Fender-style truss rods that adjust at the body-end of the neck can be a bit of a pain. Sometimes (not often enough), manufacturers build in some concessions to those setting up instruments but even some of these can bring their own challenges.
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Removing a neck to adjust the truss rod is a bit of a pain.
Some Telecasters, however have a channel cut between the neck pocket and the front pickup cavity. Because the neck pickup is often mounted direct to the body, removing the pickguard on those Teles is easy. And, if you're lucky, you'll have a little notched channel to get at the truss rod.
In the very old days*, guitars had no truss rods at all. This wasn’t so much of a problem with gut strings but, once steel strings came along, builders realised that some sort of strengthening was required and so various things began to be inserted into guitar necks to help make them stronger.
A while back, I realised I had a couple of Martin guitars of different vintages in for neck resets. So, with the necks off, I took a photo showing the steel rods they've used over the years.
If you’ve read Sketchy Setups, you’ll probably have spotted that I mention the importance of using the right sized wrench for adjusting your truss rod.
Well, let me just mention it again:
IT’S REALLY IMPORTANT TO USE THE RIGHT SIZED WRENCH!!!
Seriously. Really important.
This is especially true of guitars and basses that use an hex/allen wrench.
Whenever I talk about adjusting Fender guitar truss rods, I try to emphasise the importance of the correct size allen wrench.
Now, this applies to any truss rod that uses a hex-socket for adjustment but especially—really super especially to those guitars with the Fender Bi-Flex truss rod. You know the one—it’s adjustment nut is hidden away beneath a wooden (walnut) dowel and you access it via a narrow hole at the headstock.
Fender use a ⅛” allen wrench to adjust these. Problem is, that’s a relatively small wrench and the ‘flat’ surfaces of the wrench and socket aren’t huge. It’s annoyingly easy to ‘wear’ these flat surfaces so that a wrench no longer grips it.
Allen wrenches that don't fit snuggly, or are themselves a little worn, can wear down your hex edges and leave you with a ruined truss rod nut.
Worn Fender Truss Rod Nuts
You can see what happens in the illustration above. Let’s face it, a circular socket isn’t the most useful thing when it comes to turning a nut.
When this happens, you end up with a truss rod that can’t be adjusted. That’s less than ideal when you’re trying to properly set up an instrument.
Removing Bi-Flex Truss Rod Nuts
It’s possible to remove that walnut plug and to replace the nut. It’s not super difficult but you do need to be careful because, hot!
Yep, we use heat to soften the glue holding the plug in place. Then we can remove it.
Steps For Fender Truss Rod Nut Replacement
First off, strip the headstock hardware. Remove the tuners and string trees. Do this so you can get easy access to the plug. Otherwise, you’re trying to work at an angle and that’s a recipe for burning stuff. Next up, use a sharp knife (Exacto-type) to score the finish around the plug.
Protect the face of the headstock. I just wrap some foil around it a couple of times.
I use a soldering iron. The bit fits into the hole in the walnut plug. Be careful if you’re doing this. I find that it’s not necessary to make contact—the soldering iron doesn’t need to touch the wood.
This is tricky so be careful. The heat from the iron will penetrate through the walnut and soften the glue. It should be ok if the iron taps off the walls of the hole occasionally, but don’t let it remain in contact or the wood will scorch.
It doesn’t usually take too long for the glue to soften. Insert an allen wrench and ‘loosen’ the nut. Turn it counter-clockwise and the nut will eventually butt against the inside of the plug. If the glue’s soft enough, the nut will push it out*.
*A quick note on this: This is very good reason to remove a nut that’s worn before it goes too far. Stew Mac’s Gripper wrenches (see below) can help but sometimes you end up with a completely worn nut and you have to get the plug out by more invasive means.
When the plug protrudes enough, you can grab it with a needle-nosed pliers and pull it out. Be careful—it’s easy to crush or break the plug at this point.
Behind the plug is a washer (keep it).
Behind that is the nut. Fish it out.
New truss rod nut time. On the American Standard, the nuts have a ⅛” hex socket and a 10/32 thread. Lubricate the threads of the new nut with a little (I mean a little) Vaseline and screw it back in. Don’t forget the washer next and follow up by reinserting the plug with a smear of glue.
Depending on the guitar, I’ll sometimes do some finish touch-up.
Help Prevent Worn Truss Rods
- The fact that the adjustment nut is buried an inch deep means that it can be awkward to reach. Sometimes the short leg of your allen wrench won’t reach and you have to use the ‘ball’ end. This makes it harder to get good, deep purchase into the hex socket (and to get decent leverage to actually turn it). Check your guitar stores for a special allen wrench, made with a longer leg, especially for this job.
- Stew Mac offers a ‘Gripper’ wrench. This has a hex head that tapers—it gets wider along its length. The idea is that, as it’s inserted, the wider part might be enough to grip the socket.
This is pretty handy but, if your adjustment nut has started to wear enough that a standard wrench won’t grip, I’d really recommend replacing it. Use the Gripper wrench to remove the nut and install a new one. Otherwise, you risk wearing the nut to the point where even the Gripper won’t work.
- It should be obvious, but don’t force a truss rod. If it’s not adjusting easily, stop and regroup. Try slackening off the strings. If that doesn’t work, you could try forcing the neck into a slight back-bow—using clamps and a brace (second part of this article)—and just tightening the rod to hold it (the rod’s not doing the work to get there). The Rickenbacker Truss Rod Trick can also help.
Let me just repeat, don’t force anything. Check with your trusted repair person if you have any doubts. Remember, this can happen to any truss rod nut—not just ⅛” nuts, not just Fender, and not just hex/allen nuts. I've had to cut rounded Gibson nuts off because people didn't use the right tools too. Be careful.
Just a quickie.
Sometimes, you’ll try to adjust a truss rod and it’ll feel… ‘wrong’. Maybe it’ll be a little hard to adjust or it might just feel ‘gritty’ or reluctant to turn.
Trust your instincts on this. Don’t force it.
Here’s an easy little trick that will often help.
Before you tighten it, loosen it. This on its own can sometimes be enough to free things up a little.
However, even better, is if you remove the adjustment nut completely. Then, clean the threads in the rod and nut as best you can. A small wire brush is helpful but be careful of the headstock finish.
The pièce de résistance… Lube it up.
A little grease or Vaseline works wonders. Don’t go crazy with it but work a little into the threaded hole in the nut and even leave a thin film on the nut’s ’face’ (where it bears against the neck).
Screw it back on and you’ll probably find things much easier to adjust.
When I wrote Truss Rods Made Easy, I mentioned that Ovation, bowl-back guitars, without a regular sound hole, had to have their truss rods adjusted through an access port around the back. I didn't have a guitar handy for a photo, though, and pretty much forgot about it until a couple of weeks ago when I was working on one.
I took a quick video.
And, since I'm essentially an excitable child, I felt the journey inside was just crying out for a horror-movie drone over it.
No, you're a nerd!
This Music Man fretless has a nasty rattle. It rears its head on a number of notes/positions around the board. This particular rattle isn't to do with the string buzzing off the frets (or the board in this case). Here, the rattle is caused by the truss rod itself vibrating.
Inside the neck, there's a channel routed in the wood. The truss rod sits in that channel and, usually all is well. Sometimes, though, there's a small gap—a little play in the tolerances that allows the rod a space to move. That can occasionally lead to a rattling truss rod.
In some cases, simply 'snugging' the truss rod a little more tight is enough to sort things out. Not always, though.
Now, it's worth mentioning that this can be a very tricky problem to resolve. How to proceed is sometimes not clear and, what's discussed here isn't necessarily the solution to all buzzing truss rods. Experience can give you a head-start in making the right call so, if you're in any doubt, seek out some trusted advice.
'Solution'. Get it? I make a glue solution. Get it? Oh, never mind.
In this case, what I'm trying to do is to fill some of the gaps around the truss rod with something other than air. I've watered down some Titebond glue. Watering it down not only makes it flow more easily (there'd be no chance of getting it where I want it at its usual viscosity), but dilutes its strength too—we definitely don't want a glued truss rod.
The diluted glue will, hopefully, flow down the channel and fill some of those spaces. When it cures, it won't be strong enough to actually 'glue' the rod to the neck but will remain in place (albeit probably in a crushed form once the rod is tightened) and continue to fill the gaps.
If this was a fretted instrument, there's a good chance I'd have worked from the fingerboard side—maybe removing a fret or a position marker to drill a hole for access. This would be neater and would let me get closer to the centre of the channel (where I want to be).
Here, though, I've got an unadorned, fretless, fingerboard. Gotta go around the back.
I drilled an access hole at the heel, carefully, until I hit the rod. As an aside, I've spotted that there's already a hole closer to the end of the neck. I chose to ignore it because it meant even farther for my glue to flow and because it was a bit close to the adjustment, 'business end' (no sense risking gumming anything up).
The diluted glue is, slowly, so very slowly, dribbled in. I'm not planning on filling up the entire channel here, I just want to make sure to get a reasonable amount of glue around the rod (primarily at the middle section). I'm obviously holding the neck vertically to allow gravity lend a hand and I've slackened off the rod into a neutral position before starting.
When I think I've got enough, I stop. Then I lay the neck flat on its back. The hope (and when you're working blind like this, there's a good portion of hope involved) is that the glue will pool and cure as planned.
Since the glue in the channel isn't exposed to a lot of air, I play it safe and leave it a few days before working on this again. I want to make sure all of that glue has cured. A rap on the neck seems promising so I reassemble the bass and have a go.
Success. Plug that hole and we're done.
I'm off for a celebratory cuppa. ;-)
NOTE: It's worth stating that, this particular solution can be tricky. You don't want to glue the truss rod into place and you don't want to just inject 'mostly-water'. The consistency of the diluted glue is important. You need a Goldilocks zone—not too thick or too thin. Likewise, if it's not successful first time, earlier glue might block the way for a second attempt. If you're not sure, take the repair to someone who is.