As a follow-up to this question:

What tool will I need to adjust the truss rod on a bass guitar? The guitar in question is a Peavey T-40 with too much relief on the neck.

While I've found a reference to a 5/16" socket bit being able to do the job, as you can see below, the truss cavity doesn't have a lot of room around the bolt to admit a tool. The headstock itself also gets in the way of a socket handle.

enter image description here (Click on the photo for a larger version.)

Do I need to bite the bullet and locate Peavey Torsion Rod Wrench #75031001 (the tool the manual says is needed) or is there another tool I can use for this job? (If it's relevant, this is a long-scale instrument and the headstock is quite large.)

  • 1
    It's hard to tell from this angle, but you MAY be able to use a good pair of needle nose pliers. (Not the real pointy kind). I've had good luck in situations like this with the pliers on my SOG multi-tool. Keep a close eye to make sure you're turning the amount you want, though! If not, a ¼ drive Craftsman 5/16 socket might just barely make it, (looking at the set I've got) but you'd probably have to use a universal joint in order to use the ratchet. Jan 1, 2012 at 2:06

2 Answers 2


The torsion rod wrench is just a very thin walled socket tool so it can fit in that space. You might be able to find something like that at a hardware shop, but you're probably just as well off buying the Peavey tool.


What you're looking for is something like this:

enter image description here

It is simply a socket of the appropriate size with a lever arm on it, designed to fit into a tight space like this. They're common if not universal in the stringed instrument world; Allen hex keys are most popular; most newer Peaveys actually use a wheel contraption that you can just stick any stiff pick or probe-like tool into and turn, no specialist equipment needed. These hex nuts were the thing to use before the Allen driver became popular, and many major manufacturers never switched over, so pretty much any musical retailer should be able to order you one of the right size without having to pay Peavey's markup.

The trick will be determining the proper size. If you happen to have a micrometer you can take your own measurement. Failing that, you might get friendly with a local M&P repair shop; they will have, and need, these wrenches in every size ever made, and can figure out which one you need by trial and error. If they won't sell you (or just let you keep) the one they found that worked, you at least know what size to special-order.

In my experience, which is limited, Peavey has some pretty good customer service. If you called and asked nicely, I wouldn't doubt they'd send you a small part like this just for the PR value. I have a Peavey bass amp from the 90s that was missing a knob when I got it, and they just sent me one in a padded envelope, covered shipping and everything.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.