Ha! I kept my mouth shut as everyone was giving their opinions on how to fix the crack, though my opinion was that it probably wasn't a crack. But I thought for me to say so without seeing the bike was presumptuous, and would possibly taken as an insult to your diagnostic ability... But my reason for thinking this, is that it is EXTREMELY unlikely for a shell to crack all the way across as you describe, but very common for them to have a cosmetic defect that goes all the way across - and which could be taken for a crack.
Now I feel better saying so, since Steve Rex thinks so, and I know him to be very smart, experienced, capable and honest. And a nice guy too, for what it's worth.
You tell us it is a BCA shell - any chance it is actually marked BCM? (Bocama?) Either way, it is probably formed out of sheet metal and welded. The vast majority of lugged BB shells were made this way in the period when your frame was made - cast shells were relatively rare. So what you're looking at is probably not a casting mark, but the weld. The weld is ground down to minimize its visibility, and of course tapped inside, but it is usually detectable both inside and out if you know what to look for. And sometimes it is downright obvious where it was welded, and it could definitely look like a crack.
If you would like to post some photos, you could get some more opinions, but none of us will be able to see as much as Mr. Rex was able to see in person.
Mark Bulgier Seattle WA USA
Jack Romans wrote:
> Thanks to all who responded to my post last week re cracked
> BB shell on Vent Noir. Almost all respondants recommended
> either TIG-welding or brazing a reinforcement over crack. I
> took the frame to our highly-regarded local builder (Steve
> Rex) and he said the shell isn't cracked and wouldn't want to
> do the job anyway. My thoughts, could it be a cosmetic
> defect? If cosmetic, would the threads on one side of the
> crack be about 0.001" higher than other side? It looks like
> a crack to me but whom am I to disagree with a pro. Also,
> upon close inspection, the "crack" on the inside does not
> line-up with hairline "crack(s)" on the ouside. Maybe I am
> just seeing surface cracks or imperfections.
> Could the shell be laminated?...there is what appears to be a
> casting seam on inside and out. The lugset is BCA.