Nexus 8 rear sprocket replacement

Discussion in 'General Cycling' started by Jim, Sep 6, 2011.

  1. Jim

    Jim Guest

    I am having a problem with what I thought would be a straightforward
    job. I have replaced the rear sprocket on my hub geared bike, but I
    can't reassemble it properly.

    I am unable to lock the cassette joint with the driver cap in place.

    http://www.sheldonbrown.com/nexus8/pages/06.htm

    If I use the driver cap, despite it being thin, it raises the cassette
    joint enough so that when I try to lock the latter, not only does it
    fail to lock but it also turns the axle, sprocket and torque arm.

    I have therefore removed the driver cap, put it aside and locked the
    cassette joint, before returning the wheel to the frame. Now it is
    hard to fit the gear cable. This is because both the cable locknut and
    the sight glass for aligning the two yellow marks in 4th gear have
    rotated maybe 45 degrees clockwise from their normal position. They
    seem to be locked in place by the torque bar (?) which is fastened to
    the frame on the non-drive side.

    When I connected the cable the shifter wasn't able to click into many
    gears, and it required more force than normal. The yellow alignment
    marks did not match in any gear.


    I would appreciate any comments or suggestions as to what I have done
    wrong and how I might be able to fix it. I am not a good mechanic, so
    my error(s) could be very basic.

    I do not have access to a competent mechanic in the foreseeable
    future.
     
    Jim, Sep 6, 2011
    #1
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  2. Jim

    Tosspot Guest

    Ok, I'm quite pissed atm, but I do know what you're on about, I had
    trouble replacing one as well.

    When I was doing it, the red marks indicated can line up in a 'wrong'
    position, so you think you are doing it ok but you're not.

    In particular everything must be seated when trying to put on the
    cassette joint ring. The Cassette joint I found could go on upside down
    and then the joint ring wouldn't fit. It isn't help by the puller and
    bracket rotating! So, the driver cap will fit, but it's an art to get
    the cassette on, you *will* know when it's correct, it will all sit down ok.

    Sorry I can't explain better, it took me 45 minutes of messing about to
    get it right. I can do it every time now, but then I've done it right
    once :-(

    Btw, you know when you have it because the locking ring will lock down
    with nothing moving, but I guess you know that by now.
     
    Tosspot, Sep 6, 2011
    #2
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  3. Jim

    Jim Guest


    "With toss-pots still had drunken heads,
    For the rain it raineth every day."




    I've had another go, but I just can't get the the casstte joint to
    settle down far enough for the lock to work, with the driver cap in
    place, no matter what position the red dots are in.

    It looks like I'll only be able to use this bike in 1st gear with the
    cable detached for the foreseeable future. :(
     
    Jim, Sep 11, 2011
    #3
  4. Jim

    Tosspot Guest

    Ok, what I will try and do is pop off the back wheel in the next week
    and have a look at it and ppost pictures.

    I'm still sure there is nothing wrong, it was a right pig before I
    managed it and I'm still not sure exactly how it goes, I'm just careful
    to note the orientation when I remove it. 'Course, when I'd just built
    the wheel I didn't have that option and it must have taken over 1/2 hour
    messing about to get it seated correctly.
     
    Tosspot, Sep 11, 2011
    #4
  5. Jim

    Jim Guest

    Thank you, I would very much appreciate it. It would be particularly
    interesting to see how the driver cap sits on the sprocket stop ring.

    I'm starting to think about getting a second wheel built up with the
    same hub system so that I can stay on the road when I get myself into
    this kind of difficulty (its not the first time). It might not be easy
    though because a quick look on SJS website shows that the part numbers
    have changed since I bought mine 5 years ago. The spare wheel would be
    expensive so not worth ordering unless I could be certain it would
    slot straight in without any hassle.
     
    Jim, Sep 13, 2011
    #5
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