Making a guitar neck adjustment is really the second step in a guitar setup. The first step is changing the strings on your guitar. Once you have a fresh set of strings on your guitar, you are ready to make a guitar truss rod adjustment if necessary.
Be sure and check my other video guitar lessons on changing electric guitar strings and changing acoustic guitar strings to prepare you for this lesson. After your have made a guitar neck adjustment, you can do a guitar intonation setup if you have an electric guitar.
(Video Guitar Lesson)
Guitar Truss Rod Adjustment
Steel string guitars have a metal rod that goes through the neck called a truss rod. This allows for making adjustments to the neck of the guitar. Nylon string or Classical guitars don’t have the ability to adjust the neck.
When making a truss rod adjustment to your guitar you are changing the curve of the neck. In general you want to have your guitar neck as straight as possible without having any fret buzz.
Reasons for Making a Guitar Neck Adjustment
Here are a couple of common reasons why you might want to make a guitar truss rod adjustment.
- The action of your strings above the fretboard is too high
- You are getting fret buzz on some notes
Evaluating the Guitar Neck
There are a couple of ways to evaluate the neck of your guitar and see if any adjustments need to be made. The first is what is called sighting down the neck. This just gives you a general idea of the current curve of your neck.
The next way to evaluate curve of the neck of your guitar is a little more exact. Press down the 1st fret of the 6th string with your left hand index finger, press down at the 13th fret with a right hand finger.
Then you want to evaluate how high the 6th string is above about the 5th fret of the guitar. You can use your left hand pinky to press the string down against the fret to get a better idea of the clearance. There needs to be some clearance at the 5th fret. If the string is touching the fret, then you will have fret buzz when playing.
If there is clearance above the 5th fret, then your neck does have some relief, or curve to it. How much curve, and how high the string is above the 5th fret is a lot a matter of personal taste and playing style. The gauge of the strings used is another factor. Thicker strings need more room to vibrate than thinner ones.
I personally play my electric guitars with very low action, and I’m a light player. Other people like higher action, and might hit the strings harder in general than I do. So they need a higher action on their guitar.
Some guitars are easier to set up with low action than others. Part of that has to do with the guitar neck radius. The curve of the fretboard. The flatter the fretboard, the lower action you can have.
So basically I’m saying that I can’t tell you exactly how much clearance there should be at that 5th fret, just there should be some. And from there it’s up to your personal taste.
Adjusting the Neck of Your Guitar
Warped Guitar Neck Adjustment
So if there is too much clearance, your guitar neck may be warped. When sighting down the neck you might have seen something like this. OK, if it was this bad your neck is firewood, but you get the idea. And yes I know, the guitar string defy physics 🙂
After you have evaluated the neck of your guitar and determined the neck is warped a little…it’s curved too much. The action of your guitar is too high. This is the case a lot of the time when adjustments are needed.
So first you need to find where on your guitar to access the truss rod.
Many times for an electric guitar truss rod adjustment you will access the truss rod down near the tuning pegs right at the end of the fretboard. Sometimes there is a cover that you will need to remove with a screw driver.
For some electric guitar you have to access the truss rod at the other end of the neck by either removing a faceplate, or actually removing the neck of the guitar. If you have one of these, sorry about your luck 🙁 I HATE guitars that are designed that way. Take it to a guitar luthier and have them adjust your neck.
To me if you can’t easily make small adjustments to the neck of a guitar, that is a deal breaker. And yes…I’m talking to you John Mayer Strat.
For an acoustic guitar truss rod adjustment you will often access the truss rod right inside the sound whole at the end of the neck.
It really depends on the guitar what type of tool you will need to adjust the neck of your guitar. But more often than not it’s a hex wrench. If you bought your guitar new, then it should have come with the exact tool that will fit your guitar. Music stores are generally pretty bad at giving customers those tools, so if you didn’t get them with your guitar…go to the store and ask for them if your purchase was recent.
Before I start my guitar neck adjustment, I usually loosen my 3rd and 4th strings on the guitar to give me better access. You don’t want to evaluate your neck with these string loose, just have then loose when making adjustments.
Righty Tighty (Clockwise) – Lefty Loosey (Counter-Clockwise)
Remember the golden mechanical rule. Righty Tighty, Lefty Loosey. So to straighten the neck, you need to turn the truss rod counter-clockwise…to the right with the end of the hex wrench facing up.
Warning: Before you tighten the truss rod, you might want to loosen it just slightly by going to the left. Just to make sure it will move freely. Tightening a truss rod too much can cause damage to your guitar. You can break the truss rod in the neck of your guitar. Which is bad 🙂
If your guitar is brand new and the neck has never been adjusted, you are pretty safe. If it has never been adjusted you might also hear a little cracking sound as you first turn. This could just be freeing the truss rod from some excess glue from the manufacturing process and not be something to worry about. (But as always, if in doubt…take it to a repair shop and have a luthier adjust your guitar)
Depending on how warped your guitar neck was, make 1 or 2 quarter turn adjustments. Then tune your guitar back up to pitch. Not just your 3rd and 4th strings that you loosened…but all of them. Because you straightening the neck, all of the strings will now be a little higher in pitch than they were before.
If your guitar needs further adjustment that 2 quarter turns, you might want to wait at least a day before tightening the truss rod more. The wood of your guitar neck needs some time to get used to the new tension placed on it by the truss rod. Sometimes you will find that no additional adjustment is needed after the settling in period.
If you find your neck still needs straightening after going through this process a couple of times. Take it to a repair shop. Your problems are beyond the do-it-yourself level. Or one last do-it-yourself level thing to try is to put lighter strings on your guitar. So with lighter strings there is less tension on the neck. So the neck will naturally be less warped.
Back Bowed Guitar Neck Adjustment
If the strings were touching at the 5th fret when you were evaluating the neck, it could be too straight, or have a back bow like the exaggerated picture below.
If after evaluating your neck you find that there is a back bow. You can make counter-clockwise (to the left) adjustments to the guitar truss rod. But on some guitars, once the truss rod is loose, there is no where else to go. And you actually do not want to have your truss rod completely loose, it will rattle in the neck.
There are double action truss rods on some newer guitars where you can keep turning counter-clockwise and the truss rod will tighten in the other direction and you can put relief in the neck that way. But if you don’t feel the truss rod tightening up after multiple quarter turns to the left…and it just continues to loosen then you don’t have a double action truss rod.
So at that point, you can take your guitar to luthier, and they can take some more drastic measures to adjust your neck. Or one last do-it-yourself remedy it to put heavier strings one your guitar. More string tension will pull your guitar neck in the desired direction.
Adjusting the String Height at the Bridge
Only after making the proper guitar truss rod adjustment will you want to think about adjusting the height of the strings at the bridge. You might do so to compensate for buzzing on a particular string, or to try a lower the action further than a guitar neck adjustment would allow for.
On electric guitars you can sometimes adjust each individual string height independently, or on some you can only raise or lower each side of the bridge.
For acoustic guitars you would have to either shave down the bridge saddle, or build it up. So adjusting the string height at the bridge on an acoustic guitar is not something I would recommend doing yourself.
How Often to Make a Guitar Neck Adjustment
The wood of the neck of your guitar breaths and moves depending on weather conditions. Or over time string tension pulls the neck in one direction, and needs to be moved in the opposite direction with a guitar truss rod adjustment.
Or even for some cheap entry level guitars the wood for the neck was never dried properly, so in 6 month it’s all out of whack as it dries more on it’s own. So small guitar neck adjustments will probably be a normal part of your guitar maintenance just like changing your guitar strings.
Next Step in Your Do-It-Yourself Guitar Setup
Now that you have made the proper guitar neck adjustment, you will want to make a guitar intonation adjustment if you have an electric guitar.