Reusing Shimano BB Cups

[Croydian]

Hello, Sorry to start a new thread but I can't find the one which contained the information about using boiling water to remove the cups from Shimano BB's to reuse them.
My current head-scratcher is trying to replace the old ball bearing and lockring type bottom brackets on our French tandem (crappy decals removed but it was called a miche or micro or something like that) So far I have removed the left side with the lockring and put in the plastic side of the cartridge Shimano BB I have. The two right side cups are still in place as I'm still looking for a 35mm spanner to get them out (and refuse to walk to the LBS to have them take them out!)
The thread I'm thinking of said the cups can be removed and reused, can any contributors reply as I need an old hand at this to let me know if the BB will be French threaded and if indeed this upgrade if possible with salvaged cups. I seem to remember selling on a couple of UN91's on ebay because they were french threaded typically. I would keep the old BB's but I've bought all new cranks that need shorter axles to allow the front mech to shift and allow the timing chain to line up niclely with the idler wheel. (why did I start! Oh yeah the ridiculously cheap cranks or ebay USA)
Apologies to anyone completely bored with such a non retro MTB thread but this is the forum for the most dedicated fettlers I know of and who I'm sure given the opprtunity would like to help me bodge this rig back together over a couple of Stellas given the chance

 

[dyna-ti]

This is an off topic subject

 

[Croydian]

thank you dyna ti

 

[tenbikes]

This is an off topic subject

Maybe, but I'm interested.............

 

[perry]

ill give this a go

am i right in thinking you only want to change the one bottom bracket or both ?

are the bottom brackets cup and cone type ?

the only way of being certain regards the threading would be to remove the right hand cups . but being french id hazard a guess that it would be matching cups both sides . id try loosening anticlockwise first and if needed

what condition is/are the bottom bracket/s in ? and is there replacement only due because of spindle length and the chainline issue ?

if it/they rotated with a smooth action lacking any griity feel or notching id consider just changing the spindle for another . discard the bearings as a matter of course and check the original spindle for signs of pitting or uneven wear . if its in okish condition clean out the cups ( and the one in the right that you wouldnt need to remove ) and run a ball point pen on the bearing surface . if it catches it/they will need replacement . if they are fine id leave the cup in and just get a new correct length spindle .

if you really really really want to change to cartridge type im afraid i have no knowledge of being able to remove the right hand side cup and change it for the other thread wind . and isnt it always the way that you sell something then shorty after its the one thing in the world you need

 

[one-eyed_jim]

Hello, Sorry to start a new thread but I can't find the one which contained the information about using boiling water to remove the cups from Shimano BB's to reuse them.

It's here:

http://www.retrobike.co.uk/forum/viewtopic.php?t=50349

Note that that only works for those that have a separate, pressed-on aluminium drive-side cup, like the UN70, UN90, etc. but NOT most of the later (UN73, UN74, BB6500) or cheaper (UN52, UN53) models, where the drive-side thread was turned into the steel body of the unit.

My current head-scratcher is trying to replace the old ball bearing and lockring type bottom brackets on our French tandem (crappy decals removed but it was called a miche or micro or something like that)

If your tandem's older than the late eighties or so, the odds are good that the bottom bracket has French (35mm x 1mm) threading. The problem you're going to have is finding French cups with the necessary 30mm press fit dimension to use with the Shimano cartridge. TA make them, as do Phil Wood, but both are pricy and hard to get hold of. Spidel and Stronglight have made them in the past. It's unlikely that you'll be able to re-use the cups that are currently in your frame, but you might be lucky.

The thread I'm thinking of said the cups can be removed and reused, can any contributors reply as I need an old hand at this to let me know if the BB will be French threaded and if indeed this upgrade if possible with salvaged cups.

As above, if the tandem's older, the cups are probably French. You need to figure this out in any case to remove the drive side cups. If they're French, they're right-hand threaded, and remove anticlockwise. If they're BSC (or Swiss...) they have a left-hand thread and remove clockwise. Probably the simplest thing (if there's no marking on the cups) is to compare your old and new left-hand cups. Hold them together and see if the threads mesh fully, peak to trough. If they do, they're both BSC. If they don't, one is metric.

I suppose there's a slim chance you have Swiss threads too, but first things first.

I seem to remember selling on a couple of UN91's on ebay because they were french threaded typically.

Italian, more likely. Shimano did make French-threaded cartridge bottom brackets for a while, but they were always quite rare, even in France.

 

[fatfixie]

From memory French threading is right hand thread both sides, and both sides are the same as l/h bsc cups

so it would seem to be as easy as using 2 l/h side cups from a british thread b/b

The cups can be removed from Shimano b/b's by drifting them off- hot water should not be neccessary

no real way to tell if the b/b is french threaded without taking it out.

If you can let me know the length of bb axle required i might be able to suggest some alternatives.

feel free to PM me if i can be of further assistance

Andy

 

[one-eyed_jim]

From memory French threading is right hand thread both sides, and both sides are the same as l/h bsc cups

No, they're metric diameter and pitch, 35mm x 1mm.

so it would seem to be as easy as using 2 l/h side cups from a british thread

That's a recipe for mangled threads. The cups will work loose in the frame because the only thing holding them will be an interference fit between the mismatched threads. Once they start to squirm around, you risk damaging the frame.

The cups can be removed from Shimano b/b's by drifting them off- hot water should not be neccessary

It isn't necessary, but it reduces the force needed. There's adhesive in the interface that's softened by heat. Bottom bracket bearings aren't designed to take axial loads.

no real way to tell if the b/b is french threaded without taking it out.

He's got one side out already.

 

[fatfixie]

see below

 

[fatfixie]

see above