Advice needed: neck truss rod won't move.

4string

Afternoon fellow Boarders. 

Just bought a partscater bass (P body, J neck, 2 band active pre amp) and I am trying to put some front bow in the neck to stop the strings buzzing. With the strings at tension the neck is flat - with slackened stings, there is a back bow.

The truss rod nut is at the neck end and I seem to have got the right sized allen key (imperial measurement). However, I am trying to slacken the nut (leftie - loosie I believe) and it will not budge. I realise the rod is under some tension, so what advice would anyone have to getting the nut to turn? Thanks.

ICBM

Deliberately back-bow the neck by hand - you'll need to clamp one end of it somehow - to take the tension off the nut, and it should be possible to undo it unless it's been cross-threaded. It may require quite a lot of force if it's stuck - don't be afraid of it, if you're undoing.

If it really won't shift it may help to get a little WD-40 down around the nut, but don't overdo it, and make sure you leave it a good time to evaporate off after you've got the nut out - it can soften the wood if you soak it too much.

Sarge

If there is room, try soldering iron in the nut for a wee while, often heat will expand the nut thread and let it move, too much heat and the rod will expand too, which isn't cool.

4string

Thank you both for the advice. @ICBM you have confirmed my thoughts on to move the nut - having tried a little back bow pressure to relieve the nut, I fear it may be a crossed thread, but I am going to try again under more controlled conditions. @Sarge, an interesting additional thought and one I will try before the WD-40 route. Cheers.

4string

And success! Just needed the guitar body clamping down, the neck flex back a little and a longer lever on the allen key :-)

Sarge

4string;1033056" said:

And success! Just needed the guitar body clamping down, the neck flex back a little and a longer lever on the allen key :-)

Excellent, always a bit daunting the first time, I've taken to placing the guitar body facing away from me, put my knee on the back of the neck and gently ease the headstock end towards me, leaves a free hand to tweak the nut.