AVM hubs - T15 Torx cone headed bolts

Apparently Brazil is mostly metric, but if their market in the US then as you say they might use imperial sizes. Certainly this bolt is a special shape and that might have dictated the size.

I found my thread pitch gauges here goes:

The thread pitch is 0.8mm or 32 TPI.
The major diameter is 4.0mm

M4 is 4.0mm but is 0.7mm or 36 TPI so it is definately not metric

8 UNC is 4.165mm and 32 TPI, that is as close as I can find across metric, BSW, BSF/BA, UNC or UNF, so I am pretty sure it is 8 UNC.

Robin

I have just checked with my Zues book, and to confuse further - 8 ANC, is also very similar. 
O/D - 0.1640
Core - 0.1234
Pitch - 0.0312
Depth - 0.203
T.P.I - 32

But 8 UNC, will be a much more common thread I would guess.

According to a search ANC is just an obsolete designation, they are the same thread, now referred to as UNC.

There are quite a few of these old threads which have been superceded by a new designation, some are directly compatible, but others only have certain sizes which are compatible and other sizes dropped.

I think this is why Metric threads make life so easy, there is only two, coarse and fine, with coarse been the only one you normally see.

Robin

We had a break in the weather this afternoon, or in other words it stopped raining long enough to get the manual hub fitted and some grease applied over the Torx screws, so the job is now complete, ready for action.

Thanks everyone, I know a lot more about manual hubs, drilling out hardened studs and have increased my tool kit a bit (no bad thing in my mind).

Robin