Originally Posted by
webtwo
Another method to deal with an incorrectly threaded English BB is to install a French BB. French BBs (probably unobtanium today) have a slightly larger diameter. I had an aluminum MTB frame back in the mid-90s that had damaged BB threads. A shop threaded it for a French BB and saved the frame from the scrap heap. But then again, maybe impossible to find a compatible French BB.
Are you sure it was tapped to French dimensions? As I remember, French BB shells have the same thread depth as British BBs.
Standard procedure when I was working in bike shops in the '70's and '80's was to tap damaged British BB threads using Italian taps.
Just checked
the Sheldon Brown page that gives information about taps:
"
Special taps are made for bottom-bracket threads. These can clean up threads which have been lightly damaged, or have become clogged with paint or threadlock compound. Unless a bottom bracket shell with seriously damaged threads is very thin, or already Italian threaded, it can be resurrected by tapping it out to the slightly-larger Italian size. Cartridge bottom brackets with Italian threading are available from Phil Wood, Velo Orange. TA and perhaps other manufacturers. A bottom-bracket tap set includes a special tool to align the taps at each side of the bottom-bracket shell with one another, and a cutter to smooth and align the cup/ lockring face at each end of the shell."
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