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can I disassable a "sealed bearing" BB?

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can I disassable a "sealed bearing" BB?

Old 04-17-21, 08:57 AM
  #1  
pstock
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can I disassable a "sealed bearing" BB?

I am messing around with my stash of bottom brackets.
some of the sealed bearing units feel rough or sticky. so I wondered if I could get inside and relubricated them.
I am starting with a a BB-UN54 (which from it's number I suspect is in the middle of the the range. probably 105 level?)

I can peel off the seals at one end, the NDS end, and the bearings still look shiny.

QUESTIONS:
1. should I be able to similarly remove seals at the DS end and access those bearings? the permantly attached "cup" makes getting a pick or blade in there very difficult.
2. How would they have assembled a BB like this? unless the axle slides out somehow (which I cannot yet set) I cannot figure out how they would have got the axle and the ball bearings into position in the shell.

Peter






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Old 04-17-21, 09:25 AM
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the permantly attached "cup"
Probably the 'cup' is press fitted which from the point of view of home mechanic is a permanent thing, nothing that you could budge.
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Old 04-17-21, 09:30 AM
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Is this a size you can no longer get? Seems like an awful lot of trouble for something that can be had new for $8.00 to $20.00.

Though I to use to have an affliction of trying to repair things that others would throw away. Good experience. Glad I'm over it. <grin>

If it makes you what you are to figure out all about it and repair it, then go for it.
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Old 04-17-21, 10:13 AM
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It's nearly always easier to take stuff apart then reassemble. Something about the laws of entropy Many cartridge like (as opposed to a BB with cartridge bearings) BBs are not really made to be serviceable and can employee assembly methods that include one time fasteners to establish bearing preload. Andy
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Old 04-17-21, 10:22 AM
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well, it all ties back to another question I am facing which is "what length axle BB for what crankset"
I have about.... 15 used BBs in a box. decent but used.
I have about 30 used cranksets in a bin.

I am finding it hard enough to match up what I have. If I am going to start doing trial and error matching of BBs and Cranksets I don't want to start ordering a variety BBs until I get it right.
though I guess I could experiment with my used stuff and once I find the right "fit" I could order a correct fitting BB.

Except, that there is a serious shortage of new bike parts in LBS these days. anyone who can repurpose used gear is going to save several months of waiting time.
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Old 04-17-21, 10:25 AM
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You can't have it both ways. Unable/willing to do your homework, unwilling to order without knowing what will fit. You have more BBs and cranks on hand then many shops do... Andy
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Old 04-17-21, 11:05 AM
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Different brands of square taper crankset might sit differently on the BB giving you a different chainline. So it's going to be a try it and see with used stuff unless you know and use what the bike came with originally.

I'd throw away any square taper BB I found if I had my way. Just like I'd cut down any Bradford Pear tree or Popcorn tree (Chinese Tallow) and rid the world of them. <grin>
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Old 04-17-21, 01:19 PM
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pstock you are almost there as far as disambly goes. Remove the white plastic bearing seperator slide the balls toghter the axel should move enough to get the balls out. To reassemble grease ,put the balls in, spread them out ,and press the seperator back in. As for the drive side look in the shell if the balls are visible flush out with solivent. go to the farm supplu or auto parts store get a needle atachment for a greese gun slide it under the seal and regrease, reassemble the non drive side.
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Old 04-17-21, 01:40 PM
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Old 04-17-21, 01:42 PM
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Originally Posted by trainman999 View Post
slide the balls toghter the axel should move enough to get the balls out.
clever, that makes good sense now.
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Old 04-17-21, 01:46 PM
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Originally Posted by brooklyn_bike View Post
I did find and watch that video. that BB TY30 is a different construction - it has that nut holding everthing together.
but I cannot quite seem to get my BB shell to slide up and away, revealing the axle.
Now mine might just be stubborn and seized. but even in a vice and giving it a light tap on the top of the axle head, I was not able to get it to move.
SHimano must have got it all together from parts at some point however...
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Old 04-17-21, 02:13 PM
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You might find this post of interest: Repacking a Shimano BB-UN55.

There's a PDF attached to the opening post.
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Old 04-17-21, 07:13 PM
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I thought there was a taper square BB that contained a horizontal adjustment for achieving chainline straightness. If you come across it, it might be an option to work across many of your future builds.
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Old 04-17-21, 09:08 PM
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There were early Shimano BBs where a squarish nut held the spindle in place. You'd need a special socket though.
Newer ones have a press fit ring instead of the nut IIRC, as said above you can't disassemble them with common tools. Maybe an hydraulic press, but you risk damaging the races.
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Old 04-17-21, 09:25 PM
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Originally Posted by Troul View Post
I thought there was a taper square BB that contained a horizontal adjustment for achieving chainline straightness. If you come across it, it might be an option to work across many of your future builds.
Phil Wood makes cartridge bottom brackets that are held in place with lock rings that thread inside the shell, allowing the mechanic to make small adjustments to the chainline. https://phil-wood-co.myshopify.com/c...ottom-brackets

It doesn't perform miracles. You have to select a spindle length that approximates the shell width, chainline, and clearances.
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