Bottom Bracket gets loose every 3 or 4 turns
05-21-21, 08:23 AM
#26
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If the threads have gotten sloppy, sometimes a few wraps of teflon plumber's tape around the threads can be enough to hold the cup securely. Failing that, a threadless cartridge can be a cost-effective fix. If the shell is English or metric thread (French or Swiss), it can be reamed and tapped with Italian thread and a standard Italian thread bottom bracket or cartridge can be installed.
05-21-21, 09:23 AM
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Well, everybody was pretty much spot on about this! Components pretty much trashed, the worst being the fixed side cup. That cup was not completely loose, but it was not as tight as it should have been it came loose with very little effort. Sure enough, the spindle had been reversed by the LBS, with the short side on the rings. It had caged 9 count bearings, properly installed, with some just falling out of the cages upon disassembly. Good news it the cranks are OK, the BB shell is good with all threads in fine shape.
Debating about trying to stay vintage or just get a cartridge, standard English size and threads, seems to be 124.5mm spindle. I don't think I need to worry about the offset on the spindle since the bike seemed to run just fine with the thing reversed!
Debating about trying to stay vintage or just get a cartridge, standard English size and threads, seems to be 124.5mm spindle. I don't think I need to worry about the offset on the spindle since the bike seemed to run just fine with the thing reversed!
05-21-21, 09:36 AM
#28
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05-21-21, 11:36 AM
#29
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If I could get the assembly and front derailer to work right with everything having needed clearance and the front derailer downshifting well, I would definitely use the short spindle offset on the drive side myself.
But better yet would be a shorter spindle, installed right-side-right.
So was it worn parts that caused it to loosen? No excuse though for a fixed cup not heavily tightened! Maybe the shop didn't even remove the fixed cup and didn't even apply tightening torque to make sure it was tight(?).
Many if not most Japanese bikes I've bought almost certainly did not have their fixed cup tightened securely from the factory. These would not back out while riding, but instead would loosen just enough to go on clicking forever as the fixed cup moved back and forth slightly. Again, this seems almost universal when the bikes started seeing serious use by this lightweight rider. And these were bikes that I bought in little-used condition, not having been serviced ever.
But better yet would be a shorter spindle, installed right-side-right.
So was it worn parts that caused it to loosen? No excuse though for a fixed cup not heavily tightened! Maybe the shop didn't even remove the fixed cup and didn't even apply tightening torque to make sure it was tight(?).
Many if not most Japanese bikes I've bought almost certainly did not have their fixed cup tightened securely from the factory. These would not back out while riding, but instead would loosen just enough to go on clicking forever as the fixed cup moved back and forth slightly. Again, this seems almost universal when the bikes started seeing serious use by this lightweight rider. And these were bikes that I bought in little-used condition, not having been serviced ever.
05-24-21, 09:27 AM
#30
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I've one last query for you fine folks, my parts are coming in and i am wondering how much to lube the threads when I put stuff back together. It seems like things need to be tight and stay tight, but at the same time I want to be able to get this apart again in the future. My new crank are bolts look like they have a drop of blue Loctite already in place...
05-24-21, 09:56 AM
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I've one last query for you fine folks, my parts are coming in and i am wondering how much to lube the threads when I put stuff back together. It seems like things need to be tight and stay tight, but at the same time I want to be able to get this apart again in the future. My new crank are bolts look like they have a drop of blue Loctite already in place...
Just put some on both mating parts and any excess just squishes out, no biggie.
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05-24-21, 10:29 AM
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An observation that probably doesn't apply, but still ...
The direction of the forces generated by pedaling are reversed by the ball bearings. This means the forces on the cup are generated in a clockwise direction on the left, NDS side and counterclockwise on the DS. So, most of the bottom bracket manufacturers and framebuilders use a standard of right hand, self-tightening threads on the left, NDS and left-hand threads on the right.
But! If the bearings aren't doing their job of spinning freely, they aren't reversing the force direction and guess what? Your mighty quads are now unscrewing the cups!
The direction of the forces generated by pedaling are reversed by the ball bearings. This means the forces on the cup are generated in a clockwise direction on the left, NDS side and counterclockwise on the DS. So, most of the bottom bracket manufacturers and framebuilders use a standard of right hand, self-tightening threads on the left, NDS and left-hand threads on the right.
But! If the bearings aren't doing their job of spinning freely, they aren't reversing the force direction and guess what? Your mighty quads are now unscrewing the cups!
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