Yes I realize that it is left hand thread and it was a 5/8" bolt that I got at Lowes. I had to use a extension bar on the wrench and two of us working it and I actually thought there should be no problem getting it off. Well I got to see the floor rather quickly. OUCH !!

If you broke a 5/8" bolt I salute you. (my brain fart for typing 7/16" above) That takes a lot of force to do that. Hopefully you didn't hurt yourself when it let loose. I use a 24"-long 1/2" breaker bar and a high-quality 15/16" 6-point socket and I figure I'd bust the socket or the 1/2" drive pin on the breaker bar before I ever broke a 7/16" bolt.

I saw a picture of a bolt and washer setup to hold an adjustable wrench in place. So that will be my last option for seeing if I can get this cup off. I suppose I could try to heat it as I try to turn the cup.

Well we both went flying on the floor when this bolt broke. Maybe it was a defective bolt. I was surprised as well that it broke.

Well I finally got the fixed cup off and here is how I did it. Got this picture off the internet and it took some doing but it came off.

What did the wrench flats look like when you finally had it out? Did they get chewed up?

I like to chase/face the shell after pulling apart an old BB. Some of these old bikes are just nasty. Cleaning up the threads and the faces makes them look better than new.

Actually the wrench looked okay. I got the wrench as tight as I could and had had a friend put the nut and bolt together so there was not play and using a 15" wrench sure helped as we had lots of leverage. Then one of us held onto the frame and the other one gave it a quick heave hoe and it came loose right away. Thank god though that I don't have to do this a lot. I used a lot of WD40 to try and help loosen it but I give up on that for situations like this.