Left out under the sun?- Mtbr.com
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  1. #1
    Noli Me Tangere
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    Left out under the sun?

    I hope some of the MTBR brake guys can help me with this one...

    I have a Fisher Hi Fi Plus with Juicy 3's with a shade under 1000 miles on it. This problem has just surfaced: whenever I leave the bike under the sun i.e.left on the bike rack or resting on the trail, the rear brake lever goes 'limp' and doesn't snap/spring back and the rear piston gets stuck in the out position enough to lock the rear wheel.

    I've taken it to my LBS and at first I was told that the pads needed to be replaced that it was so worn out that the pistons would stick out far enough that it wouldn't retract. So the pads were changed. After a break-in ride for the brake pads, the bike (on the rack) being under the sun the rear lever goes limp again and the rear brake is stuck again. Wheel wouldn't even do a full revolution. Took it back to the same LBS and was told maybe theres air in the line and just needs to be bled. That was also done and picked the bike up a day later.

    When I picked up the bike it was obviously left out under the sun (bars, frame and saddle were hot to the touch) and sure enough the lever was dead/limp and the rear brake was stuck again. This time I was told that the master cylinder must have gone bad and needs to be rebuilt and it might be preventing fluid to flow back. 2 hours later I was told that Juicy 3's have been discontinued and there are no parts for it. So now I have the Fisher sitting on a stand in the garage (its never hung) in the mean time.

    I tried to describe the problem the best I could. Can someone help? Here's a few more info that might help:

    *212 LBS rider + gear

    *Heavy rear brake user

    *Ridden in typical Southern California XC-type trails

    *Roundagon rotors

    Did the LBS wrench miss something? Lines were not properly bled? Not enough brake fluid? Upgrading to a better brakeset isnt in the budget right now.

    Thanks in advance
    Annie are you ok? Are you ok, Annie?

  2. #2
    local jackass
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    change your fluid. its just like a race car under heavy braking if the fluid gets to hot the pedal goes limp so try to keep the fluid from getting so hot if you can and maybe look into Super blue brake fluid as it is made for higher heat conditions
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  3. #3
    Noli Me Tangere
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    I would have had that done but the front brake doesnt do that. The front stays the same.

    This doesnt happen during heavy braking either
    Annie are you ok? Are you ok, Annie?

  4. #4
    Noli Me Tangere
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    Oops double tap
    Last edited by Dial Tone; 06-01-2010 at 10:22 PM. Reason: oops
    Annie are you ok? Are you ok, Annie?

  5. #5
    Ride Responsibly
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    Crimped or blocked hose?

  6. #6
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    Sounds like some air in your brake line, causes what biggoofy1 suggested to happen when it gets hot.

  7. #7
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    My guess is that that master cylinder cover vent hole is blocked. The pocket of air is expanding against the rubber diaphragm, pushing fluid down the hose to the caliper. This would cause both problems you mention.
    The race car analogy above is referred to as 'brake fade.' It happens when a brake pad exceeds it's operating range and begins gassing between the pad and rotor, reducing contact area. As you already know, this isn't happening to you.
    I'd recommend removing the cover to check the vent hole instead of stabbing something through from the outside, risking damaging the rubber membrane.

    Keep us posted.

    -Lule

  8. #8
    Noli Me Tangere
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    Quote Originally Posted by Lule
    My guess is that that master cylinder cover vent hole is blocked. The pocket of air is expanding against the rubber diaphragm, pushing fluid down the hose to the caliper. This would cause both problems you mention.
    The race car analogy above is referred to as 'brake fade.' It happens when a brake pad exceeds it's operating range and begins gassing between the pad and rotor, reducing contact area. As you already know, this isn't happening to you.
    I'd recommend removing the cover to check the vent hole instead of stabbing something through from the outside, risking damaging the rubber membrane.

    Keep us posted.

    -Lule
    Thanks Lule, I'll check that.
    Annie are you ok? Are you ok, Annie?

  9. #9
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    So what was it?

  10. #10
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    I have the exact same issue on my 3's except it is the left lever.

  11. #11
    Noli Me Tangere
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    Quote Originally Posted by Lule
    So what was it?
    I haven't gotten around to it... I guess thats the benefit of having a stable.

    I checked the Avid PDF and couldnt see where the vent hole would be. Looked around the levers as well. If you can, post a pic please?

    Yesterday I rode my Bandersnatch with BB7's and didn't have any issues with stopping power and modulation was great. But I'm not going to downgrade to mechs just yet. Well adjusted the BB7's + Speed Dial's might be, I can feel the cable stretch and the extra effort.

    Quote Originally Posted by dblvanos
    I have the exact same issue on my 3's except it is the left lever.
    Lever goes 'dead' and wont snap back? Piston getting stuck and prevents the wheel from spinning? Have you taken it to a shop and what was the outcome?
    Annie are you ok? Are you ok, Annie?

  12. #12
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    Quote Originally Posted by Dial Tone
    But I'm not going to downgrade to mechs just yet.
    Ouch! I have mechanicals. Jagwire Ripcord cable and housing make them much improved.

    The vent hole is located on the centerline between the cover screws, below the text. It is smaller than the diameter of paperclip wire, thus the likelihood of blockage. This might
    be it.

    The lever assembly will have to be removed from the bar to access the cover. Some rather small Torx screws hold on the cover.

    Let us know.

    -Lule

  13. #13
    Noli Me Tangere
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    Thanks! I'll check it out when I get home. Good thing I got lock on Oury grips, that will cut down on the grip removal hassle. If the vent hole is smaller than a paper clip wire I suppose I can use sewing needle. Maybe some dirt have gotten in it. I hope its really something simple.

    As for the mechanical brakes on my Bandersnatch, I have Jagwire cables and housings (even the shifter cables) as well and they do seem smooth. But I still feel a bit of the cable stretch when clamping down.
    Annie are you ok? Are you ok, Annie?

  14. #14
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    Best of luck with the repair. Let's hope that's the problem. I feel that the 'stretch' you're feeling is probably the period where the rotor is being flexed/pushed over to the stationary pad.

    -Lule

  15. #15
    Noli Me Tangere
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    Quote Originally Posted by Lule
    I feel that the 'stretch' you're feeling is probably the period where the rotor is being flexed/pushed over to the stationary pad.
    You know what, I have not thought about it that way.

    I wish my garage had a TV with satellite; Lakers playing tonight and I dont think Mrs. DT would be happy if I brought the Fisher in the living room and fiddled with hydraulic brakes in front of the TV...

    I'll update this thread soon and take pics when I start messing with it.
    Annie are you ok? Are you ok, Annie?

  16. #16
    Noli Me Tangere
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    Ok quick update:

    Took a better look at the lever and found the vent hole as you described. It doesn't appear to be obstructed. I poked the hole with a sewing needle but not hard enough to puncture the rubber bladder/cylinder, and nothing. Definitely not obstructed. Will remove the cover tomorrow and see what it looks like inside.

    It wasn't warm today so I wasn't able to duplicate the stuck piston condition. Tomorrow I'll use a hair dryer to heat up the lever and see what happens.

    Question though, if I remove the lever cover will any brake fluid squirt out?
    Annie are you ok? Are you ok, Annie?

  17. #17
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    Update:

    Took off the reservoir cover. Some brake fluid dripped out but only very little. From that I can see, the rubber bladder is fine and in position.

    So I heated the lever with a hair dryer to duplicate heat from being undef the sun. Sure enough the lever goes dead and does not snap back. That proves the problem is at the levers not at the rotors being stuck. It does seem like when heat, the brake fluid does not flow back.

    Anyone else have an idea whats wrong?
    Annie are you ok? Are you ok, Annie?

  18. #18
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    Were you holding the reservoir level? ie so no fluid can fall out.
    If not then all the fluid in your reservoir would've spilled out, once again most likely air in your system. You need to bleed your brakes.

    if there is air in the system it allows the fluid to boil off quicker than if not.

  19. #19
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  20. #20
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    You're on the right track with the hairdryer. Did you heat the lever assembly with the reservoir cover on or off? The problem is most definitely expansion of a gas(air). You now know it's at the lever assembly, not at the caliper or brake line. The air is somewhere between the primary plunger seal and the rubber diaphragm. The expanding air is pushing on the plunger. I feel a careful bleeding of the lever assembly will fix this problem. The rubber diaphragm just didn't have enough room to allow for the expansion of that much air. It's job is really to flex inward when applying the brakes to compensate for the fluid being pushed down the line.

    The Park tool 'how-to' seems comprehensive and should do the trick.

    It sounds as if it's time to consider another shop.

  21. #21
    Noli Me Tangere
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    I heated the lever with the cover on and maybe the first 2-3 inches of the brake line. In a few minutes of being heated it went dead.

    I'll take it to another shop and have it re-bled this weekend. Thanks again!
    Annie are you ok? Are you ok, Annie?

  22. #22
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    Sure! It can be a bit treacherous at times with no rear brake.

    -Lule

  23. #23
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    Quote Originally Posted by Dial Tone

    Yesterday I rode my Bandersnatch with BB7's and didn't have any issues with stopping power and modulation was great. But I'm not going to downgrade to mechs just yet.
    not exactly a downgrade considering the BB7s can stop you and your current Juicy 3's cant..

    There must be quite a bit of air in the system for the heat from the sun alone to cause the brakes to be completely useless... Typically, the heat from the sun isnt enough to heat the components to the temperature it would see during an extended downhill...

    But the question remains... if the system keeps getting bled, and then it works, only to have the heat from simply being in the sun cause the system to go useless.. you have to wonder how air is being introduced into the closed system to begin with..

  24. #24
    Noli Me Tangere
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    Good point. Like it sucked air in. I'll find out after I take it to another shop. The previous wrench said it could be a faulty master cylinder.
    Annie are you ok? Are you ok, Annie?

  25. #25
    C__Corax
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    it is the master cylinder i had the same issue. avid replaced with juicy 5's, last year.

  26. #26
    Noli Me Tangere
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    No rebuild kits available at the time when yours had the same problem?
    Annie are you ok? Are you ok, Annie?

  27. #27
    C__Corax
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    my LBS did a warranty replacement. Sram will do this also call them up and ask if you LBS is giving you problems.

  28. #28
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    DOCRIGID, do you know exactly what the failure was with the master cylinder?

  29. #29
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    My Fisher Hi Fi Plus is an 07 so it may be out of warranty already.

    Did some Googling on company time (take that The Man!) and found another thread here making mention of no master cyclinder build/rebuild kits available for the Juicy 3's. I hope that is not that case cause that would be totally bogus. I dont see how current brakes (I know they have moved to Elixirs now) could so easily be obsolete and be 'disposable'...

    Nevertheless I haven't contacted the LBS I got the bike from, maybe they could swing a warranty replacement or better yet, newer brakes.
    Annie are you ok? Are you ok, Annie?

  30. #30
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    Did some digging on Sram's site. Good news, bad news. The good news is that the current Juicy 3.5 uses the same master cylinder internals as your '07. Bad news is that there doesn't seem to be any currently available, but you already knew that.
    Another thought on the air issue. It doesn't make sense that the lever/plunger/mc can be sucking in air without fluid coming out when the pressure builds while in the sun. Leaks don't often happen in just one direction.

  31. #31
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    My old Juicy3's done the same thing all the time. Absolutely hated them, undependable as hell & always seemed to fail at the worst of times. I re bled them several times only to have the same problem arise time & time again. Needless to say I now run Hayes Strokers on my wifes bike & Stroker Ace's on mine, not a problem yet.

  32. #32
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    Yesterday while taking a rest after a climb my friend told my that the Juicy 3 rear brake on his Cannondale Scalpel was doing the same thing and didn't realize it was a problem until I posted a comment about in on Face Book. Lucky for him his Cannondale is still under warranty but the bike is only 5 months old!

    I checked along the lines and dont see any leaks including at the rotor. Maybe its something simple and small as a rip in an o-ring of the plunger.
    Annie are you ok? Are you ok, Annie?

  33. #33
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    Quote Originally Posted by Lule
    The race car analogy above is referred to as 'brake fade.' It happens when a brake pad exceeds it's operating range and begins gassing between the pad and rotor, reducing contact area.


    The pads reach a point where the friction they can generate drops off rapidly, not due to gasses, modern brakes don't produce gasses.
    Or...
    The fluid in the brake lines boils



    the wet boiling point for wet(slightly water contaminated) dot 3 is 284*F, so I seriously doubt it's getting hot enough sitting in the sun to make that happen.
    Quote Originally Posted by Qatarbhoy
    I have to ask for them to do a "Number two" on my head

  34. #34
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    Quote Originally Posted by karpiel666
    The pads reach a point where the friction they can generate drops off rapidly, not due to gasses, modern brakes don't produce gasses.
    I disagree.

    The slotting or cross-drilling of rotors on high-performance and racing vehicles is to release the gas that is produced from the heating of the pad from extreme use. This is not to be confused with 'glazing,' which is the surface of the pad changing it's chemical structure due to heat and pressure.

    Admittedly, I should not have used the word 'exceded', as gassing occurs within the operating range as well.

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