Drive side on cartridge BB loosening
09-29-13, 08:24 AM
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Drive side on cartridge BB loosening
I bought a UN-55 BB a few days ago and installed it on my bike that afternoon. I torqued it down, and reinstalled the crankset with plenty of grease. I went for a 20 mile ride yesterday and the drive side cup was loose by about 0.5 mm. I pulled the cranks and disassembled the bb. Nothing was wrong; the threads were fine: greased and clean. I have had cartridge BBs loosen on this bike before, but torquing it down hard solved that. I guess I didn't torque it hard enough this time. Anyway, I reassembled it all with grease and this time I used Teflon tape on the drive side. I have a feeling that it's solved now, but just in case it doesn't hold, what would you suggest I do to keep it from loosening again?
Note: I used grease on ALL threads, tightened to spec, and have installed the same model BB on other bikes I own and never had any problems with.
Note: I used grease on ALL threads, tightened to spec, and have installed the same model BB on other bikes I own and never had any problems with.
09-29-13, 09:56 AM
#2
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not tight enough I'd say.. got the spline tool that you can put a socket wrench -breaker bar on
or the 1/2" drive torque wrench?
or the 1/2" drive torque wrench?
09-29-13, 10:05 AM
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This is typically the result of not having both sides of the BB torqued or tightened enough. If it persists after tighting Shimano specs that you use a small amount of blue loctite on each side.
09-29-13, 10:24 AM
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I probably torqued it past spec yesterday actually. Rode around a little bit and it's hasn't loosened butninwont know if it's tight enough until after a few days/weeks of use.
I will try loctite if it doesn't hold. Is there any specific kind I should use?
I will try loctite if it doesn't hold. Is there any specific kind I should use?
09-29-13, 11:30 AM
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"I probably torqued it past spec yesterday actually."
How do you know this; did you use a torque wrench or just guess? Shimano specifies 36 to 51 foot-lbs which is a surprisingly large amount of torque. Most people undertorque large fasteners and overtorque smaller ones, so you may have guessed wrong.
How do you know this; did you use a torque wrench or just guess? Shimano specifies 36 to 51 foot-lbs which is a surprisingly large amount of torque. Most people undertorque large fasteners and overtorque smaller ones, so you may have guessed wrong.
09-30-13, 08:26 AM
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Facing the BB might help; I can see a BB with an out-of-square edge needing extra torque.
If the BB stiffens up a bit when you crank it up hard this is almost a cert.
If the BB stiffens up a bit when you crank it up hard this is almost a cert.
10-01-13, 05:01 AM
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Tubular glue.
Well, that's what we used to use. Ha!
Well, that's what we used to use. Ha!
10-01-13, 01:37 PM
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I learned recently that cross threading them in means they'll never come loose. In fact, they're nearly impossible to remove.
