Yamaha Pacifica truss rod size?

nonesuch

Does anyone know what size Allen key I should use to adjust the truss rod of a Yamaha Pacifica 303-12? I think it’s from 1996 if that makes a difference.

I can’t seem to find a definitive answer online, and I haven’t got anything that’s an exact fit.

I’ve just got this guitar second hand, and I’d like to adjust the truss rod a little bit, and check that it’s actually working properly.

SteveRobinson

It will be a metric size - 4mm or 5mm (I think the latter)

nonesuch

Thanks Steve - now at least I know what I'm looking for. I seem to have every other size!

ICBM

If it's a 5mm, don't try to use a 3/16" - it will go in easily, but it's too small (4.76mm) and there's a good chance of damaging the inside of the nut. I think this is one of the reasons manufacturers seem to be moving away from 5mm to 4mm, which there isn't such a 'near fit' Imperial size to. 5/32" is 3.96mm, which is so close to 4mm that they're interchangeable with no risk.

(The opposite way round applies to US 1/8" sockets, eg on the USA Standard Fenders - a 3mm key will almost always damage these and mean the nut has to be replaced.)

nonesuch

I've just bought new set of Allen keys - so I've got loads of sizes - metric and imperial.

The 5mm fits in but it seems a little too small - there's a little bit of movement left and right. So I don't want to damage the nut by trying to use that. And the 5.5mm is definitely too big.

Not sure what to try now. The nut looks alright, it doesn't seem to be damaged.

SteveRobinson

Use the 5mm key, it should be fine.

nonesuch

I tried using the 5mm key, but I couldn't seem to tighten it at all. (I did manage to loosen it a bit.)

Anyway I've just been to see a guy in a local guitar shop, and he put a bit of oil on the truss rod nut, and although still quite stiff it seems to have loosened up enough to adjust.

So thanks to @SteveRobinson and @ICBM for the advice and encouragement!