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Thread: ? about brakes

  1. #1
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    ? about brakes

    i have some Juicy 3s (7" on the front, 6" on the rear) that came on my 2010 Avalanche Expert, and i had a shop put new pads on about a month ago

    since then, ive done a lot of downhillish riding, lots of break usage...to the point that my rotors stunk (tho theyre not blue), and i even got some flats on the rear i had to deal with

    since fixing the flats, the rears are dragging like crazy..wtf!

    when i fixed the flats, i made sure i didnt hit the brake levers, so, wtf is going on

    did all the downhill breaking screw them up or what?

    i dont know much about disc brakes

    ill probably just take it back, and see what the mechanic says.

    thanks
    2010 GT Avalanche Expert

  2. #2
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    Possibly your wheel isn't aligned like it was before you changed the flat. You can re-align the caliper by loosening the mounting bolts a bit and moving the caliper until it doesn't rub.

    If that doesn't help because the pads are pushing against the rotor from both sides take the wheel off and push the pads apart a bit. A plastic bleed block is good for this because it won't damage the pads but a nice clean flat blade screwdriver can be used too if you're careful.

  3. #3
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    i just checked the wheel alignment, it looks good. the pads looked centered (as far as i can tell), but theyre SO close to the rotors

    unfortunately i dont have a bleed block, and im afraid ill screw them up with a screwdriver, so im just gonna take it back to the store

    i just wanna know why theyre doing what theyre doing? what causes them to get that close in the first place?

    thanks Phil
    2010 GT Avalanche Expert

  4. #4
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    Reset your pistons.
    Takes 10 minutes.
    1.remove wheel
    2. use a plastic tire lever to push the pads/pistons back to flush in the caliper. You can remove the pads or you can leave them in, just use something that won't damage the pads or pistons. If you leave the pads in, you can use a flat head screwdriver if a plastic tire lever wont fit, but wrap the tip in a few layers of duct tape so you don't chew up the pad surface. It can take some force to get the pistons flush.
    3. Install wheel and squeeze brake lever. Providing your caliper was properly set up, you should be good to go.
    4. If you get rubbing, repeat steps 1 and 2 and then do the following:
    5. Install wheel and loosen the caliper mounting bolts so the caliper floats.
    6 Eyeball and move the caliper so that the brake rotor is directly in the middle of the caliper and the pads are parallel to the rotor. Squeeze the brake lever, but keep the caliper in position. When the pads make contact with the rotor, tighten the caliper mounting bolts.
    7. Brakes should run drag free.

  5. #5
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    ok thanks

    but what can cause them to rub in the first place. i see no leaks or anything like that
    2010 GT Avalanche Expert

  6. #6
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    When your shop replaced the worn out pads with fresh ones they may not have reset the pistons properly or at all.

    I'm assuming your rotor is straight and true as well.

    No wobble in the rotor?

  7. #7
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    when the shop replaced the pads, they felt great

    the rotors look pretty dang straight.

    i got another question.. i read in MTB Action today that as the pads wear down, the pistons adjust to this so the pads can continue to touch the rotors and stop the wheel

    but how can that happen. seems the only way the pistons could move in closer

    ooops, never mind. just figured it out. the pistons move in as the pads wear, thats why the brake levers go soft. thats why you have to bleed them or add more brake fluid

    my bad

    fuk, im an idiot lol

    i still dont get why my pads have moved in so close and drag

    just thought of something, maybe when i was on the brakes a lot, the pistons heated up, swelled a hair, preventing them to return to their original spot, causing the pads to rub now

    i think im on a roll , lol
    2010 GT Avalanche Expert

  8. #8
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    Quote Originally Posted by nauc View Post
    i read in MTB Action today
    Stop doing that.

  9. #9
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    Quote Originally Posted by Norman Clydesdale View Post
    Stop doing that.
    no, it helped me understand how they work. it makes perfect sense now. expect im still not sure about pistons heating up and sticking and all that.

    maybe the brake fluid got super hot, expanded and moved the pistons more than they normally do?
    2010 GT Avalanche Expert

  10. #10
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    Quote Originally Posted by Norman Clydesdale View Post
    Stop doing that.
    is MTB Action no good? i like reading their reviews but i dont have much hand on exp
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  11. #11
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    Quote Originally Posted by nauc View Post
    i read in MTB Action today that as the pads wear down, the pistons adjust to this so the pads can continue to touch the rotors and stop the wheel

    but how can that happen. seems the only way the pistons could move in closer

    ooops, never mind. just figured it out. the pistons move in as the pads wear, thats why the brake levers go soft. thats why you have to bleed them or add more brake fluid

    my bad

    fuk, im an idiot lol

    i still dont get why my pads have moved in so close and drag

    just thought of something, maybe when i was on the brakes a lot, the pistons heated up, swelled a hair, preventing them to return to their original spot, causing the pads to rub now

    i think im on a roll , lol
    nah, no worries it is a pain

    But I would seriously recommend that you follow Norman's instructions AND take on the challenge of buying the avid bleed kit and doing it yourself. It is one of those things that is just a little tricky but very doable with the available resources online (youtube). And I view it as a threshold service; once you are comfortable you will feel like you can do almost anything on a bike including suspension oil and seal service, so you only need to spend $ when you really need a complicated damper rebuild.

    But to your questions: the pistons move in but this is not what makes pad go soft. pad goes soft because over time the fluid heats up over and over so much that air bubbles form inside the line...air in the line, that is what makes brakes feel squishy and need to be bled.

    You're close on the second hunch but the pistons swelling won't cause that, but dirt and grime could get between piston and caliper surface and make them not go back in as easy OR the pads may wear unevenly OR the seal between the piston and caliper can become damaged

    but seriously, it is so worth it to learn this service; it will all make sense

  12. #12
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    thanks

    i took the rear wheel off, and pushed the pads back with a metal ruler, being careful not to jack up the pads

    no rubbing now. ill keep an eye on it tho

    thanks everyone
    2010 GT Avalanche Expert

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