Avid Juicy5 - free play

The Rookie
The Rookie Posts: 27,812
edited March 2011 in MTB workshop & tech
I have some used J5's on my MTB, however the pads on the front retract back from the disc a long way meaning that a lot of lever movement is taken up just getting them to settle on the disc and I'm worried it won't be long before I run out of travel. They don't need bleeding as the pads move as soon as the lever does, its just too much travel before they are on the disc.

I've tried an elastic band round the lever/bars overnight, that made it better for a day, now they have slunk back, so how do I 'pursuade' them to stay a bit closer? Seems like my pistons have too little friction!

Simon
Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.

Comments

  • nicklouse
    nicklouse Posts: 50,675
    adjust the reach of the lever out (away from the bar) and use for some time. this some how helps reset the pistons faster.

    other wise wheel off and pull the lever not too much just to get them to sit out a bit.

    normal warnings about pistons popping out.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • The Rookie
    The Rookie Posts: 27,812
    OK thanks NIck, I didn't think the adjuster would help (except delaying running out of travel - :D - so will try that.

    Simon
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • diy
    diy Posts: 6,473
    do a lever only bleed with the pad spacer in. This should get a bit more fluid in the system and take up the slack.

    the J5s don't have a contact adjuster do they? Otherwise that is the first thing to try.
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  • The Rookie
    The Rookie Posts: 27,812
    No contact adjuster no.

    Its been bled with the pad spacer in, I did another bleed, but nothing in there, all air is out, I could only get more fluid in by doing a bleed against the disc (no pad spacer), but that will mean its overfilled come pad change time.

    Simon
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • gtd.
    gtd. Posts: 626
    nicklouse wrote:
    Other wise wheel off and pull the lever not too much just to get them to sit out a bit.

    normal warnings about pistons popping out.

    I've done that before using a wallpaper scraper to stop the pistons coming all the way out it kept them pretty centralised too. works well with the hope and hayes brakes I've tried it with.
    Mountain: Orange Patriot FR, SubZero & Evo2LE.
    Road: Tifosi Race Custom.
    Do it all bike: Surly Disc Trucker 700c/29er
  • diy
    diy Posts: 6,473
    The Beginner wrote:
    No contact adjuster no.

    Its been bled with the pad spacer in, I did another bleed, but nothing in there, all air is out, I could only get more fluid in by doing a bleed against the disc (no pad spacer), but that will mean its overfilled come pad change time.

    Simon

    nah - just open the bleed screw when you need to change the pads and let the excess out. I'm not suggesting a bleed to get the air out, I'm suggesting a bleed to increase the fluid in the system and improve bite.
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  • The Rookie
    The Rookie Posts: 27,812
    OK, so not a bleed at all (as in bleeding air out - or is that getting the bleeding air out.....) but an 'overfill'.

    The engineer in me finds the idea of just opening the port and spilling offensive, but its an option, I'll try Nicks idea first though.

    Simon
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • nicklouse
    nicklouse Posts: 50,675
    another issue with adding more fluid is that you end up expanding the diaphragm and there is nowhere for the fluid to expand to.

    brakes lock up/rub/drag and most feel in the lever goes.


    the Engineer in me can not explain how the moving of the lever forward works but I found it very use full. :wink:
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Anonymous
    Anonymous Posts: 79,667
    nicklouse wrote:
    the Engineer in me can not explain how the moving of the lever forward works but I found it very use full. :wink:
    Whereas the engineer in me, CAN explain it, but the retarded semi-literate buffoon in me cannot put it into words :oops: :lol:
  • The Rookie
    The Rookie Posts: 27,812
    Sounds like many engineers I work with!

    Simon
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • nicklouse
    nicklouse Posts: 50,675
    Ok been thinking about how it works.

    having the lever forward put pressure on the piston in the Master cylinder.

    this pushes the pistons out a little (or stops them returning quite as much).
    so after some use the seals have settled into the new position.

    dont forget it is the seals that return the pistons to their "set" position. and is there is more friction than normal they dont slip over the piston quite as easily and you have to wait till they get pulled over by reaching max extension (or a force is generated that exceeds the coefficient of friction).

    blah blah blah blah

    or something like that.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • The Rookie
    The Rookie Posts: 27,812
    OK, you sold me on it.....

    Simon
    Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.
  • Phillw454
    Phillw454 Posts: 101
    Hmm maybe getting confused with your issue but if your happy with your leaver position but want the brake to bite earlier try page 8 step 8 of this manual that was linked to me by Nick.

    http://www.sram.com/_media/techdocs/95-5015-009-000.pdf

    Might not be any use but seems to me that might be your hassle, you can make the brake grab earlier/later it seems. Hope it helps.
  • nicklouse
    nicklouse Posts: 50,675
    Phillw454 wrote:
    Hmm maybe getting confused with your issue but if your happy with your leaver position but want the brake to bite earlier try page 8 step 8 of this manual that was linked to me by Nick.

    http://www.sram.com/_media/techdocs/95-5015-009-000.pdf

    Might not be any use but seems to me that might be your hassle, you can make the brake grab earlier/later it seems. Hope it helps.

    you have totally missed the issue.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown

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