Did I just destroy my brand new Octalink crankset?

Discussion in 'Cycling Equipment' started by fbagatelleblack, Jun 5, 2006.

  1. fbagatelleblack

    fbagatelleblack New Member

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    Hi All,

    I recently installed a Shimano 105 Octalink crankset with a hollow-spindle Shimano BB. My first attempt at installation was a complete bust - the crankarms were off parallel by 15 degrees or so (DUUUUUR!! Me real good at wrenching!). So I disassembled, lined everything up correctly, and cranked things down again. I cranked pretty hard, but I don't have a torque wrench, so I cannot say that I nailed the torque spec on the head. I am guessing that I overtorqued things a bit.

    Note that I did not grease the spindle. I recently read through:

    http://www.cyclingforums.com/t-212352-15-1.html

    So I realize that spindle-greasing is an issue.

    I went for a ride on Saturday. After about 10 miles, I felt a "click" in the cranks when I really stomped on the pedals in the middle ring. I could not make it click in the big ring. I had just loosened the springs in my SPD pedals, so at first I thought the clicking was coming from my pedals.

    At about 35 miles, the clicking happened every time I accelerated in any chainring. By now, I had backed way off on pedal pressure, and I limped home using as little force as possible.

    I put the bike in the stand, tightened the non-drive side BB retaining ring, and checked the crank bolts. The drive-side crank was completely loose! I then really cranked down on the crank bolts with a cheater tube to give me leverage. I took it for a quick test ride. I live on a steep hill so I can really crank on the pedals in a short amount of time. After a few bursts of uphill acceleration, I checked the crank bolts again. The drive side was loose again! I tried to take the drive side crank arm off, but it was on solidly and I do not have the plug you need to use with the crank puller. I tapped, very very extremely gently, with a rubber mallet at a few points on the small chainring, to see if I could loosen the crankarm. Nope.

    So I REALLY cranked on the crank bolts, and test rode again. Same deal.

    Next, I used blue Loctite on the crank bolts. I test rode again. This time, the bolts did not loosen up. However, if the crankarm has moved up marginally on the spindle and it's just the Loctite holding the crank bolt in place, I haven't really solved the problem. If I buggered up the taper on the BB spindle (do the Octalinks even have "tapers??") then I'm probably fighting a loosing battle at this point.

    Any help from the experts would be much appreciated.

    Yours,

    Forbes "Square Tapers Are My Friend" Bagatelle-Black
     
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  2. DiabloScott

    DiabloScott New Member

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    Yes, sounds a lot like you ruined your crank.
     
  3. fbagatelleblack

    fbagatelleblack New Member

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    If this is the unfortunate case, more questions arise:

    1. Did the ruination occur due to my original misalignment? Or was it from riding the crank loose? Educated guesses would be appreciated.

    2. Is the BB spindle likely to be okay? Did I just bugger up the aluminum on the crankset? If so, I can order a new crank (which I got on a screaming sale) and keep the chainrings, which are worth quite a bit more than what I paid for the crankset. I suppose I will have to disassemble things and check the BB spindle before I know for sure.

    Thanks,

    FBB
     
  4. Mansmind

    Mansmind New Member

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    Sounds like to me you may have OVER tightened the bolts in the first place. Perhaps you have partially stripped the threads on one side? It doesn't make sense that it would continually loosen up...unless perhaps you don't have the crank arm seated on the splines well enough.
     
  5. badkarma

    badkarma New Member

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    Could it be you just ruined the bearings on the BB?
     
  6. DiabloScott

    DiabloScott New Member

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    The damage comes from riding the crank loose. The original misalignment (arms not being 180° from each other) had nothing to do with it... you were just off by one spline. (If I'm right...)the problem was when you reinstalled the arm you were off by maybe 1/2 a spline which maybe felt tight but as you rode they got looser and looser and you buggered up the spline interface in the crankarm. May or may not be obvious when you take it off and look... it doesn't take much. Crank failures are not pretty - don't ride it or at least take it VERY easy.

    The spindle is probably fine but if it looks damaged, bent, or gouged, replace it as well.
     
  7. curby

    curby New Member

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    this couldn't be a spline version1 vs. spline version2 issue?

    (no octalink experience here, just curious)
     
  8. 62vette

    62vette Well-Known Member

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    It's probably the thread in the BB spindle that has been stripped, and possibly the splines as well. You'll need to get a crank puller and remove the crank arms to assess the damage to the splines on both the BB and crank. At the least you may have to replace the BB and depending on damage the crank arm as well.

    See http://www.parktool.com/repair/readhowto.asp?id=94 for BB servicing tips, and don't forget to grease.
     
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