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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 05-18-09, 06:12 PM   #1
robatsu
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Loose Bottom Bracket Threading

I have a 1981 Fuji Gran Tourer that I've been chasing down some knocking/clicking on for a long time. Pretty much been over the whole bike, with different wheelsets, cranks, bb's, pedals, etc, and everything points to some issue with the bottom bracket shell.

What the problem appears to me is that the adjustable cup side (I'm running loose bearing bb compatible w/old Sugino Mighty Tour crank) threading is pretty loose. It doesn't appear damaged or worn, maybe just somebody was being a little enthusiastic at the factory. The adjustable cups do actually thread in, but even when just about threaded all the way in, you can still get a pretty perceptible jiggle.

This is definitely the threads, not the cup, since it is the same w/any cup, and I've tried about three or four.

The fixed side is fine.

I've tried teflon wrap, tons of grease, torque, etc, and this does mitigate the issue, but not to a level of acceptability. The bottom bracket is prone to start knocking w/out warning, easily loud enough to be heard by riding companions, and can be felt through the pedals. This is pretty consistent despite trying different bb's, cranks, caged/uncaged bearings. The only thing that had any effect was tons of teflon/grease/torque.

The interesting thing is that it is always fine, silky smooth, at the beginning of a ride, takes about 3-5 miles to get started, but once it does, it is pretty constant.

Well, I want to solve this problem, since I otherwise adore the bike. I'm not crazy about a cartridge bb, pretty tough to find one for running a Sugino Mighty Tour as a triple, and it is unclear whether I would have a similar problem with the mounting ring on the non-drive side with a cartridge.

So I'm throwing myself on the mercy of the court, I'm an ok mechanic, but I'm at the end of my rope - this bike was meant to replace my previous daily rider, so I'm looking for a very reliable fix, one that I can be comfortable taking off on day trips, pulling trailers, commuting, etc.
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Old 05-19-09, 09:00 AM   #2
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are you using a locking ring on the (adjustable) cup ? your post doesn't said anything about it ? with all cups and cones set up (hubs,BB, headsets ) use some kind of locking nut or ring.if you don't have one go to your lbs and ask for one. there alway some play in these units.
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