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  1. #1
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    Brake Pads Locked to Disc

    I need some advice on how to adjust my brakes.

    Got them bled about 6 months ago, worked perfectly til I went out of the country for 2 months. When I came back the rear brakes seemed to have locked up...? Not sure how or why, maybe the heat?

    Anyway, I got my rear wheel off to do some inspection. Seems like the calipers are pushing out too far so there's less room for the brake pads/disc. I pulled the brake pads out and I tried to push the calipers out with a flat-edged tool, but when i push one caliper outwards the other side moves towards the center.

    Not sure what else I can do, any advice?


  2. #2
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    What brand/model brakes are these? One thing comes to mind - you say you had the brakes bled. Is it possible incompatible fluid was accidentally used, as in mineral oil vs DOT 5, etc? Not exactly sure of the effect this would have or how immediate it would be - just a guess.

  3. #3
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    Quote Originally Posted by Betarad View Post
    What brand/model brakes are these? One thing comes to mind - you say you had the brakes bled. Is it possible incompatible fluid was accidentally used, as in mineral oil vs DOT 5, etc? Not exactly sure of the effect this would have or how immediate it would be - just a guess.
    They are Avid Elixir 7SL's. Well they were working like a champ for 6 months and somehow a month in the garage later this happened. Could it be the DOT fluid expanded? At one point I was thinking maybe it did and causing the brakes to pump slightly...help!

  4. #4
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    Brake Pads Locked to Disc

    Elixer 9s did this on a new bike I bought, I think LBS just had to bleed brakes to fix - apparently a finicky process with this brand/model. Air in line? Take it back to LBS to redo. Mine have been ok now for over a year since then.

  5. #5
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    One of my wife's bikes have Elixirs that did this after the bike sat in the garage for a few months. I figure the fluid was slowly getting water into it and expanded. Again, the same thing happened to a buddy's bike in Whistler after it had sat for a few months unused. A bleed fixed it as good as new, both times.

    A fix in a pinch/trail fix is to open the bleed port on the lever slightly while you push the pistons back to where they should be. You'll notice fluid coming out of the lever as you do this. Close it back up and finish the ride. Then do a real bleed as soon as possible. That's what we did in Whistler, although he rode it without a bleed for the rest of the week.

  6. #6
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    As said, rebleed.
    I have to wonder if the shop used fluid that was "old" already. What I mean used had been open for a while sitting around absorbing water vapor.
    Lead by my Lefty............... right down the trail, no brakes.

  7. #7
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    Aloha Deezy,

    I've seen this in the past as well. With a fresh bleed and new pads, there just isn't a whole lot of room in the caliper, lines and lever (master cylinder) for any expansion. DOT fluid likes to "wick" moisture out of the air. So with that additional volume, the only thing that can move are the pads toward the rotor (because the pistons move out).

    You tried doing the right thing by pressing the piston back in. However, because of the way the brakes work, if you push one piston in, all the pressure has to go somewhere which would be easiest toward the other piston. You're going to have to move the pistons in and bleed the pressure somewhere.

    Try this, get your hands on an old set of pads if possible. Put those in and have the wheel removed. Put the brake lever at the highest point AND the master cylinder fill port at the highest point. Remove the torx bolt at the fill port. While having someone with a paper towel, rag what ever at the lever fill port, you use a large screwdriver to pry both pistons into the caliper. Brake fluid should pour out the fill port. If it doesn't, that's OK. The main idea here is you are trying to get the pistons to push in and by removing the fill port screw, you give the pressure somewhere to go.

    After this, put the fill port screw back in, the pistons should be all the way retracted in the caliper. Put your pads back in (new ones hopefully) and then the wheel. Slowly pump the brake lever to seat the pads all the way. Your brakes should not be locked.

    Hope that helps.

  8. #8
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    Quote Originally Posted by gmats View Post
    Put the brake lever at the highest point AND the master cylinder fill port at the highest point.
    Can you explain what this means gmats?

  9. #9
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    They're Avids, that's par for the course unfortunately Immediate somewhat solution - take to the shop and get them bled, they will work again for a little while. Permanent solution - take off bike, buy XT or SLX install, no more worries.

    FYI for all those mentioning wrong fluid might have been used, that is a possibility, but know you are quoting the wrong fluids and that if you use DOT5 instead of DOT 5.1 (which is what Avids use) you will most likely damage the seals as they are not even remotely close to the same fluid makeup.
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  10. #10
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    Quote Originally Posted by deezy3z View Post
    Can you explain what this means gmats?
    With the bike in a stand or the bike on level ground (upright), loosen the bolt holding the brake lever on the handlebar. Turn the lever so that the fill port (where you put the brake fluid in) at the highest point. This is to ensure that all bubbles/air/etc end up going up to the highest point. Hope that helps.

  11. #11
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    Quote Originally Posted by gmats View Post
    With the bike in a stand or the bike on level ground (upright), loosen the bolt holding the brake lever on the handlebar. Turn the lever so that the fill port (where you put the brake fluid in) at the highest point. This is to ensure that all bubbles/air/etc end up going up to the highest point. Hope that helps.
    like this right? sorry i'm noob to this.


  12. #12
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    Hey, no worries. We are all newbies at something.

    Almost right. That one little screw needs to be your highest point so that fluid does not leak out and let air in. The idea is when you push the pistons back in, that you don't loose any more fluid than you need to and that you do not introduce air into your brake system.

    Brake Pads Locked to Disc-lever_pic.jpg

    So in effect, if you turn the lever down so that the screw is the highest point, you should be good to go.

  13. #13
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    Quote Originally Posted by gmats View Post
    Hey, no worries. We are all newbies at something.

    Almost right. That one little screw needs to be your highest point so that fluid does not leak out and let air in. The idea is when you push the pistons back in, that you don't loose any more fluid than you need to and that you do not introduce air into your brake system.

    Click image for larger version. 

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    So in effect, if you turn the lever down so that the screw is the highest point, you should be good to go.
    PERFECT! makes complete sense now! i did just as you said and a little DOT fluid came out when i pushed out the brake pads. the brakes feel excellent now, possibly even better than before. thanks for the tips gmats.

  14. #14
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    Awesome! Congratulations. Great news. Just passing on the knowledge and experience. I've certainly learned a lot from others out there and school of hard knocks. Enjoy!!

    Before I forget, get a rag and some alcohol and clean up any residue from the fluid. It will eat paint etc.

  15. #15
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    its not that the fluid expanded, its because the seals expanded. this is a problem with Avid hydros - their seals are not compatible with the DOT 5.1 fluid, and they swell. When they swell it produces the same effect as the fluid expanding - causes the pistons to move out. That's why letting a little fluid out will alleviate the problem.
    G O N Z

  16. #16
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    So the seals on brakes designed to be used with DOT 5.1 are not compatible, have you done tests with the seals and different fluids then? Have to ask as I'd expect this sort of thing would be high on the priority list I'd think when designing and building these brakes. I can't say for sure why it happens, but for sure over time, most especially if the brakes are left to sit idle for long periods the only solution is the one Gmats gave or a bleed, which then in effect does the same thing, I've always thought there was an issue with the seals or something that let moisture get into the system causing the problem, but could not figure out how then the DOT fluid would not leak out - makes some sense, but honestly wouldn't think this is something they'd overlook.

    Quote Originally Posted by Gonz View Post
    its not that the fluid expanded, its because the seals expanded. this is a problem with Avid hydros - their seals are not compatible with the DOT 5.1 fluid, and they swell. When they swell it produces the same effect as the fluid expanding - causes the pistons to move out. That's why letting a little fluid out will alleviate the problem.
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  17. #17
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    thx again ya'll! hopped on the trail today and the brakes felt great! the stopping power is just ridic! can't wait to bomb down a hill now!

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