1976 Claud Butler Cresta Bottom Bracket issue

[misterjan]

Hi, I seem to be having a problem with replacing the old style adjustable bottom bracket. The right hand cup on the new cartridge bottom bracket I have (UN54 Englsih Thread) won't screw on though the left hand side does. The old cup goes on and off fine, so I am wondering whether its something to do with the TPI and could they be different on each side, maybe the right side re-tapped at some point. Anyway, it's annoying as the old style one is ready for the bin and it leaves me with no cranks on a lovely bike!! Any ideas?

Thanks

Jan

 

[tyred]

Using a small wire brush and some sort of degreaser, clean the threads on the bike and examine them for damage, especially at the very outside. Also check your new BB for damage on the threads. Just because something is new doesn't mean it hasn't picked up damage somewhere.

Compare the threads on the old and the new very carefully to see if they are the same but I would doubt if anyone would re-thread just one side of a bike to take a non standard part. These BB cups are a matched pair.

A well equipped bike shop should be able to run a tap through the BB shell to clean up the threads if necessary.

 

[swee'pea99]

I agree - retapping seems very unlikely. That's an odd one misterjan. tyred's suggestions seem spot on to me - compare the two visually (confirm among other things that the thread goes the same way on both...I know it sounds daft, but who knows), check the new one for any damage, last resort visit your LBS. I know it's a bit embarrassing - you didn't buy the BB from them - but most can take it on the chin, with a view to possible future trade.

 

[hubgearfreak]

you'll no doubt be aware that one side is a LH thread?
silly suggestion i know, but we all need help like that sometimes