some on Ebay.

  7. #7
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    Not specifically. All discs have sticking piston symptoms from time to time. I've actually found my R1's to be much better for that than other brands, YMMV
    Rimmer - "There's an old human saying - if you talk garbage, expect pain"

  8. #8
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    Quote Originally Posted by AlexRandall View Post
    Not specifically. All discs have sticking piston symptoms from time to time. I've actually found my R1's to be much better for that than other brands, YMMV
    That's nice to know. But all I've ever run were Shimano XT's and until now I don't ever recall having the problem I'm having now. I've only had these brakes for a little over a year. I'm ready to sell mine and go back to Shimano. I just got done trying to loosen up mine some more. With no luck It's moving but nothing like the other side. Just out of curiosity I thought I would check the rear brake and just as I figured. One side is moving much more than the other. But it's not enough of a difference to cause trouble. On both the piston on the side that the hose attaches to is the problem. Anyone think it would help if I replace the o-rings? If so how in the hell do you do that?

    So Bob, I can probably make you a geed deal if you want mine.
    uʍop əpıs ɹəqqnɹ əɥʇ dəəʞ ɹəqɯəɯəɹ pəɥsɐɹɔ əʌɐɥ ʇɥƃıɯ noʎ sıɥʇ pɐəɹ uɐɔ noʎ ɟı

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