BB Bearing cup cross threading / Drive side

[scooter]

Hi all , I’m trying to remove this bearing cup on the drive side , left handed thread .
It does about one turn then starts to lock up so I’m pretty sure it’s starting to cross thread , you can see by the photos it’s a bit skee wiff .
Any suggestions on how to remove it ? I’ve tried this threaded bar technique to try and keep it square when undoing but no luck ..
Ta

 

[Paul R]

Have you tried getting some penetrating spray worked in it? I did a bike once and the bearing cup outer flange was made pissed so when it was coming out it looked like it was crossthreaded.

or you could cut slots in it and take it out in peices

 

[scooter]

I’ve just sprayed wd40 inside round the cup .
Was thinking about trying to break / shatter it by clamping it in the vice on both of the flats , hardened steel will be hard to cut I reckon ?

 

[ishaw]

I had a similar problem, but opposite. A BB would slip into any other frame I had, but not the one I wanted it to fit. Any other BB I tried on the frame fitted perfectly. It was an odd one, as it would go in ok to start, then bind.

In the end I just got another BB that slipped in fine. The odd thing was the frame threads were fine, as were the BB. No idea why they just weren't compatible with each other (trek frame, un73bb).

In your case, I'd not want to damage the threads, but it sounds like you've done all the right things in trying to remove it square and true.

You may just have to bite the bullet and get it out and see what's what afterwards. If it's a steel frame and alloy cups, the frame should win and be fine, and a new BB all that's required.

 

[hamster]

As it's removal, if it's cross-threaded then there is nothing you can do about it. Remove and inspect the threads afterwards.

 

[Suprachrgd82]

I don’t think it would cross-thread on removal, particularly since it is fully inserted unless it was cross-threaded when it was initially installed.

I suspect it may be galling. Is the frame aluminum or steel?

Note: WD-40 is neither lube nor penetrating oil. The best penetrating oil is a mix of acetone and auto trans fluid.

 

[bikeworkshop]

Sometimes we've had to weld a bar on the cup face if it's steel.
It is very hard to saw through, if it's an actual bearing cup. Cartridge bbs often have alloy (or plastic) collars.

Bb threads can be repaired, so you've just got to force it out.

If its in there wonky then it's either gone in wonky, the threads are very worn/ damaged already or the cup has split along the thread somewhere

 

[novocaine]

threads don't cross on the way out unless you've removed an entire thread. so unless it was wound in cross threaded (yes I've seen that on the fine pitch of a BB, the frame was a right off, aluminium frame, built by someone else with insurance) it won't be crossed it will be gaulled up though, potentially corrosion, potentially a bit of thread.

time to break out the cheater bar and start looking for threadless BB shells. (or get it repaired, but if you are going to do that anyway, take it to them with the cup still in).

 

[eshew]

Rotate out 2 back in one, repeat. If there is debris this is the best way to get it out of the threads without damaging them. Similar to backing out a carbon fouled spark plug. Back and forth with a lot of lube.

 

[shedobits]

Rotate out 2 back in one, repeat. If there is debris this is the best way to get it out of the threads without damaging them.

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