It's a mid-50s B31 tank with the surface all flush - no recesses. On each side there are two large holes for fixing the knee rubbers, and above and in front of those are two small threaded holes on each side for fixing the tank badges direct to the surface of the tank. These badges are the rectangular BSA with the wing behind the B, about 1" by 2". Does anyone know the correct thread size, form and pitch for the small screws that hold the badges on?
Bill Nelson's been very helpful and if someone has a definitive answer to confirm what he says, that would be great!
Thanks, Mark.
It is either 5 BA (0.126 diameter over the thread x 43 tpi) or 1/8 BSW (0.125 diameter over thread x 40 TPI) . Both will probably screw in given the similarity in size.
Presuming threads not been botched and its not an new made import.
thanks Julian: 1/8 BSW ties in with previous information. Existing threads seem to be OK...