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How much force can it possibly need?
#1
Hi folks.
I'm Dave, I'm 19 with no real experience of bike repairs and the like and I'm planning to cycle round Europe for a week with 2 mates. Just tried to replace the BB with varying degree's of success

The old bottom bracket was the kind shown in this article:

http://homepage.ntlworld.com/catfoodrob/choppers/mechanic/bbracket.html

and I removed it as described to replaces it with a UN54 shimano BB. When screwing the new BB in I followed Alex's advice, plastic lockring in a little, cartridge in all the way then tighten lockring. This is where I ran into problems.

when screwing in the new bottom bracket I found it got VERY tight very quickly. Far to tight to screw in by hand, it almost felt cross threaded but after several goes at is I decided that it wasn't cross threaded, just very stiff. I kept screwing it in using more and more force with my large. footlong spanner. I'm not a very big guy but I'm pretty certain I was pushing far more than the 360inch-pounds recommended. So I stopped screwing it in and tried screw in the plastic lock-ring. As it got tighter ad tighter the threads started to snap! so I stopped, cleared the snapped plastic out. removed the cartridge, screwed the plastic lock ring ALL the way in and then screwed the cartridge in until it became painful to put more pressure on the spanner.

The is perhaps 1-2mm of thread between the frame and the edge of the bottom bracket now. so it is not all the way in by any means however it seems tight.

LBS said "ooohhhh you'll need to tighten that" etc.. etc..

ideas please? why is it so hard to thread. is it the rust that was in there before. Does it need to be all the way in? exactly how hard should I be trying when tightening it?

TIA
Dave
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#2
Ask your LBS if they have a thread chaser for your BB.
It could be rust. (unless it's an aluminum frame!) You'll have to re-remove the BB.
2mm will be O.K. but obviously not ideal.
What bike have you got?
[font=Trebuchet MS]Ride hard or ride home alone![/font]
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#3
the bike is a Raleigh Pioneer, fairly old, hence the replacement of parts and the rusting. A thread chaser? I assume that's a tool for cleaning the threads right? Might give the inside a go with a brillo pad first, see if that helps.
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#4
How old? So old that it has a Raleigh-threaded BB? Look at http://www.sheldonbrown.com/bbsize.html table almost at end of page. Described problems fit your description.
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#5
Yep! would concur with Joe_W.
Raleigh did their own thing with various parts of their bikes.
That's why I asked about make of bike.
Other older BB's, French and Italian can also give rise to problems.

New Raleigh bikes though will be O.K.
[font=Trebuchet MS]Ride hard or ride home alone![/font]
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#6
New BBs in French and Italian BB shells seem to work at first except for the right? cup (wrong thread direction) (I know from experience) till they come loose after a while, leaving you with a 40 km march home Wink (didn't happen to me, spotted the problem early enough)
@cyclerUK: I am always astounded how good your "smell" for those things is. Without the question "what bike do you have" I'd not have know where to look... I still have much to learn.
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#7
(04-14-2010, 04:42 PM)Joe_W Wrote:  New BBs in French and Italian BB shells seem to work at first except for the right? cup (wrong thread direction) (I know from experience) till they come loose after a while, leaving you with a 40 km march home Wink (didn't happen to me, spotted the problem early enough)
@cyclerUK: I am always astounded how good your "smell" for those things is. Without the question "what bike do you have" I'd not have know where to look... I still have much to learn.

Hi Joe,
Lots of reading and a good many (too many) years of making mistakes. !!

You obviously have read Sheldon's page on BB threads.

I have been in engineering a long time and have always tried to maintain my cycles, motorbikes and cars myself. Even so there is always something to learn with new technology coming along.

I didn't really expect the "Raleigh" answer but the thought was if the old one came out easy then a new one shouldn't be a problem.

To check the new BB just put the threads against the old BB thread and they should match.
[font=Trebuchet MS]Ride hard or ride home alone![/font]
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#8
Yeah, I read it after I realised that my bottom bracket cannot be ISO threaded (right hand cup was really "wrong"). So I guess I'm on the right way Wink We could have guessed "Raleigh" from the link posted in the first post, though.

There are BBs without threads that can be used to replace obsolete stuff or BBs where the shell threads were damaged (likely to be the case here after two failed installation attempts).
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#9
okay, thanks for the help it does sound like as described in the sheldon brown article. question now becomes: what is the solution? (that doesn't cost more than £15)
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#10
I would see about asking your LBS to chase out the thread.
Diameter wise no problem.
Thread "pitch" wise is 2 threads per inch.
Raleigh = 26 TPI (threads per inch)
UN5? = 24 TPI
Sheldon says it will bind after a few threads but you seem to have proven beyond that.
The very worst is the threads will be damaged and you will have to revert a special BB.
Another option would be to fit news balls and re-instate the original axle.
[font=Trebuchet MS]Ride hard or ride home alone![/font]
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#11
okay think I've found a solution. LBS says he can re-tap the thread to 24 T.P.I, not sure if that will work with the old thread but then also. Stainless Steel resin could be put over the old thread and the new thread re-tapped out of that. But methods cost considerably less than a new frame!
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