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Hello and welcome to the site! In this post, we’ll discuss a common ailment plaguing guitars and their repairers. Today we’ll go over how to deal with a stripped guitar truss rod.
Truss rod problems are one of those issues that can send shivers down the spine of most guitar repairers (myself included). These repairs can range from a minor inconvenience to a major ordeal and pain in the a**!
The idea for this post came from an email sent by one of my readers. He had recently picked up an Epiphone EB-0 bass similar to the one I reviewed in my other post linked Here. Awesome!
But…
That was only after he could not do a setup on his current bass due to a stripped truss rod nut. Bummer!
It got me thinking that this was a common repair I hadn’t covered on the site. So in this post, I’ll be going over truss rod basics, how a truss rod can get damaged, and how to deal with a stripped guitar truss rod!
Disclaimer: I encourage my readers to try their own guitar repairs and maintenance. However, in this post, I’m a little hesitant to do so.
Truss rod repairs can be tricky, and sometimes they turn into major surgery. Often this is a job best left to the professionals. However, read on if you have guitar repair experience, are a brave soul, or you’re just checking this post out for informational purposes. Remember that I, my blog, and my Youtube channel are not responsible for any injuries or damages you may cause to your guitar or yourself.
Also, I’ll be focusing on electric guitars and basses in this post.
Guitar Truss Rod Basics
Before I get into truss rod repairs, we’ll go over some truss rod basics so we know what we’re dealing with. And yes, this section is a little boring but bear with me….
So what is a truss rod??
A truss rod is a long, threaded metal rod (or rods) inside the neck of your guitar under the fretboard. There will be an adjustment nut located at either the headstock or the neck’s heel. This applies not only to guitars but many other stringed instruments as well.
What does a truss rod do?
A truss rod’s job is to help counteract the string tension on your guitar’s neck. Over time the pressure from the strings can pull a guitar’s neck forward into a “front bow,” aka neck relief. A front bowed neck has a concave curve on the fretboard side of the neck.
Now a little bit of neck relief is fine for most setups. But on the other hand, too much relief can result in overly high action and intonation issues. Think about those nice “Ski Slope Necks” you find on some older, neglected guitars!
Tightening or loosening a truss rod allows you to adjust the amount of front bow/neck relief your guitar has. Tightening a truss rod bows the neck back against the pull of the strings, thereby straightening the neck. Vice versa, loosening the truss rod allows the strings to pull the neck forward slightly.
Surprisingly, there are many types of truss rods out there, each with its pros and cons. I won’t bore you and dive into all the types of truss rods in this post. However, there are three basic types that you need to be aware of when doing repair work.
These are “single-action” truss rods, “dual-action” truss rods, and “two-way” truss rods.
Single-action truss rods are the simplest, cheapest, and probably most common type, especially on vintage instruments. They’re “single-action” because they can only move in one direction. A single action rod can only flex a guitar’s neck back against the pull of the strings.
Single-action truss rods are simple and only consist of a single rod, an adjustment nut, and an anchor at one end.
Dual-action truss rods are similar to single-action ones in that they only use one metal rod. However, they can move in two ways. This allows them to correct both a front-bowed and back-bowed neck. Back-bowed necks are rare, but when you run into one, a dual-action truss rod can be a God send!
A two-way truss rod can move in, you guessed it, in two different directions. This type of truss rod can also correct a front-bowed or back-bowed neck. Two-way truss rods use two metal rods/bars connected at either end.
Side Note: The exact definition of dual-action vs. two-way truss rods will vary depending on who you ask. Often they’re used interchangeably. The above descriptions are the ones that I use and believe are correct. Even so, I’ll probably still get some nerdy, basement-dwelling internet troll trying to mansplain me about it…..
How a truss rod mounts into a guitar neck will vary slightly depending on its type. Most two-way truss rods sit in a straight channel that runs the length of the neck. On the other hand, most single-action truss rods sit in a channel that’s curved slightly from front to back.
Also, single-action truss rods anchor in the neck at one end. The rod will have a hook or attach to a metal stud pressed into the neck’s heel.
How a truss rod mounts into a neck will be important later on in the repair section of this post. Stay tuned!
There are many different types of truss rod nuts, the most common being the six-sided socket head adjustment nut. These adjust with basic hex screwdrivers/Allen wrenches.
Other types of adjustment nuts include…
- Slotted nuts adjusted with a flat-blade screwdriver.
- “Spoked” truss rod nuts that are adjusted by inserting a small metal rod into them and using it as a lever.
- And finally, some truss rods use a basic six-sided hex nut. Gibson has used these on many of their guitars over the years.
The type of truss rod nut used affects how you approach any repairs when one of them is damaged or stripped. Most single-action truss rods will have removable nuts, while most two-way truss rods will not.
The type of truss rod nut used and whether it’s removable will be important later on. Also, stay tuned!
How Guitar Truss Rods Get Damaged
Hey, you still there?? Congratulations, you made it through the boring part of this post!!
There are several different types of damage that a truss rod can suffer.
These include…
- A broken truss rod
- A stripped truss rod
- A stripped truss rod nut
Broken truss rods are the most obvious. When a truss rod breaks, it almost always snaps off at either the adjustment nut or the anchor stud. Broken truss rods are usually the result of forcing a stuck adjustment nut or adjusting a truss rod while still under full string tension.
A stripped truss rod is where the threads on the end of the truss rod are stripped or damaged. This makes the adjustment nut harder to turn and can result in a broken truss rod if forced. The most common causes of a stripped truss rod are forcing the adjustment nut and adjusting a truss rod while under string tension.
And finally, we have the stripped truss rod nut. Now, this could mean two different things. A “stripped truss rod nut” could refer to a nut whose threads are damaged, or it can refer to one whose head is stripped/rounded off.
Quick Tip: Sometimes socket heads can seem stripped when they’re just dirty. The head of the nut can get so packed with dirt that the wrench can’t grip it. If in doubt, try cleaning it out with a toothpick.
The threads of an adjustment nut are usually damaged by (you guessed it) forcing an adjustment. Seeing a trend here??
The head of an adjustment nut is usually stripped/rounded off by using a worn tool or one that’s the wrong size.
Always, and I repeat, always use the correct-sized tool when adjusting a truss rod!! In fact, you should always use the correct-sized tool when adjusting any fastener to avoid stripping it.
Any screwdriver, Allen wrench, or socket should be a good, snug fit with the truss rod nut. There should be a minimal amount of slop/play between the two.
This is especially true with socket head nuts and regular hex nuts. Guitar manufacturers use many different truss nuts in both standard and metric sizes.
I think people get confused over what-sized tool their guitar needs. As a result, I believe many repairers use similar-sized metric and standard-sized tools interchangeably.
For example, the sizes of 4mm, 5/32, and 9/64 are pretty close to one another.
Sure they may be close enough to “make it work,” but it will cause problems in the long run.
Removing A Stripped Truss Rod Nut
Ok, so we’ve covered some truss rod basics and some of the ways a truss rod can get damaged in the first place. Now we’ll finally get into the nitty-gritty of how to deal with a stripped truss rod nut.
I’m not giving a step-by-step of how to go about this. That would be impossible because every situation will be a little different. There are many types of truss rods out there, and every manufacturer builds their instruments differently. The best I can do here is to try and point you in the right direction.
Before starting any repair work, always mask off the surrounding areas of the instrument to avoid any scratches or other damage.
Also, please read this section and the one after it before attempting any repairs.
Single-Action Truss Rods
We’ll start with the easy one first!
As stated earlier, most single-action truss rods have removable adjustment nuts.
If the threads of the nut are stripped, you may still be in luck. Even if the threads are stripped or cross-threaded, you can probably still back the nut off the truss rod if you’re careful. After the nut is off, you may be able to run a treading die (available from lutherie supply houses) of the correct size over the remaining threads of the truss rod to clean them up. After that, replace the truss rod nut with a new one, and you’re back in business.
If the head of the adjustment nut is stripped, things get a little trickier.
On the one hand, if you trash the old nut while removing it, no big deal. You’re going to be replacing it anyway. But on the other hand, any failed attempt to remove the old nut will probably damage it further and make it even harder to remove. It’s a vicious cycle, Lol!
There are various extractors available for both stripped hex nuts and socket heads. Most of these extractors dig into the old screw to grip it.
Stewmac offers a good extractor for socket heads that aren’t terribly stripped. These look like regular hex drivers but taper slightly. This allows the tool to grip what’s left of the head without further damaging it.
Please Note: I am not affiliated with Stewmac, at least at the time of writing. Also, I have not used these extractors myself, but I’ve heard nothing but good things about them.
If an extractor doesn’t work, it’s probably time to call the professionals. Sure there is plenty of improvised “hold my beer” approaches you could try, but I don’t recommend them.
Dual Action Truss Rods
As stated above, dual-action truss rods feature a single truss rod but can move a guitar neck both forward and back. Hence the name dual-action.
The most well-known example of a dual-action truss rod is the Fender “Bi-Flex.” As such, we’ll use this for our repair example.
Fender developed the Bi-Flex truss rod in the 1980s, and it has been used in various Fender models ever since. This design features a single truss rod with an anchor point at either end and an anchor stud in the middle.
This truss rod is pretty easy to spot if you look at the truss rod access hole in the headstock. Guitars with a Bi-flex truss rod will have a round wooden plug (usually walnut) around the truss rod access hole.
This wooden plug is one of the truss rod’s anchor points. As the truss rod turns counterclockwise, it bears on the inside of this wooden plug. This flexes the neck forward to correct any back bows.
The wooden plug allows the truss rod to function as it does, but it also makes repairs much more difficult.
First off, with the wooden plug in place, the adjustment nut will sit deeper in the neck and be harder to get at.
Second, the plug traps the truss rod nut inside the neck, making it impossible to remove without performing some surgery.
So what do we do here??
Well, first, I would try one of the tapered truss rod extractors from Stewmac mentioned above (if the nut is a socket head, that is). You may luck out and be able to perform all future truss rod adjustments with one of these instead of a regular Allen wrench.
If the truss rod nut is badly damaged, you’ll have no choice but to remove the wooden plug to free the truss rod nut. How you go about this is going to vary depending on what tools and experience you have. I’ve heard of repairers drilling, filing, or even steaming the plug to remove it.
No matter how you go about it, this is a tricky repair that’s easy to screw up. In this case, I recommend you take the guitar to a competent guitar repair shop and let them handle it. You should only attempt this repair yourself if you’re experienced or if the guitar’s a piece of crap and you’re not worried about potentially ruining it.
Two-Way Truss Rods
Two-way truss rods are similar to dual-action ones but use two rods inside the neck instead of one. Also, the nut on a two-way truss rod is welded/hard soldered to one of the rods and is not removable.
As with dual-action truss rods, I recommend trying one of the Stewmac tapered hex extractors first.
If the truss rod nut isn’t a socket head or is too damaged for a tapered extractor, then your only option is to replace the whole truss rod.
There are three different ways that you could go about this.
1. The first and most obvious is to remove the fingerboard to get at the truss rod. This will be major surgery for your guitar and is a job for professionals. Also, this repair will be pricey, and not many guitars justify the expense.
2. The second method applies to guitars with a one-piece neck and a “skunk stripe.” With these necks, it’s possible to remove the skunk stripe to access the truss rod. This is also major surgery and best left to the professionals.
3. The third option is the easiest and least invasive. Most two-way truss rods sit in a straight-sided channel in the neck. Also, they don’t anchor at either end. Sometimes it’s possible to pull the old truss rod straight out of the neck and slide a new one in. How you grip the truss rod will vary depending on the nut type and how badly damaged it is.
The truss rod has to have no tension and be in a “neutral” position for this to work. Also, the truss rod channel must be free of any excess glue from when the fingerboard was glued on.
This method isn’t going to work all the time, but you might get lucky with it. If you attempt it, be careful not to scratch or gouge any other guitar parts in the process.
Know When To Ask For Help
As I said in the intro, I often encourage my readers to attempt their own guitar repairs. But in this case, not so much.
If you feel brave and want to attempt some of the abovementioned repairs, go for it! It’s your guitar, after all! Just remember that these repairs can be tricky and are not for the inexperienced.
Also, there’s no shame in asking for help. Know when to admit defeat and call a professional.
That’s All, Folks
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Stay safe, and thanks for reading! I’ll see you at the next one!!
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