Metric Hub Bolts
Actually, I just measured some stainless 'M8 A4-80' allen bolts with plain shanks on which I got a while ago for my Ducati. They are just the right length for hub-bolts with the overall length cut down a bit. The shanks are consistently 0.311 - 0.312 diameter which is a perfect fit for hub-bolts, I'm sure Len would agree.
(The collection of standard/original 5/16 BSF hub-bolts I have collected over the years have shanks varying from 0.302 to 0.313 inches - deplorable!!). The M8 heads need a flat to be milled or filed on; so locking as std is guaranteed.
Just as good, the stainless M8 Nylocs I have for them have a nice black nylon insert (not the gaudy blue inserts which are the mark of cheap imported nuts). The 13mm across flats is only about 10 thou down from that of the nominal 0.525 of 5/16 BSF Nyloc nuts; so no-one would know.
For those who remain totally allergic to metric threads, you can buy longer M8 allen bolts with a plain shank at least 1-1/8 long, cut to length, thread 'em 5/16 BSF on a lathe and file the flat on the head.
Either way, the cost-saving is huge and the all important fit is probably better. Use A2-80 or A4-80 in preference to A2-70; they're a little stronger.
I promise I'll get out more.....
Peter Barker
Bristol, UK