How to fix a Gibson truss rod

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This job used to be so hard that guitar necks got thrown away as "unfixable." Dan Erlewine shows that it's now pretty simple with StewMac Truss Rod Rescue Tools.

Video Transcription

[on-screen text reads: StewMac tools + ideas for guitarmaking. How to Fix a Gibson Truss Rod]

Broken truss rod

Dan Erlewine: This '71 Gibson SG has a broken truss rod. It's really the perfect one to look at because it's very typical. Here's where it snaps off, right where the rod comes out and meets the wall that the acorn nut adjusts against. There's the broken off rod. And I'll tell you one thing right now, when you see a truss rod with that much thread coming through the acorn nut, you know something is wrong. And it's probably about to do what this did, snap right off. This has always been a job that required so much work that people would've thrown the guitar out. You couldn't take off the fingerboard, route out the truss rod, make a truss rod, put it in, put the fingerboard back on and refinish it. That'd be crazy. And if the camera can see this, this half moon metal washer is compressed about a 16th of an inch or more into the wood. It's squashing the mahogany.

Even then when the rod snapped off, it was under so much pressure that it pulled back like a rubber band. It's not even flush up there. So I'm going to dig out that washer. Man, that thing is like it got hammered back in there. You go at this slowly, you got to scrape away the glue or crud. Once you can get it to move a little bit, you can wiggle it out. Here we go.

And it's not always going to be a broken truss rod that these tools are used for. In fact, more often it'll be stripped truss rods or mangled ones that you just need to clean.

Stripped and mangled truss rod threads

Here's a truss rod thread that's been mangled. It's hard to get a nut on it. I can almost get on it, then it wants to stop about that far in. So here's what the Thread Cutting Die can do. It's got a little bit of a bevel on the face so it can get on the end of that rod. And once it starts to bite onto a thread, now it's cleaning them up. You're chasing the threads to make them work again. And I'll thread a bit and back off, thread a bit and back off. You want to clear those chips. Just like that. Or, let's say this is a broken truss rod and you have to add threads to it. I'm going to put a little Vaseline on there to lubricate it a bit.

Adding threads to a broken truss rod

This time we're going to start cutting some new threads. It takes a little elbow grease and you'll have to take the die off and clean it a couple times to get that cut metal out of there. There we go. To remove wood from around the rod, I'm going to use the relief cutter [on-screen text reads: Relief Cutter for Gibson -]. The relief cutter is a boring tool. It's got four sharp teeth that cut wood from around the rod and there's a hole in the center that slides along the rod to guide it, without harming the threads that we know are in there. We can use them if we can get to them. And I'm driving it with a T handled allen wrench. If there's no rod to center on, you might want to hold that down for the first couple of cuts, just to get it started.

That's looking pretty good. I'm going to quit there. What I want to do now is get on those threads and chase them with the 10-32 Thread Cutting Die. It's on already. There, now those are nice clean threads. Now for the fun part, the rescue. We have to put a new acorn nut on it [on-screen text reads: Truss Rod Nuts for Gibson -]. We have two to choose from, the short taper and a long taper. This is the more modern version. That's the older version. I like this one because it has more walls to it and I think you get a better grip. And then there's the washer, that's going to slide over the rod and fill that hole. I'm going to push that on with my truss rod wrench. It's a pretty snug fit. I'm going to have fun right now because it's perfect threads. By the time I tighten this, it'll be just about flush at the end of the acorn nut.

That's about as much as I'm going to give it. I don't want to break it again. Look at that. We're done. Another truss rod rescued. So I just used the rescue tools on a Gibson. That's a 10-32 size. We also have three different sizes for all the Fender guitars, as well.



Dan Erlewine

Guitar Repairman and Builder

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