Everything You Need to Know about Making Truss Rod Adjustments

If you've ever had a guitar with strings that buzzed on certain frets, or had a slight bow in the neck, you may have already done some research into what could cause this.

During your research, you most likely came across the term "truss rod."

The condition of a guitar's truss rod can have a major impact on your guitar's playability and performance. However, if you don't know what you're doing, making truss rod adjustments can actually do more harm than good.

In this article, I'm going to go through everything you need to know about a guitar's truss rod including what it is, signs you need to adjust it, and how exactly to do so.

If you're looking for more general advice, our electric guitar buying guide is a good starting point.

What is a truss rod?

The term "truss rod" is used to define the steel bar that runs along a guitar's neck.

These are present in both electric and acoustic guitars and are used to help prevent excessive bending in your guitar's neck. There are essentially two major factors that cause guitar necks to bend.

1. The pull of your guitar strings (especially heavy gauge strings)
2. Environmental factors that cause wood to warp / bend (e.g. temperature and humidity)

A truss rod combats those two factors by creating counter tension that helps keep the neck straight.

Although the truss rod helps keep the neck straight, it should be noted that for playability reasons, guitar necks typically require a slight upward bow. Therefore, you don't want your guitar neck to be completely straight or else you may experience buzzing and it won't feel right.

Truss rod variations

Now, there are variations to a guitar's truss rod and what you see in one guitar may not be the same in another.

For example, some older models require that you remove the guitar's pickguard or neck in order to access the truss rod.

Other guitars, such as certain Warmoth models, even have a double truss rod as seen in the image below.

Double truss rod guitars have been known to better withstand environmental variables, however some guitarists have also noticed a slight difference in tone as there is less wood in the neck.

In either case, you should know the signs that typically show when it's time to make truss rod adjustments which we'll discuss in the next section.

Signs You Need To Adjust Your Truss Rod

Of course you should not go adjusting your truss rod unless you actually see or hear certain things that give you reason to believe your guitar needs such an adjustment.

A few signs that should tell you whether you need to make truss rod adjustments are the following:

#1: High Action

A guitar's action refers to the amount of space between the fretboard and the strings.

In the photo above you can see a tool that allows you to measure action.

A guitar with high action means that a lot of space exists between the strings and fretboard. Having a guitar with high action can be problematic as it makes pressing down the strings much harder.

This makes it particularly difficult for beginners as basic playing becomes much more strenuous on their fingers.

Moreover, it'll be substantially harder to play any kind of lead lines or melody.

#2: Low Action (excessive buzzing)

On the other end of the spectrum, too much buzzing is a sign that the guitar's action is actually too low.

Since the strings are so close to the fretboard, when plucked or strummed they vibrate and end up touching the fretboard (usually coming into contact with the fret separators), thus creating a buzzing sound.

Both extremes can be addressed via truss rod adjustment.

#3: Poor Intonation

A guitar's intonation refers to how well a guitar stays in tune along the fretboard.

Have you ever played the fifth fret of the B string and it sounded out of tune but when you played the open B string it was in tune?

That's poor intonation.

A basic way to check your guitar's intonation is to play the 12th fret harmonic of a string and then compare it to the fretted note of the same string. If the two notes vary in pitch, this is a sign of poor intonation and could be due to your truss rod.

Locating the Truss Rod

The first step to adjusting your guitar's truss rod is to find it.

The placement of the truss rod's adjustment nut can differ depending on what type of guitar you have and how old the guitar is.

However, in most cases it will be in one of two places depending on whether you are using an electric or acoustic guitar.

Acoustic Guitar Truss Rod Location

On most acoustic guitars, you'll find the truss rod is located just under the soundhole, at the end nearest to the beginning of the neck.

You should be able to see this by simply looking at the guitar at an angle.

The following image shows where the truss rod is located on most acoustic guitars.

Electric Guitar Truss Rod Location

For electric guitars, the truss rod is usually located near the bottom of the headstock, just before the nut.

For most electric guitars it's readily accessible and easy to locate.

The following is an image of where to look for the truss rod of an electric guitar.

While the aforementioned locations are where you can find the vast majority of truss rods for both acoustics and electrics, not all guitar truss rods are as easily accessible.

For example, on certain models of old fender guitars, you actually need to remove the guitar's neck from its body in order to access the truss rod.

On other guitars, the truss rod's adjustment nut is also a little more hidden.

Although located at the same place, certain Gibson electric guitars have a metal plate (shaped like a bell) that is placed over the truss rod's adjustment nut.

Thus, you'll need to remove this plate with a screwdriver before you'll be able to access the truss rod.

Truss Rod Adjustments - How to

Now that you know a little more background pertaining to what a truss rod actually does and where to find it, let's get into how to perform truss rod adjustments.

Some people find it scary to tinker with their guitar's truss rod because they feel they might ruin the guitar.

However, it just takes a little bit of knowledge and forethought to produce the results you want, without having anything go awry.

The first thing you'll need is an Allen key, or truss rod wrench, that fits snug within your guitar's truss rod adjusting nut.

If you bought a new guitar, it may have come with an Allen key already. If not, you can pick one up at any music shop or online. Be sure that the Allen key fits snug into your truss rod so that you don't strip the truss rod's nut when making adjustments.

With your Allen key in hand, you can now start making adjustments to your guitar's truss rod.

The first thing you need to do is determine whether your guitar has an upbow or a backbow.

I'll explain the difference of each and how to correct them both.

Fixing an Upbow

An upbow occurs when there is too much relief, therefore requiring you to tighten your truss rod.

If your guitar's action is too high, this could certainly be a sign of an upbow.

Check out the following image to help visualize what an upbow actually looks like.

As you can see, the guitar's neck is quite far away from the strings around the middle of the neck.

The best way to measure the distance between your fretboard and the strings is to use a capo to press down all strings on the first fret and then press down the last fret of the high E string with your finger. Then, go to the seventh or eighth fret (whichever has more distance) and measure the distance between the fretboard and your high E string.

It depends on your playing style, however a standard measurement between your fretboard and strings at the seventh fret should be approximately 0.007 inches.

Now, once you have identified that you actually have an upbow in your guitar neck, it's time to adjust the truss rod to fix that.

To rectify an upbow, you need to tighten the truss rod. In order to do this, the truss rod's adjustment nut must be turned clockwise.

Follow these steps when making adjustments to fix an upbow.

1. Ensure your guitar is in tune, this is important as it creates the proper tension on your guitar's neck.
2. Start by turning the truss rod adjustment nut by 1/8th of an inch clockwise.
3. Retune your guitar (this is important).
4. Apply the capo to your first fret and press down the high E string on your last fret. Then, measure the distance at the seventh fret.
5. Repeat this process until you have reached the desired distance between your fretboard and strings.

Fixing a Back-Bow

On the other hand, a backbow occurs when there isn't enough relief.

If you notice that your guitar strings are buzzing against your fretboard, this may be an indication of a backbow.

To help visualize what a backbow looks like, check out the following image.

In this case, the fretboard is quite close to the strings, especially in the middle of the fretboard.

For measuring the distance between your fretboard and strings, you'll want to follow the exact same process as above.

Simply apply a capo over the first fret and press down on the last fret of your high E string. Then, measure the distance between the fretboard and your high E string on the seventh fret.

If you can't measure any distance, because your string is touching the fret, then this is a good sign your guitar neck has a backbow.

To fix a backbow is quite similar to fixing an upbow, the only difference being that you must turn the adjustment nut counter-clockwise.

Follow the steps below to fix a backbow.

1. Ensure your guitar is in tune, this is important as it creates proper tension on your guitar's neck.
2. Start by turning the truss rod adjustment nut by 1/8th of an inch counter-clockwise.
3. Retune your guitar (this is important).
4. Apply the capo to your first fret and press down the high E string on your last fret, then measure the distance at the seventh fret.
5. Repeat this process until you have reached the desired distance between your fretboard and strings.

Additional Tips

Once you know a few key concepts of how a guitar's truss rod works, you should be able to make the slight adjustments required to fix any up or backbows in your guitar's neck.

There are however a few additional tips that I wanted to provide for people making truss rod adjustments.

These tips are just as important as what I've gone through above so ensure that you take each point into consideration.

• Use a string action gauge to measure the distance between the fret and the string: When measuring the distance between your fretboard and strings a great tool to use is the String Action Ruler tool (pictured earlier). This tool gives you an easy way to accurately measure your guitar's action.
• Mark the starting position of the truss rod adjustment nut: Before making any adjustments to your truss rod's adjustment nut, be sure to mark the position of the nut with a piece of chalk, or something erasable. This will provide you with a starting point for which you can use to measure how much you've adjusted the rod's positioning.
• Don't keep tightening your truss rod if there is too much tension: Whether you're just starting to turn the adjustment nut or have already made previous rotations, if you ever start to feel that too much tension is building, you should stop making any adjustments. In this case, if you keep tightening or loosening the truss rod, there is a chance that it might break, causing a much larger problem. Instead, take your guitar to a technician at this point. While it may cost a few dollars, it will be much cheaper than fixing a damaged truss rod.
• Stop adjusting your truss rod if there is no impact on the neck's curvature: If you're either loosening or tightening your truss rod and notice that no changes are being made in terms of the guitar's neck curvature, it is advised that you stop making any adjustments. This goes hand-in-hand with the point mentioned above. At this stage, it's best to bring your guitar into a professional guitar technician to have them take a look.

Summary

A truss rod is an extremely important piece of any guitar's anatomy.

It helps counteract the natural bending of wood, therefore allowing you to take your guitar into various environments (hot, cold, humid, etc).

Although truss rods sometimes need to be adjusted, it's important to first determine if the problem you're experiencing with your guitar is in fact due to the truss rod itself.

Once you've confirmed the issue and followed the steps outlined in this article, you should be well on your way to fixing your guitar's truss rod and having a playable and great-sounding guitar again.