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  1. #1
    Senior Member roadie138's Avatar
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    Help geting 12-27 dura ace cassette in right order

    I just took my 12-27 7800 dura ace cassette off to clean it not sure where the spacers go?Is there any way I can get get the gears turned upside down?Or put it on wrong when I go to put this back on my wheel? Is there a place that shows a diagram of this?
    Last edited by roadie138; 02-22-09 at 01:12 PM.
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    Senior Member Retro Grouch's Avatar
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    Shouldn't be that hard. The cogs won't go on backward due to the pattern of the splines. Most of the spacers are the same so just play with them until the spaces between the cogs look equal.

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    Senior Member roadie138's Avatar
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    Thanks Grouch I will see if I can figure it out. Also when I tighten my cassette how do I know when its tight enough?
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    cab horn
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    Quote Originally Posted by roadie138 View Post
    Thanks Grouch I will see if I can figure it out. Also when I tighten my cassette how do I know when its tight enough?
    Lockrings have a 40nm spec, which to me is way higher than is ever necessary. Don't forget to grease the lockring before putting it on. Go for sensitive tight on the lockring. It isn't rocket science.
    Mes compaingnons cui j'amoie et cui j'aim,... Me di, chanson.

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    Senior Member roadie138's Avatar
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    Ok Thanks operator is General Purpose White Lithium Grease OK?
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    My two cents here. Lithium grease probably would be fine for that but you only need a light smear. I will agree about finding the spacing is easy, just line them up with the biggest gear on the bottom and go from there. I've never taken apart the Dura Ace cassette but other cassettes use spacers between the teeth. Look at it and it's easy to figure out. If there are any indentations around the large hole in the middle, they go down, towards the largest gear. Then just build up like a pyramid.

  7. #7
    sch
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    Since there are indents on the lockring, it is not hard for someone who has not
    tightened one before to get it 'tight' but still have a few thousands play in the
    cogs. A torque fairly close to the suggested 40NM is advisable for that reason.
    A friend put our new 11-28 cassette on a new wheel for our tandem and the
    cogs rattled all day yesterday on the chipseal. You can google a conversion factor to inch #
    or foot # of torque if you don't have a torque wrench and guesstimate by
    looking at your lever arm and the weight applied.

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    cab horn
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    Quote Originally Posted by sch View Post
    Since there are indents on the lockring, it is not hard for someone who has not
    tightened one before to get it 'tight' but still have a few thousands play in the
    cogs. A torque fairly close to the suggested 40NM is advisable for that reason.
    A friend put our new 11-28 cassette on a new wheel for our tandem and the
    cogs rattled all day yesterday on the chipseal. You can google a conversion factor to inch #
    or foot # of torque if you don't have a torque wrench and guesstimate by
    looking at your lever arm and the weight applied.
    That is possible, you'd have to be an idiot to leave it that loose. But I can see how that's possible.
    Mes compaingnons cui j'amoie et cui j'aim,... Me di, chanson.

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    Senior Member roadie138's Avatar
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    OK THANKS guys everythings back together and it seems to work fine.But now I wonder if the cassette is tight enough.After reading other post not getting it tight enough can be a problem.I want to buy a torque wrench would this one work http://www.harborfreight.com/cpi/cta...Itemnumber=239 . Is there any way to convert nm to foot pounds?
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    One N-m = .738 lb-ft so 40 N-m is 29.5 lb-ft or 354 lb-in.

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    While it is possible to overtighten the lockring it is much more common to not tighten enough. Loose cogs can damage the freehub. Rattling is not the only consideration. If you have any doubt about how tight is "tight enough" in this application use a torque wrench.

    Al

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    A schematic is on Shimano's website under tech support, tech documents.
    http://techdocs.shimano.com/media/te...9830608753.pdf

  13. #13
    Senior Member roadie138's Avatar
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    Yea Al I agree when in doubt about how tight is "tight enough" in this application use a torque wrench.
    Went to my LBS today the mechanic showed me how tight he gets them. He says he never uses a torque wrench.And told me he has never had anybody come back and tell him the cassette was loose in the 15 years he's been working on bikes.But it would still be nice to torque it to the manufacture spec.Thanks for the schematic DAN thats exactly what I was looking for.
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