[Closed] Seized bottom bracket cup

Do you have a Dremel? If so, its possible to cut slots in it, get it into sections. Must say that I haven't done it with cups on a BB shell, but have done this with headsets, races and cups.

No Dremel or anything that small I'm afraid. I'm wondering if I can drill 2 holes on opposite sides of the cup to slide some kind of rod through but there isn't much thickness there.

Would some M10 30mm O.D. washers catch the bearing seat lip? If so you could put one washer either side, tighten a M10 nut and bolt through the washers then use a large socket on the bolt/nut to screw it off. I.e. a variation of sheldon's method for fixed BB cups https://www.sheldonbrown.com/tooltips/bbcups.html

I think because you are working on the NDS and fixed cups were on the DS you may have to change the directions. You must be tightening the nut/bolt in the same direction that the cup unscrews for it to work. I think that mean you might need a long reach socket or extender to work on the bolt inside the bb shell from the other (DS) side.

Vice and turn the frame?

I presume you mean external cups? If so, I'd try plumbers stillsons first. Secure the bike and really give it some force.

In the unlikely event that it still wont move, I'd cut or grind a slot and hammer/cold chisel/drift it at an angle to get it moving. A combination of shock and brute force in the right direction should do it.

Hacksaw

+1 on 18" Stilsons

Thanks for the replies. I don't think I have any stilsons but have been going at it with a pair of cobras ( https://www.screwfix.com/p/knipex-cobra-water-pump-pliers-10-250mm/9144x ) but although these grip the cup tightly, there is not enough leverage to budge it. I can confirm that boiling water made no difference by the way.

Cut a slot in it, it will collapse and unscrew.

cynic-al, just so I'm sure...

Do you mean cut across the outer face of the cup, like so...

...or putting the blade through the shell and cutting into the inner lip of the cup like this?

For it to collapse, option 1 but I wouldn't do that until a last resort as you may damage the thread.

Try cut a slot as option 1, about 5mm wide and drift it in the right direction.

Sorry, that should say for it to collapse it needs to be cut as option 2 but I would try option 1 and a drift first.

hooli, I just gave that a go. I filed 4 slots around it so I could attack it from different directions with a lump hammer and cold chisels but all I got was acute tinnitus. I'm a bit fearful of cutting it now because I would reach the tips of the threads from the frame before cutting through the threads of the cup surely?

Option 2. Yes you need to get pretty much into the threads. I've done this with a UN72 BB, should be the same principle. You might need to cut the slot all the way to the outer cup so it can compress. I'd cut the slot where either tube welds on to the bb shell so there is more meat around it. You shouldn't damage the treads in a way that would cause a problem in use, even if you cut into them I don't think it's a significsnt stress raiser.

Cheers cynic-al

I decided go at it with a round file, figuring it would cut more slowly but remove more material making a nice channel so I could easily see when the threads starting breaking through, plus weakening a greater area of the cup. Gotta be careful not to hit the threads on the opposite side. Got the outer lips right down to the face of the frame* and cut into the inner cup till I fancied it must be very close to the threads, then squeezed the outer lips inwards in a few places with the cobras, It then unscrewed.

*Actually I went a little too far on the outside and skimmed the frame slightly but the threads seem untouched so I'm chalking this up as a win. Thanks all.

Big dollop of coppaslip for the new one!

Good result in the end