One repair method which I had done on an old steel frame was to cut a slot through through BB shell from side to side, on the bottom side creating a slot along the full width. Mechanically close the gap with strong clamps and weld the slot closed and re-tap the threads. Dress off the excess weld and re-paint. It's a skilled job so find a good workshop - but it works.
One repair method which I had done on an old steel frame was to cut a slot through through BB shell from side to side, on the bottom side creating a slot along the full width. Mechanically close the gap with strong clamps and weld the slot closed and re-tap the threads. Dress off the excess weld and re-paint. It's a skilled job so find a good workshop - but it works.