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  1. #1
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    Brake help - Avid Elixir R - Pistons not retracting all the way

    So I am having some strange behavior with my Avid Elixir R's from a 2010 Stumpjumper, and hoping someone out there might be able to help. My brake lever started to feel extremely firm and my pads were not pulling back much off the rotor when I would release the handle. I removed the wheel, pushed the pistons back in, but after remounting the wheel they would come back into contact with the rotor and not retract enough when the lever was released. When the wheel was removed, I could see that the pistons would come out when I pull the lever, and then go back in to the caliper as expected when I released the handle, so it seems like it is not a stuck piston, but I am not sure. I figured I would do a bleed since it had been a while on that wheel. After the bleed, the behavior was the same, but one strange thing was that during the bleed I could hear air coming and going from the lever area during the pressure/sunction cycles of the bleed. I know this can't be good, but would a leaky lever cause the behavior I am seeing with the pistons not retracting normally? I am going to order a lever rebuild kit, but wanted to ride in the morning so wondering if there is something simple that I am just missing? Thanks!

  2. #2
    thecentralscrutinizer
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    Try the bleed first. Get some brake cleaner from the local parts store and squirt that on the pistons to remove dirt and such. Seems like this happens to me every year.
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  3. #3
    bro not pro
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    I've been told that this is the problem with all Avid hydraulic brakes ... they use DOT 5.1 fluid for it's extreme boiling point - which is fine, except the seals they use aren't compatible with the fluid, and after a while the seals swell. The swollen seals causes the pistons to not retract easily, and also uses up volume which also tends to push out the pistons.
    G O N Z

  4. #4
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    Thanks guys. So maybe I need a piston seal kit. Is it worth taking everything apart first and cleaning the pistons and seals, or should I just put in a new kit?

  5. #5
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    Quote Originally Posted by Gonz View Post
    I've been told that this is the problem with all Avid hydraulic brakes ... they use DOT 5.1 fluid for it's extreme boiling point - which is fine, except the seals they use aren't compatible with the fluid, and after a while the seals swell. The swollen seals causes the pistons to not retract easily, and also uses up volume which also tends to push out the pistons.
    This is for real??? Any references? Why would a company use seals that aren't compatible with the recommended fluid?

  6. #6
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    Hi,
    What did you do to fix the problem?
    I've just bought a 2010 Boardman with Elixir R brakes and have exactly the same problem.
    I've bled them, tried cleaning the pistons a bit when they're slightly exposed but they still don't retract very well.

    If you did go down the route of rebuilding did you do both the lever & the calipers?
    My levers also hiss a bit.

    I've only just learnt how to bleed brakes... the thought of rebuilding them is a bit daunting.

  7. #7
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    So I removed the pistons from the caliper and cleaned them off as well as cleaned off the piston seals as good as I could without taking the caliper apart. I then put everything back together, did another bleed, and still had the issue. I was to the point where I was just going to buy a whole new set of brakes but thought I would just try a whole new piston rebuild kit for $10 from Amazon. It included new pistons, new piston seals, and new caliper seals. I took the caliper apart, removed the pistons, and replaced all the seals, and it fixed it. Not sure if there was a slight imperfection in the seals or pistons, or what the issue was, but the new kit fixed it. I probably need to rebuild the lever too, but for now everything is working well so I don't want to mess with it.

  8. #8
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    Thanks a lot for taking the time to reply - that's a big help.
    I was going to have a go at bleeding the back tonight (did front last night but hasn't made much of a difference) - but I reckon I'll get the caliper kit first and do what your did so I don't end up going through the hassle of bleeding second time.

    Thanks again!

  9. #9
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    Quote Originally Posted by azxd04 View Post
    So I removed the pistons from the caliper and cleaned them off as well as cleaned off the piston seals as good as I could without taking the caliper apart. I then put everything back together, did another bleed, and still had the issue. I was to the point where I was just going to buy a whole new set of brakes but thought I would just try a whole new piston rebuild kit for $10 from Amazon. It included new pistons, new piston seals, and new caliper seals. I took the caliper apart, removed the pistons, and replaced all the seals, and it fixed it. Not sure if there was a slight imperfection in the seals or pistons, or what the issue was, but the new kit fixed it. I probably need to rebuild the lever too, but for now everything is working well so I don't want to mess with it.
    Been there, done that. That will get you anywhere from 3 months to a year of trouble free braking, depending on how often you ride. The problem will come back.

  10. #10
    bro not pro
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    Quote Originally Posted by azxd04 View Post
    I took the caliper apart, removed the pistons, and replaced all the seals, and it fixed it. Not sure if there was a slight imperfection in the seals or pistons, or what the issue was, but the new kit fixed it. I probably need to rebuild the lever too, but for now everything is working well so I don't want to mess with it.
    admire your work.

    I had a bike shop rebuild mine, and paid $100. Lasted until the pads wore out. could not press the pistons back in far enough to make space for the new pads. opened up the bleed port on the caliper and let a little fluid out while pressing the pistons in ... proof that Avid seals swell.
    G O N Z

  11. #11
    Now, THAT'S gonna hurt!
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    I just got through rebuilding both of my Elixer CR calipers and one of my levers that was leaking during the bleed process. I replaced 2 of the 4 pistons because they had a tiny little ridge built up where the seals had settled. It was preventing those specific pistons from extending outward as far as they needed to during braking and it caused the functioning piston to slightly bend the rotor towards the non-extending piston/pad and the brakes would squeal. I have 2 neighbors that were having the same issue so I enlightened them to pull the pistons and clean and their problems have stopped.

    Has anyone abandoned the 5.1 fluid and gone with straight DOT 4 in these newer systems? The manual says that they recommend either 5.1 or 4 but they are charged with 5.1 from the factory. I know it's not acceptable to mix the 2 so maybe I'll flush my system and go back to a DOT 4 and see what happens with longevity of the seals.

  12. #12
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    Quote Originally Posted by Oh My Sack! View Post
    I just got through rebuilding both of my Elixer CR calipers and one of my levers that was leaking during the bleed process. I replaced 2 of the 4 pistons because they had a tiny little ridge built up where the seals had settled. It was preventing those specific pistons from extending outward as far as they needed to during braking and it caused the functioning piston to slightly bend the rotor towards the non-extending piston/pad and the brakes would squeal. I have 2 neighbors that were having the same issue so I enlightened them to pull the pistons and clean and their problems have stopped.

    Has anyone abandoned the 5.1 fluid and gone with straight DOT 4 in these newer systems? The manual says that they recommend either 5.1 or 4 but they are charged with 5.1 from the factory. I know it's not acceptable to mix the 2 so maybe I'll flush my system and go back to a DOT 4 and see what happens with longevity of the seals.
    There's a lot of confusion between DOT 5 and 5.1 fluids. DOT managed to confuse things by making the glycol base compatible fluid with a .1 suffix and the non compatible silicone based fluid seem to be a continuation of the 3, 4 series. Even I get confused and have to check to be sure and I already know that it's problematic.

    So there should be no problem going to or somewhat mixing - DOT 4 and 5.1. DOT 5 [silicone] is slightly compressible which would give a spongier feel to the brake and the boiling point is no different from 5.1 so nobody uses it that I've heard of. There's some rumours of 5.1 having some polyborate additive that can swell seals but I'm no chemist so I'll leave that as something to spend a winter evening googling.

    If the seals actually do swell with 5.1 over time, it shouldn't be enough to affect the total fluid volume appreciably. Since we're looking at a boiling point difference of something like 430 vs 460 degrees - or something like that - I don't see the point of using DOT 5 for typical usage by people who don't get their rotors glowing.

    I'm still running the original factory bleed on some made in late '10 R-SLs which are working perfectly. I'm planning on doing nothing other than pad changes and cleaning the pistons with alcohol before pushing them back in. How long can you go without even bleeding or anything? I don't care if the system is hooped in the end; I'm just curious to see how far I can go non maintaining them.

    Supposedly the fluid should absorb water over time, but I find it hard to believe that water can enter a system that fluid can't leave. Even cars have had a bladder seal in the reservoir that keeps the air off the fluid since maybe thirty years ago. Quite how the water gets in is a mystery to me.

  13. #13
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    My seals swelled up and now they block even the wider diameter of the taperbore. It means it's impossible to bleed them!

  14. #14
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    Quote Originally Posted by Gonz View Post
    admire your work.

    I had a bike shop rebuild mine, and paid $100. Lasted until the pads wore out. could not press the pistons back in far enough to make space for the new pads. opened up the bleed port on the caliper and let a little fluid out while pressing the pistons in ... proof that Avid seals swell.
    I'm sorry but I find your idea about the seals swelling a bit ludicrous. Just more hate for the Avid brakes. If you were correct, Avid brakes would all fail which is far from reality.

    Getting the pistons to fully retract sometimes requires that the bleed screw be loosened a little to allow any excess brake fluid to escape when retracting the piston. Once the pistons are fully retracted it is important to make sure the bleed block is fully inserted to keep the pistons from extending while doing a bleed, which you would have to do now that the system has been opened. If for whatever reason the pistons are not secured during the bleed, they will extend and you will have difficulty getting the pads pack in once you've re-installed the wheel.
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  15. #15
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    Meet a swelled seal.

    The only things that have touched this seal are dot 4, dot 5.1 and air. The seal has swelled and then got chewed up as it tried to enter the smaller diameter of the taperbore. It's off a 2010 Elixir CR.

    Brake help - Avid Elixir R - Pistons not retracting all the way-140909-0539.jpgBrake help - Avid Elixir R - Pistons not retracting all the way-140909-0540-002-.jpg

    Compare it to the ideal , new seal:

    Avid Elixir Cr R 5 Mtb Lever Internals Service Kit - Avid Mtb Brake Spares - 2013 Avid Braking - 2013 Mountain Bike Gear - by Avid - 2012 Avid Elixir Cr R 5 Mtb Lever Internals Service Kit Avid Lever Internals Service Kit Elixir Cr R 5 1 Pc - Buy fro

    Any yet, I LOVE my Elixirs!

  16. #16
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    I know what a swelled seal looks like and that is not what I had taken issue with from Gonz. Gonz was attributing seals swelling due to incompatibility with DOT 5.1, and that this is an apparent known design flaw with Avid brakes.

    Good luck repairing your brakes and I also like my Elixirs.

    P.S. hard to tell what is going on with your seal. Picture is of poor quality. All I can see is that the seal has been damaged somehow and looks to have broken apart.
    Last edited by Jetta2010; 09-09-2014 at 08:38 AM. Reason: new info
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  17. #17
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    Yeah the weird thing is that they only failed once I took them apart (long story, but a bike-check for an event made me replace the hose). It's almost like they're a few years old but the seals are okay as long as they're immersed in fluid and then...bang, as soon as they hit the air they swell.

    This phenomenon may well be a result of the fact that the seal is being squeezed and expanded all the time in the taperbore.

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