Brompton front axle thread?

[LittleWheelsandBig]

Does anybody know the dimensions for Brompton’s standard front axle? Is it 5/16" 26tpi or M8? If M8, is it fine (seems more likely) or standard?

There is some surface rust on the front axle nuts on my Brompton but not on the bling Ti nuts on the rear axle of my B. Swapping the front nuts to Ti (from a non-bike supplier) would solve that problem forever.

[rogerzilla]

Many stem expander bolts are M8 x 1.25, if you have one to try. 

[mzjo]

Many stem expander bolts are M8 x 1.25, if you have one to try.

ISTR M8x1.25 is the bog standard M8 thread. I would guess (but don't have the humongous thread tables on this box to check) that M8 fine would be 1mm pitch (like M7 and M6 standard).
Surely the OP has access to metric and imperial thread gauges and a vernier caliper? Of course you would need as much thread showing as possible, 25.4(mm) is very close to 26 (tpi).

[LittleWheelsandBig]

Calipers, both digital and vernier, but no thread gauges. I have found that thread ODs can be a little undersize than their nominal dimension, due to rounding of the thread peaks.

I am pretty lazy about measuring it since I would have to remove the wheel. I hoped that this information would actually be recorded somewhere as just about every other thread dimension on a Brompton is.

[rogerzilla]

Thread ODs are always undersize...counter-intuitively, an M8 bolt will always drop through an 8mm hole.

[JonBuoy]

It looks like it is 5/16" 26tpi:  https://www.perennialcycle.com/brompton-axle-fastenings-for-front-hub-std.html

[LittleWheelsandBig]

So you found that too.

[JonBuoy]

5/16" is definitely looking promising:  https://josephkuosac.com/product/brompton/hub-nut/

[LittleWheelsandBig]

Bugger. That means I need to get the expensive aftermarket nuts, rather than off-the-shelf metric Ti nuts.