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Shimano UN26 Cartridge BB assembled wrong?

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Shimano UN26 Cartridge BB assembled wrong?

Old 03-30-20, 10:02 PM
  #1  
Miele Man
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Shimano UN26 Cartridge BB assembled wrong?

I have this Shimano square taper UN26 cartridge bottom bracket that I think might have been assembled wrong.

It's the drive side part that has me thinking that. The flats of the square taper end BELOW the drive side cup. Thus when I go to put a crank arm on it the crankarm goes all the way to the cup. Interestingly enough the exact same crankarm only goes partway onto the the non-rive side spindle.

Here are two images of the bottom bracket that I hope shows the drive side spindle okay for analysis by you folks.




So, am I correct in thinking that this unit was wrongly assembled?

Thanks and cheers
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Old 03-31-20, 05:14 PM
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Is the drive side cup seated all the way onto the cartridge body? I looks like it can be slid on further.
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Old 03-31-20, 06:13 PM
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Originally Posted by Bill Kapaun
It IS the body.
I don't think you understood what I was asking. You said; " The flats of the square taper end BELOW the drive side cup." I asked if that drive side cup pushed down over the cylindrical body as far as it will go? If not, it will interfere with the crank arm as you noted.

Some Shimano cartridge bottom brackets have the drive side cup as an integral part of the cartridge body and the NDS cup is a slip fit over the NDS end. Others have both cups as slip fits over the cartridge body. Which type is yours as I can't be sure from the photos?
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Old 03-31-20, 07:01 PM
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I agree with HillRider that the DS cup isn't quite driven down as far as it will go. It looks to be a separate piece from the photo.
I would take the correct diameter socket, put it over, and try tapping it down.
At minimum measure where 73mm falls from the DS cup edge and see if it seems "too long"
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Old 03-31-20, 07:02 PM
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I see a BB for a 73mm width shell with a 110mm spindle. That's a pretty off-the-wall setup. What kind of bike and crankset is this for?
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Old 03-31-20, 07:22 PM
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Originally Posted by Jeff Wills
I see a BB for a 73mm width shell with a 110mm spindle. That's a pretty off-the-wall setup. What kind of bike and crankset is this for?
I have no idea what bike that cartridge bb was intended for. I was going to use it on a single speed. The drive side cup looks to be integral to the shell. If I had a big enough vice I'd try using it and spacers to push the non-drive side part of the spindle further towards th right side.

I've never seen another cartridge bb like this one.

Cheers
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Old 03-31-20, 07:44 PM
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Originally Posted by Jeff Wills
I see a BB for a 73mm width shell with a 110mm spindle. That's a pretty off-the-wall setup. What kind of bike and crankset is this for?
Yes - this is a really narrow BB - the narrowest in a Shimano 68mm shell is 107 so this is equivalent to a 105 spindle length in a 68mm shell. The only way to get this narrow is to make the cranks get very close to the shells. Put on the cranks and I bet they almost touch the shells and if your cranks tapers are worn they may even touch and scrape.
Here is a pic of a 103mm spindle and you can also see the flats are under the shells.
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Old 03-31-20, 09:24 PM
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Thanks all and especially bluehills3149 for the image that shows this is not a wrongly assembled bottom bracket.

Cheers
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Old 03-31-20, 09:26 PM
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Originally Posted by Miele Man
I have no idea what bike that cartridge bb was intended for. I was going to use it on a single speed. The drive side cup looks to be integral to the shell. If I had a big enough vice I'd try using it and spacers to push the non-drive side part of the spindle further towards th right side.

I've never seen another cartridge bb like this one.

Cheers
"Normal" English BB width is 68mm. A 73 mm width would be for a mountain bike, and 110mm length spindle indicates it's for "low profile" crankarms, perhaps from the mid-'90's. Again: what cranks are you planning using with this BB?
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Old 03-31-20, 09:40 PM
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Originally Posted by Jeff Wills
"Normal" English BB width is 68mm. A 73 mm width would be for a mountain bike, and 110mm length spindle indicates it's for "low profile" crankarms, perhaps from the mid-'90's. Again: what cranks are you planning using with this BB?
I'm building a couple of bikes and using parts for them from my scrap boxes. I was surprised when the crank arm on this bottom bracket went right to the end of the taper on the drive side but not on the non-drive side. I 'll be using different bottom brackets on those two builds.

Cheers
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Old 04-01-20, 09:06 PM
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Originally Posted by Miele Man
I'm building a couple of bikes and using parts for them from my scrap boxes. I was surprised when the crank arm on this bottom bracket went right to the end of the taper on the drive side but not on the non-drive side. I 'll be using different bottom brackets on those two builds.

Cheers
Yeah, I have a half-dozen BB's in my boxes o' carp. A couple are useless- one squeaks in every bike I've put it in and another is Campy/SKF which I don't have a tool for.
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