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Old 09-26-06, 01:33 AM   #1
rollsroyce
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BB shifted over? Came loose?

I've recently installed a new Campy Centaur bottom bracket into an 80s italian frame. After a bit of riding, I noticed that the entire BB shifted over towards the drive side. To clarify, the left side has threaded further into the BB shell and the right side, the drive side, has unthreaded quite a bit. So much so that I cannot shift to the outer chainring. Is this just a result of not tightening the drive side enough? Is this common? Thanks.
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Old 09-26-06, 02:05 AM   #2
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I've heard about this problem with Italian BBs, but having ridden tens of thousands of kilometers on different frames with Italian BBs never experienced it. I suspect that the BB in fact wasn't tightened properly.
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Old 09-26-06, 06:00 AM   #3
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It's almost a given that the drive side cup wasn't tightened enough when installed. What you've experiences is the classic Italian bb untreading from inadequate installation torque.

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Old 09-26-06, 06:56 AM   #4
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many people would also suggest using a mild form of loctite (I use 242, which is blue but comes in a red bottle. Confusing) on non-reverse-threaded driveside BB cups. I always do and have not had a problem with Italian BBs backing out since I started. Proper torque is part of the solution, but not always enough.

- Joel
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Old 09-26-06, 10:20 AM   #5
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The older BBs have a standard thread on both sides. That means that one is prone to backing out. Modern BBs use a reverse thread on that side. Be sure to torque correctly (as in use a torque wrench), and if necessary use Loctite (blue is good).
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Old 09-26-06, 07:05 PM   #6
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I'm pretty sure modern and older Italian BB threading is the same. 70mm shell * 36mm * 24tpi, right hand thread both sides.

- Joel
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Old 09-27-06, 09:45 AM   #7
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I think you're right, as per this table.
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Old 09-27-06, 09:48 AM   #8
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It happened to me on my '04 Colnago C50 with Record bottom bracket. I cured it with my 36 inch 1/2" drive Craftsman beam torque wrench.

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Old 09-27-06, 03:01 PM   #9
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Quote:
Originally Posted by tomacropod
I'm pretty sure modern and older Italian BB threading is the same. 70mm shell * 36mm * 24tpi, right hand thread both sides.

- Joel
That's correct. I suppose what DMF was referring to was that older Italian frames were all Italian threaded while a lot of newer Italian frames have gone to English threading.
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