UN55 square taper bottom bracket , non drive side metal cup hits up against something
07-21-18, 11:11 AM
#1
Senior Member
Thread Starter
UN55 square taper bottom bracket , non drive side metal cup hits up against something
Hi ,
This is strange .
I have a un55 that i am trying to install into a bike .
BB shell width is 68 and bike bottom bracket width is 68 also checked with Calipers .
The non drive side cup will install fine on its own but if installed after the drive side part has been installed it cant fully thread in .
Likewise the non drive side part installs all the way in BUT if the non drive side cup is in there first then it will not thread in all the way .
Do I need to sand down the cup or something ?
J
This is strange .
I have a un55 that i am trying to install into a bike .
BB shell width is 68 and bike bottom bracket width is 68 also checked with Calipers .
The non drive side cup will install fine on its own but if installed after the drive side part has been installed it cant fully thread in .
Likewise the non drive side part installs all the way in BUT if the non drive side cup is in there first then it will not thread in all the way .
Do I need to sand down the cup or something ?
J
07-21-18, 11:18 AM
#2
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Does the NDS cup slide onto the cartridge body easily? If not, check for interference there.
If that's good then install the DS partway, then thread in the NDS cup partway. Continue to thread each side in a few turns at a time until seated.
If there is stiff interference when installed, possible that the threading on the BB itself is offset in some way.
If that's good then install the DS partway, then thread in the NDS cup partway. Continue to thread each side in a few turns at a time until seated.
If there is stiff interference when installed, possible that the threading on the BB itself is offset in some way.
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07-21-18, 11:41 AM
#3
Really Old Senior Member
IF this has the plastic NDS "cup", I just screw that all the way in first and then crank on the metal DS cup until seated.
When removing, I start with the metal cup.
The one least likely to break gets the major torque.
If these are both metal, you probably need a spacer.
When removing, I start with the metal cup.
The one least likely to break gets the major torque.
If these are both metal, you probably need a spacer.
Last edited by Bill Kapaun; 07-21-18 at 11:47 AM.
07-21-18, 03:04 PM
#4
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Is there perhaps a bolt holding a cable guide to the bottom bracket shell that protrudes into the shell enough to interfere with the cups?
If so loosen the bolt enough to install the cups, then re-tighten it after the cartridge is installed. You may need washers or a shorter bolt if you can't turn it in all the way.
If so loosen the bolt enough to install the cups, then re-tighten it after the cartridge is installed. You may need washers or a shorter bolt if you can't turn it in all the way.
07-21-18, 04:46 PM
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Does the NDS cup slide onto the cartridge body easily? If not, check for interference there.
If that's good then install the DS partway, then thread in the NDS cup partway. Continue to thread each side in a few turns at a time until seated.
If there is stiff interference when installed, possible that the threading on the BB itself is offset in some way.
If that's good then install the DS partway, then thread in the NDS cup partway. Continue to thread each side in a few turns at a time until seated.
If there is stiff interference when installed, possible that the threading on the BB itself is offset in some way.
07-21-18, 05:02 PM
#6
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Has the frame been painted recently? It's possible that the BB shell needs to be faced so that the ends are parallel. If they aren't parallel, either cup will thread in fine by itself, but when the NDS cup must fit over the end of the cartridge it isn't perfectly aligned and binds.
Threading both cups partially may eliminate any slight misalignment enough for you to complete the install, but personally I would face the BB shell to eliminate any misalignment.
Threading both cups partially may eliminate any slight misalignment enough for you to complete the install, but personally I would face the BB shell to eliminate any misalignment.
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07-21-18, 05:08 PM
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Isn't this just the non-DS cup just bottoming out on the end of the BB cartridge? That's exactly what it is supposed to do, I believe.
Edit: I have always just threaded the DS in tight, then screwed the plastic non-DS cup until it bottoms out and called it good.
Ben
Edit: I have always just threaded the DS in tight, then screwed the plastic non-DS cup until it bottoms out and called it good.
Ben
07-22-18, 02:08 PM
#8
Senior Member
Thread Starter
Hi Ben I hope your right but usually the NDA cup threads in so that it's lip is flush with edge of the frame . I can still see space and a few threads between frame and NDS cup
07-22-18, 02:29 PM
#9
Senior Member
Thread Starter
Solved ! Thanks folks , I used the NDS cup from the worn BB that I removed . This old NDS cup has no lip and threaded in fully with the new BB in place .
Still strange though
Still strange though
07-22-18, 02:54 PM
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The NDS cup on a BB-UN55 has a lip on it? This is the first time I've heard of this. Typically, the NDS cup does not have a lip, but Googling pictures of the UN55, it seems that some pictures show a cup with a lip and some show a cup without a lip. So are you saying that the UN55 NDS cup was threading in until the lip bottomed out on the bottom bracket shell, and that wasn't threaded in far enough?
07-22-18, 05:37 PM
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There's a 50/50 chance the nds had a burr causing the lips to deadhead. The one is supposed to slip over around the other for a tighter seal. Putting the plastic part outside on a hot day while installing the other part allowed them to slip joint together when i experienced such issue.
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07-22-18, 06:57 PM
#12
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Check this thread: https://www.bikeforums.net/bicycle-m...bracket-3.html
The UN55 cup on the non-drive side has a lip now. Previously it did not.
The UN55 cup on the non-drive side has a lip now. Previously it did not.
