Bottom bracket problem

[Dare]

So guys I need to check with you if you have any suggests for how to deal with this problem I am having with bottom brackets on my Brodie.
Non-drive side of the bottom bracket doesn't screw all the way in. When I remove right side of BB left side goes whole way in so there is no problem with threads. It is 68mm BB 122,5 axel length.

 

[Remko]

Re:

I would say 1. the bb housing is machined (because of? no idea) and made a few mm shorter than the original 68 mm, or 2. your bb is a 73 mm oversized type, or 3. there's some hardened glue residue inside the left cup.
Curious which is option 4.

 

[Trebz]

Re:

Some info on how to chase threads below. You might get away with just extending the internal thread a little bit:

http://www.parktool.com/blog/repair-hel ... -section-3

 

[Dare]

Well I got back from work and without even changing took the tools and tried to examine what is actually going on.
It appears that by shell is 67,8mm wide while bottom bracket shell is 68,6mm wide. It explains the gap. Threads on both sides of BB shell are intact and each side of bottom bracket screws all the way in when I screw them individually.

The most important thing is that this gap is not a problem, as BB sits tightly in it's place and makes no sounds.

 

[old_coyote_pedaller]

Re:

As you say when screwed in on it's own, the left/NDS cup screws all the way in so the threads on cup and BB housing are OK.

Could be as has been suggested it's a 73mm BB in a 68mm BB housing. So you need to measure both the BB housing and the BB you have fitted to see if they match dimension wise. Think it is unlikely that BB housing has been machined narrower but it is a possiblity.

But what strikes me is that the cup has a shoulder like a DS cup has which butts against the BB housing when fitted. Just had a look at a Shimano BB I have handy and NDS side cup has no shoulder but is threaded right to outside end of cup. When I've fitted BBs to several bikes there has often been threads on NDS cup sticking out after DS is fitted first and NDS is fully tightened against BB cartridge in housing. So maybe it is tight against the BB cartridge and all is OK. I concede it doesn't look pretty though.

Edit to say that I read you newest post before posting mine and I see all is OK.

 

[Max P]

What BB unit is it?

Best solution if it is a flanged type (ie designed to butt up against the frame shell rather than internally as OCP above says) is to add a thin BB spacer as required.

 

[ishaw]

Just a thought. Did shimano make square taper bbs for e-type front mechs?

 

[mikee]

Get a spacer made up , you need it sitting flush


Mike

 

[FMJ]

Just a thought. Did shimano make square taper bbs for e-type front mechs?

Yes. I have at least 1 UN71e.

 

[ishaw]

Maybe this could be the cause of the extra space then?? Weren't they slightly longer to allow for the front mech bracket?