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  1. #1
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    New bike - Hydraulic brakes too tight?

    I just bought a new Trek that came with Hayes Dyno Hydraulic brakes. Went for the first ride today after taking off the wheels at the shop to fit in my car. About half way into a short ride the rear brake started squeaking. By picking up the rear wheel I could tell the brake was rubbing because it slows down the wheel really quick.

    My guess is I might have depressed the lever with the wheel off. Would this throw the piston off? How do I fix this? All of the brake lever adjusters are screwed all the way in so I cant adjust by hand from there. Dont tell me I need to bleed them in order to fix it. Never done that before...Actually first time with Hydraulic brakes on a bike.

  2. #2
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    If you could get the wheel in, then you should be fine.

    Is the QR tight? If so, then read on.

    It sounds like you need to realign the calipers on the rotor, going by your description. If that is the case, loosen the bolts holding the caliper to the frame, squeeze the lever (this should centre the caliper on the rotor) and slowly/gently retighten the bolts.

  3. #3
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    Well make sure your wheel is in tight and correct before aligning caliper or you'll have to align it again.

    Now Hayes tells you a lot of thing but I have always found the eyeball works best, just look at the caliper/rotor contact from the same plane as the rotor - you should be able to see a very small gap on each side of rotor. If the rotor is contacting either or both pad, should be easy to pick up.

  4. #4
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    Thanks for the info. The squeak is gone and the wheel spins freely, but now I have a slight rub on only one part of the rotor. Such as if the rotor is warped. I dont see anything wrong on that part of the rotor either.

    If I look straight down at the rotor spinning it looks perfectly straight. Like i said this is brand new. Any ideas?

  5. #5
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    It does not have to be marjorly warped. Listen for the spot that is at issue and gently use your fingers to try straightening it. I believe that Pink Bike had a tech tuesday on rotor straightening by hand at some stage, so that might be worth a look.

    Good luck.

  6. #6
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    A low amount of wrap in a new rotor (all rotors) is normal. You can try to clean the surfaces so you don't have dirt between hub and rotor.

  7. #7
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    If you didn't take note of how tight the QR was when you removed the wheels at the shop, it's very likely you just didn't tighten it the same which can cause the wheel (and rotor) to be in a slightly different position.

  8. #8
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    I have a similar problem when I changed the pads. Even when I push the pistons back they move out against the disc.

    Can I just open the bleed screw and let a bit of fluid out or would I be better doing a full bleed?

  9. #9
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    Quote Originally Posted by MREGAN View Post
    I have a similar problem when I changed the pads. Even when I push the pistons back they move out against the disc.

    Can I just open the bleed screw and let a bit of fluid out or would I be better doing a full bleed?
    How are you pushing the pistons back? It is recommended that you use a plastic tyre lever and apply pressure evenly. I put the lever through the caliper and apply pressure using both hands on either side.

    I doubt you need to do a bleed.

  10. #10
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    How are you pushing the pistons back? It is recommended that you use a plastic tyre lever and apply pressure evenly. I put the lever through the caliper and apply pressure using both hands on either side.

    I doubt you need to do a bleed.
    There is no issue with moving them back they move easy enough with the edge of a spanner. The problem is they dont stay back they slowly move back out. I can get the wheel in but it is tight. If I rode it like this I will go through the pads in no time. Doing some research it sounds like there could be too much fluid in the lines?

  11. #11
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    Quote Originally Posted by MREGAN View Post
    There is no issue with moving them back they move easy enough with the edge of a spanner. The problem is they dont stay back they slowly move back out. I can get the wheel in but it is tight. If I rode it like this I will go through the pads in no time. Doing some research it sounds like there could be too much fluid in the lines?
    Maybe a problem with the seals? In any case, it obviously wouldn't hurt to bleed them so that's worth a shot.

    Maybe you should start another thread to get some more eyes looking at your problem...

  12. #12
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    You just bought new from where? LBS? Have them fix it.
    “Wise men speak because they have something to say; Fools because they have to say something.” - Plato

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    When I replaced with Kool Stop on Elixirs, new grab resulted in a lot of drag.
    Question:
    What's the most logical DIY way to reduce/eliminate this w/o bleeding?
    I don't want to open the lines.

    Thanks.

  14. #14
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    Quote Originally Posted by awesomepaw View Post
    When I replaced with Kool Stop on Elixirs, new grab resulted in a lot of drag.
    Question:
    What's the most logical DIY way to reduce/eliminate this w/o bleeding?
    Can you clarify what you mean by drag? Do you mean that the brakes weren't stopping very well? If so, assuming you don't know this already, new pads need to be broken in. Do a bunch of light stops with the new pads, until they feel decent. If that's not it, then maybe your rotor is not clean and should be cleaned with something like isopropyl alcohol.

  15. #15
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    Hello folks,

    The issue of bleeding is only a requirement if you have a mushy lever, or have opened the system.

    Rotor clearance is .006-.008" either side. Rotors are out of true from the factory and must be trued before use. This requires the use of a dial indicator on a wheel truing stand. Dragging brakes cause the fluid to expand, thus dragging worsens as you ride.

    I agree with Aeros...back to bike shop for resolution

  16. #16
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    Rotors are true and clean. Drag - like friction that doesn't let the wheel spin freely, slowing only due to loss of momentum. The pads are not causing any audible sound, just v-lightly touching the rotor. Wasn't sure how much breaking in it would take before this weekend. Been out for one 2.5 hr ride and going for another now, but basically it looks like there's simply too much material on the new pads, i.e. the break in time needed. I thought given I depressed the calipers enough to allow the rotor in that'd be good. Should you have any other suggestions, thanks in advance.

  17. #17
    gran jefe
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    what about the spring that pushes the pads apart? is it there? is it damaged in any way?

  18. #18
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    They are probably seal retracted pistons with anti-rattle springs.

  19. #19
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    Quote Originally Posted by awesomepaw View Post
    The pads are not causing any audible sound, just v-lightly touching the rotor ... it looks like there's simply too much material on the new pads. I thought given I depressed the calipers enough to allow the rotor in that'd be good. Should you have any other suggestions, thanks in advance.
    Did you push the pistons all of the way back in before putting in the new pads? Maybe they're in position for the old pads? Maybe the caliper isn't aligned with the rotor?

    Personally, I'd double-check the pistons are in all of the way in. Then, I'd ensure the caliper was aligned properly.

  20. #20
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    Clean pistons and use a q tip soaked with slick 50 1 lube to lubracte the pistons. Retract the pistons all the way then CAREFULLY operate the lever to drive the pistons out part way. Swab with lube again. Retract the pistons all the way again. The trouble is usually the seals dry out and begin to stick. This problem is prevalent with 4 piston brakes. The " H" spring should have 6-8 mm space between the ends for proper tension. I have been using DOT 5.1 silicone in my Avid Codes to prevent them from sticking.

    If you run the pistons out all the way lubing with brake fluid will resolve the problem. They are assembled dry at the factory which. Does not help.


    BTW All Avid brakes use an h spring to my knowledge.

  21. #21
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    Good thought BR! Will give that a to try stretch their life a bit more. Thanks.
    Last edited by awesomepaw; 12-12-2011 at 10:56 AM.

  22. #22
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    Np....let us know the results!

    I have experienced this trouble with 4piston automobile brakes as well.

  23. #23
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    Quote Originally Posted by pitbull30 View Post
    I just bought a new Trek that came with Hayes Dyno Hydraulic brakes. Went for the first ride today after taking off the wheels at the shop to fit in my car. About half way into a short ride the rear brake started squeaking. By picking up the rear wheel I could tell the brake was rubbing because it slows down the wheel really quick.

    My guess is I might have depressed the lever with the wheel off. Would this throw the piston off? How do I fix this? All of the brake lever adjusters are screwed all the way in so I cant adjust by hand from there. Dont tell me I need to bleed them in order to fix it. Never done that before...Actually first time with Hydraulic brakes on a bike.


    How did you end up fixing everything?

    You have a 2012 Cobia? I think I have the same issue you were, however the prescribed method of fixing with the lever down and then re-attaching the wheel doesnt seem to work for me.

  24. #24
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    Flat blade screwdriver between pads, gently push against pads to run pistons back. Be gentle so pads do not become damaged....easy fix!

  25. #25
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    Yeah, I somewhat haphazardly used pneumatic tool oil and rushed the cleaning with a degreaser like Simple Green, as well as the lubing. Not the desired result, of course. Probably attracted even more dust and dirt. However, the DH section of the ride broke it the pads to eventually rid the singing rotor. Gawd, that's annoying! I will do correctly once more tonight and get back.
    Would pneumatic tool oil be okay for lubing the piston/"caliper"?

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