Very quick question about the SRM sprocket nut

[BSA500]

what size is the srm gearbox sprocket nut. See told you it was quick :)

[orabanda]

1"AF

[RoyC]

1"AF

And that was a quick answer,

[BSA500]

Sorry should have been more specific, what size socket/box spanner do I need. My box spanner I have is 1 7/16 AF and wasn't big enough.

[RichardL]

Uuh, I deleted my previous post when I realized you were probably are not talking about the cush nut.

[JulianS]

1 1/2 inch AF.

[BSA500]

Thank you. I did measure across the flats,but wasn't sure if AF means across the flats seems it does :)

[Greybeard]

Thank you. I did measure across the flats,but wasn't sure if AF means across the flats seems it does :)

AF means American Fine but I believe the size refers to the distance across the flats.

[JulianS]

I use a long ring spanner. Sockets not deep enough due to the mainshaft.

[Rex]

AF means American Fine but I believe the size refers to the distance across the flats.

Errr...A/F means "across flats" ..

[BSA500]

those spanners are expensive 

[Greybeard]

AF means American Fine but I believe the size refers to the distance across the flats.

Errr...A/F means "across flats" ..

Well, there I go talking utter ballcocks! I was introduced to the term American Fine when I was young and never had reason to doubt it until now. Thank you. 

[chaterlea25]

Hi All

those spanners are expensive 

Try Army Surplus stores or autojumbles, You can usually buy big sockets for small money
38mm is near enough 1.5in as makes no difference (0.1mm)
I have cut sockets and welded in extension pieces to access gearbox sprocket nuts

John

[duTch]

 maybe keep an eye out for a flogging spanner (one-ended ring spanner made for a hard life) ?

[orabanda]

The spanner, or socket, should not be expensive.
The size of the hex is 1"Across the Flats (AF).

If your tool box includes a 1/2"drive electric or pneumatic rattle gun, all you need is the socket ($25 - $30).

A 1" combination or ring spanner will be $25 - $60, depending on brand; even the cheaper (asian) spanners are OK.

Pic of nut below:

Richard