Hohner B2 truss rod hex size?

[Leyland Ska]

Trying hex wrenches (good quality ones), 5mm fits in the socket but is loose. 5.5mm and 7/32" don't fit.

Could it be 13/64"?

I can't reach a Vernier caliper into it, or get a decent imprint of it with Blu-Tac

The hex socket looks in good shape, not rounded.

[tauzero]

Mine is a nice snug 4mm. Go smaller.

[Leyland Ska]

Hm. A 5mm hex is loose, sloppy fit in the socket. A 4mm will probably not even touch the sides. I definitely don't need to go smaller.

 

Wondering if Hohner have ever used 13/64" or anything else exotic.

[tauzero]

Have you tried putting a 4mm in there? There's an initial round hollow bit (which a 5mm would go into) followed by the 4mm bit (which a 5mm wouldn't). Everybody in the civilised world uses 4mm. Hohner use 4mm on the B2.

[Leyland Ska]

I will definitely give it a proper go when I get home, thank you for the suggestion. 

[Leyland Ska]

I'm not convinced it was ever a 4mm. As I expected, 4mm first even touch the sides.  The 5mm engages but isn't quite snug and I don't want to put any torque on it really. 

 

But it does look a little abused on really close inspection. Maybe it was a 5mm once. 

 

It's a B2A fretless with full inlays (looks fretted until you're up close), but I don't know its serial. Guess it is "uncivilised". Certainly the neck is like half a baseball bat.

[PaulThePlug]

Do you have any Torx bits?

Maybe one of them might be a snug fit. Will have a look at mine.

 

If the action is near enough etc, 

As a 'try' place a bit of tin foil, thin  thick or folded, and try the 5mm to see how it feels, then try an un-do first, then nip up.

Edited Thursday at 22:02 by PaulThePlug

[tauzero]

Actually, I was wrong. Jon Shuker used a 5mm truss rod on the bass I've just bought. However, all three of the B2 variants I've had have been 4mm truss rods.

 

That truss rod nut looks a bit mullered. This is what mine looks like:

 

 

If you slacken off the strings, you could take the string holder off (just those two screws) and have a look at the end of the truss rod - you should be able to see more. Not sure if you can take the nut off, or extract the truss rod.