Depressed
- Thread starter Mr Toad
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Mr Toad
Retro Guru
Re:
Hi
No clue what the second BB is I'm afraid , original 1992 gt avalanche I suspect ( deore Dx ? ) one side is plastic I think , other side appears to be metal ,I don't have the frames here at the moment to look
Marin frame is Tange Prestige Ultimate Ultrastrong
Gt frame I'm not sure , some sort of chromoly steel I suspect ?
Thanks
H
Hi
No clue what the second BB is I'm afraid , original 1992 gt avalanche I suspect ( deore Dx ? ) one side is plastic I think , other side appears to be metal ,I don't have the frames here at the moment to look
Marin frame is Tange Prestige Ultimate Ultrastrong
Gt frame I'm not sure , some sort of chromoly steel I suspect ?
Thanks
H
Re:
I think Shimano UN cartridge bottom brackets have standard industrial bearings pressed into each end, something like this:
You should be able to pop off the plastic cover with a small screwdriver, or knife blade. Under the cover you should see the ball bearings in a holder, something like this:
Or the holder may be plastic. In any case if you can break the holder so that the balls are loose, there should be enough room to allow all the balls to go to one side and the inners come out of the outers along with the square taper spindle. You may then be able to drift out the outers with a punch, or old screwdriver, leaving just the threaded part and central portion of the cartridge, which you may then be able to saw through to the BB shell, perhaps in two places so that you can crush the threaded part where you've sawn through it, get hold of it and pull it out. If you cut a couple of slots in the BB threads, it shouldn't be a complete disaster and there should be plenty of thread left for the new BB.
I haven't tried this and it's just and idea, so I may be talking out of the top of my hat.
I think Shimano UN cartridge bottom brackets have standard industrial bearings pressed into each end, something like this:
You should be able to pop off the plastic cover with a small screwdriver, or knife blade. Under the cover you should see the ball bearings in a holder, something like this:
Or the holder may be plastic. In any case if you can break the holder so that the balls are loose, there should be enough room to allow all the balls to go to one side and the inners come out of the outers along with the square taper spindle. You may then be able to drift out the outers with a punch, or old screwdriver, leaving just the threaded part and central portion of the cartridge, which you may then be able to saw through to the BB shell, perhaps in two places so that you can crush the threaded part where you've sawn through it, get hold of it and pull it out. If you cut a couple of slots in the BB threads, it shouldn't be a complete disaster and there should be plenty of thread left for the new BB.
I haven't tried this and it's just and idea, so I may be talking out of the top of my hat.
Mr Toad
Retro Guru
Re:
Thanks
This is all very new to me , in my youth I just rode the bikes lol , I was never particularly mechanically minded.
Nothing has changed , which is why I was filled with such dismay when the bike shop said they were all out of ideas ! I've still no idea , I just would like a nice stable of my bikes I lusted after when I was young in my garage.
I've got no idea how bottom brackets go in , or come out lol :facepalm:
Or how to get seized ones out either.
I've got all the time in the world to get them out , there's no rush , I just don't want to damage the frames in the process.
Thanks
This is all very new to me , in my youth I just rode the bikes lol , I was never particularly mechanically minded.
Nothing has changed , which is why I was filled with such dismay when the bike shop said they were all out of ideas ! I've still no idea , I just would like a nice stable of my bikes I lusted after when I was young in my garage.
I've got no idea how bottom brackets go in , or come out lol :facepalm:
Or how to get seized ones out either.
I've got all the time in the world to get them out , there's no rush , I just don't want to damage the frames in the process.
integerspin
Senior Retro Guru
Re:
I made cutter to to remove the part of the cup that retains the cartridge[ mine were ali], then it was simple enough to remove the cups. If you don't get any where let me know.
That's pretty much it.xerxes said:You may then be able to drift out the outers with a punch, or old screwdriver, leaving just the threaded part and central portion of the cartridge, which you may then be able to saw through to the BB shell, perhaps in two places so that you can crush the threaded part where you've sawn through it, get hold of it and pull it out. If you cut a couple of slots in the BB threads, it shouldn't be a complete disaster and there should be plenty of thread left for the new BB.
I haven't tried this and it's just and idea, so I may be talking out of the top of my hat.
I made cutter to to remove the part of the cup that retains the cartridge[ mine were ali], then it was simple enough to remove the cups. If you don't get any where let me know.
Your GT will almost certainly have a Shimano UNxx sealed cartridge BB. Shimano sealed cartridges BBs do not use
industrial cartridge bearings as we know it and like the Royce one.
However xerxes is definitely on to a possible way to get it out. Take a good look here to see how to pull the
Shimano BB to pieces:
viewtopic.php?t=178735
You can take them to pieces with very little tools, quickly and easily.
Once done, you could use a number of options like heat from the inside or a milling maching or put a hacksaw blade
through the hole and carefully cut the cartridge out. I have never done this method as I've never had a really
stubborn BB which required this alternative route.
Hope it helps, but what exactly did the LBS do / not do?
industrial cartridge bearings as we know it and like the Royce one.
However xerxes is definitely on to a possible way to get it out. Take a good look here to see how to pull the
Shimano BB to pieces:
viewtopic.php?t=178735
You can take them to pieces with very little tools, quickly and easily.
Once done, you could use a number of options like heat from the inside or a milling maching or put a hacksaw blade
through the hole and carefully cut the cartridge out. I have never done this method as I've never had a really
stubborn BB which required this alternative route.
Hope it helps, but what exactly did the LBS do / not do?
Re:
Get penetrating oil down there for a few weeks a few times at least daily spraying in via the lowest bottle cage hole on the seattube. Will make a massive difference.
Heat will help and if you spread it around won't damage the paint too bad if at all.
Had to use heat on my kili e stay.
Get penetrating oil down there for a few weeks a few times at least daily spraying in via the lowest bottle cage hole on the seattube. Will make a massive difference.
Heat will help and if you spread it around won't damage the paint too bad if at all.
Had to use heat on my kili e stay.
Re:
That's funny, I was looking for pictures of a disassembled UN5x on Google, but nothing came up. So it's essentially the same as an industrial bearing, but the ball bearings run directly in grooves in the outer casing and the square taper spindle itself.
I've got a UN72 in one bike and a UN54 in another. I'll have a go at taking one apart myself when one finally wears out, but they last for absolutely ages, so that may be several years at my current mileage.
Breaking the cage/holder so that the balls can all bunch up to one side should be enough to allow the spindle to come out, because that's how it gets in there in the first place.
https://www.youtube.com/watch?v=eGyoMuE4gDQ
That's funny, I was looking for pictures of a disassembled UN5x on Google, but nothing came up. So it's essentially the same as an industrial bearing, but the ball bearings run directly in grooves in the outer casing and the square taper spindle itself.
I've got a UN72 in one bike and a UN54 in another. I'll have a go at taking one apart myself when one finally wears out, but they last for absolutely ages, so that may be several years at my current mileage.
Breaking the cage/holder so that the balls can all bunch up to one side should be enough to allow the spindle to come out, because that's how it gets in there in the first place.
https://www.youtube.com/watch?v=eGyoMuE4gDQ
SeeingisBelievingGTMuseum
Old School Grand Master
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Time to find a new bike shop....
Time to find a new bike shop....
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