03-02-2022, 04:13 PM
(This post was last modified: 03-02-2022, 04:14 PM by Duncan Grimmond.)
M7 (as with M9 and M11) is something of a "bastard" thread as it is on the cusp of fine to not so fine pitch thread. All three are used quite extensively on 2CV motors and gearboxes as they allow for a smaller boss and reduce weight, very much favoured by M. Boulanger in his 2CV design. He must have saved quite a few grammes like that and somewhat more safely than drilling holes in everything à la Chapman (should that be au Chapman?).