Updating older bottom brackets
Symmetrical VS non-symmetrical spindles Some BB are non-symmetrical: the spindle is longer on the drive side.
Today it can be hard to find the proper non-symmetrical spindle BB for old cranks.
It's usually possible to fit an ISO crank on a JIS BB.
Every crank's manufacturer recommends a BB type and length.
One solution is to use BB spacers to push the BB over a few mm, effectively making a non-symmetrical BB.
Or you can just get a slightly wider symmetrical BB and not worry about it.
The Italian BB shell is 70mm wide and has 36 mm X 24 tpi threading; both cups tighten to the right.
VO makes Italian threaded BBs in sizes to fit our cranks.