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Bleeding Avids?

Discussion in 'Downhill & Freeride' started by John P., Feb 2, 2008.

  1. John P.

    John P. Turbo Monkey

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    Hey guys-

    I've got a recurring problem with my Avid brakes, and seeing as how I've been running Hayes on all my bikes since the dawn of time, I'm not sure what the hell I'm doing wrong.

    Basically what happens is that if you happen to pull the brake lever (particularly the rear brake) while the bike is either upside down or standing on its rear wheel, the brake goes to mush - you can pull the lever all the way to the bar.

    Now I realize that the most obvious solution is just not to pull the brake lever when the bike is in those weird positions, but me being the dip$hit that I am, I often forget and do it anyway because I'm rolling the bike around my shop or working on it someplace and have the bike upside down.

    I'm assuming this problem is due to a bad bleed and there is air somewhere in the system that gets freed up and goes into the line when the bike is in these awkward positions, but I've had this happen when the brakes are straight out of the box, right after a bleed by a very good shop mechanic, and right after an anally-retentive, painstakingly precise bleed by yours truly.

    So I have 3 questions:
    1. Am I correct in assuming that this problem results from air hiding somewhere in the system?
    2. Where in the hell is the air hiding?
    3. How in the hell do I bleed it to get the air outta there?? Or is there someway I can get the brakes back to normal without re-bleeding?

    Thanks in advance, amigos.

    --JP
     
    #1 -   Feb 2, 2008

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  2. sethimus

    sethimus scroll all you want!

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    #2 -   Feb 2, 2008
  3. John P.

    John P. Turbo Monkey

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    Thanks, man. But I've seen that video and followed it exactly. I assume the factory followed those guidelines as did the shop who bled the brakes, too. Unfortunately, the problem still exists.

    And for what it's worth, I've had this happen on two different bikes with two different types of Avids (the sevens on one bike and the fives on another).
     
    #3 -   Feb 2, 2008
  4. FreeRide-Junkie

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    I have had that happen on customers Avids before but after bleeding they have been solid. If you are having problems I would really just call SRAM. They have some of the best customer service I have ever dealt with.
     
    #4 -   Feb 2, 2008
  5. OGRipper

    OGRipper Turbo Monkey

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    NORCAL is the hizzle
    I own juicy's, ultimates, and codes. All of the m do this every now and then. It's never been an issue for me on the trail. I don't know for sure but if I had to guess I'd say it's air trapped in the caliper. I dunno, maybe try running through the bleeding steps with your bike upside down, but following the directions for the lever angle...?
     
    #5 -   Feb 2, 2008
  6. DHS

    DHS Friendly Neighborhood Pool Boy

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    yes. i've come across this problem before. there's still air in the fluid itself.
    maybe try new brake fluid completely.

    actually, if you like, i think i still have a small bottle of "avid" branded fluid you could try.

    or you could get a RA from sram, and if they are under a year, can go under warranty. but if you followed the sram tech video. there's nothing else they can tell you to do
     
    #6 -   Feb 2, 2008
  7. kellyn7

    kellyn7 Monkey

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    I too was having the same problem not that long ago. Anytime I stood the bike up on its rear wheel and pump the brake it would result in loss of all power after 4 or 5 pumps. It took me awhile but I figured it was due to poor brake bleeding done by me. Anytime I bleed my brakes now I do it with the bike standing on its rear wheel and I always make sure to gently force fluid back into the brake system after the air has been pulled out. Now when I finish my brake bleeding I always stand it up on it rear wheel and pump the brakes. This is my determining factor on whether or not I got a good bleed or not. If the brake is firm after several pumps its all good otherwise sh*t, it's back to square one.
     
    #7 -   Feb 2, 2008
  8. Transcend

    Transcend My Nuts Are Flat

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    Shimanoes do the same thing, john. Even with a perfect bleed, when you flip it over it's mushy as hell and you have to pump it back up by flicking the lever a few times.

    I gave up trying to figure out what it is, because it is easy to get rid of and only happens when stored upside down.
     
    #8 -   Feb 2, 2008
  9. Jonny5

    Jonny5 Monkey

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    There is air still in the lever. DO the syringe fill and air empty thing and just put in on the lever. Tap the lever with a something plastic and do the push pull thing a few times.
     
    #9 -   Feb 2, 2008
  10. ÆX

    ÆX Turbo Monkey

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    after i blead i take the res cap off then
    put the levr hight hose low till almost all of the
    fluid in the res is out, but enought to still not
    suck air in.

    now with the levet in the position hose low caliper
    hanging on the ground squeze the lever till you see
    all air come out. turn horizontal to leval fluid and over
    fill to surface tention. put res cap on.

    worked for me. rock hard.
     
  11. DHS

    DHS Friendly Neighborhood Pool Boy

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    can you explain this a little bit better?

    do you actually take the whole lever off from the clamp. to get access to the resi, or what?
    i was thinking that, like shimanos or hopes, sometimes you can just top off the fluid.
    but avids, have such hard to reach resi top cap.
     
  12. ÆX

    ÆX Turbo Monkey

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    resi cap come off.
    then angle @ about 45 deg, not so far you scavenge where the fluid goes
    in to the cylinder. but it does empty out about 2/3 of the fluid.

    pull lever slowly and you will see air come out of the cylinder.

    do all this after you do hose bleed. don't need a lever blead
    this does that for you.

    then put lever horz to cap on resi and fill as much as possible.
     
  13. SK6

    SK6 Turbo Monkey

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    Shut up and ride...
    Send them back. They're a defect. Trust me. Save yourself a bunch of frustration and send them back.
     
  14. .Pit Steelers.

    .Pit Steelers. Nostradumbass

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    You sure about that, because one of my 08 7's has this problem but it has it all the time.
     
  15. SK6

    SK6 Turbo Monkey

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    That's what I was told.
     
  16. John P.

    John P. Turbo Monkey

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    Just got off the phone with Avid/Sram. The guy I spoke with was very nice, but he wasn't much help, saying he'd have to see exactly what I was doing to diagnose the problem. Most of his advice consisted of walking through the bleed process step-by-step, which I already had done. He said the problem was due to some sort of vaccuum that exists within the system, and mentioned that problem should correct itself once the bike is upright again and I pumped the levers. This was not correcting it for me, but I had a bit of a light-bulb moment after I got off the phone -- I decided to pump the brakes a bit while the bike was tipped up on it's FRONT wheel, and this actually helped a bit. Weird.

    Now, granted, the brakes aren't back to feeling as great as they did before all this, but at least I have some technique to get my brakes working again if I'm ever out on a ride and run into this problem. For now, though, looks like I'm looking at another bleed, and I'll probably try BCD's advice.

    Chime in if you have any other insight,

    --JP
     
  17. ÆX

    ÆX Turbo Monkey

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    for me i did the perfect sram bleed and them found
    more air doing it my way. give it a try it works.