Info from a well known website............... Went Swiss in the mid 70's.
That's the French for you
French bicycles before 1980 often used French-threaded bottom brackets (now difficult to find replacement parts for). French bottom brackets, like Italian ones, used right-hand threading on the fixed cups, making them subject to loosening by precession. Motobécane broke ranks with most other French manufacturers in the mid-70s, using Swiss-threaded bottom brackets (also difficult to find replacement parts for now). Swiss bottom brackets were identical to French, save that the fixed cups were reverse-threaded (like English ones), making them immune to loosening by precession. For more information, see bottom bracket specifications.