Adjusting the truss rod in your electric guitar.
Before we adjust the truss rod, we should take a look at what the truss rod is and it's purpose in a guitar neck. A truss rod, essentially, is a metal rod that is inserted into a channel or cavity in the neck to help with reinforcement. Truss rods stiffen the neck and help eliminate relief and back-bow in the neck. More "modern" truss rods not only help reinforce the neck but also help bend the neck back into a straight position.
There are many different styles of truss rods that have been popular over time. The early truss rods were not adjustable. Early Martin guitars had a variety of different truss rods. These truss rods were often a T-bar or piece of square tubing. The primary purpose for these truss rods was to stabilize the neck and keep it from bowing. If the neck did bow because of extreme weather conditions or faulty craftsmanship, there was nothing you could do to fix the neck short of tearing it apart, straightening the neck, and inserting a new truss rod. Martin used these non-adjustable truss rods up until 1984. For more information about the history of Martin guitar truss rods, please visit the Martin truss rod page.
Today, almost all guitars are fitted with adjustable truss rods. Adjustable truss rods can be adjusted using an allen wrench or screw driver in either the nut or the heel of the neck. Electric guitar truss rods come in two main styles: single action or one-way truss rods and dual action or two-way truss rods.
In short single action truss rods bend the neck one way by tightening the truss rod. Loosening a single action truss will not "bend" the neck in the other direction; it simply relieves the pressure from the truss rod and allows the string tension to bend the neck in the opposite direction.
A dual action truss rod, on the other hand, does bend the neck in both directions. Tightening or loosening a dual action truss rod will bend cause the truss rod to bend in either direction. For more detailed information about how truss rods work, please visit the truss rod page.
Steps to adjusting the truss rod in your electric guitars.
Step 1: Check the relief or back-bow in the your guitar neck.
With a straight edge-
Checking the straightness of your neck is relatively simple if you have a straight edge or a notched straight edge. Simply play the straight edge against your frets or fretboard and shine light behind it. If the neck is not straight, light will shine through the gaps.
Without a straight edge-
If you do not have a straight edge, you can simply use your strings as a straight edge. Press down the string at the first fret and press down the string on the fret where the body and neck meet. The string will become a straight line between the two frets. You may want to use capos to hold the string down. Once the string is fretted on two frets, you can measure the distance between the frets and the string with feeler gauges. If there is relief in the neck, the 6th or 7th fret will have the most distance between the string and the fret. The distance between the string and frets will decrease the closer you get to the capoed frets. The opposite will be true if the neck has back-bow. If the distance between all the frets and the string are equal, the neck is straight and does not need to be adjusted.
Remember as I wrote on the action adjustment page, there is no right or wrong amount of relief in your neck to an extent. Usually a slight amount of relief is appropriate. Just like anything else in adjusting guitars, neck relief is a player's preference. It depends on the style of instrument and player. You should try to adjust your truss rod until your neck is flat and play it. Then you can continue to add a slight amount of relief until the neck feels comfortable. Since the neck changes with the seasons, this adjustment will be fairly often. You will get used to how much relief you prefer in your neck. The average relief at the 7th fret is about .007 inches.
Step 2: Adjusting the Truss rod.
Before we adjust the truss rod I want to warn you. BE VERY CAREFUL. Do not over tighten the truss rod. Remember the truss rod is a piece of metal that we are applying pressure to in order to bend it and the neck. If you over tighten the truss, you can cause any number of problems. You could snap the truss rod, warp the fretboard, or twist the neck. All of these problems are rather involved and expensive repairs. It is best just to be careful and not over tighten the truss rod in the first place.
A good thing to do before following the steps below is to loosen your truss rod a full turn and measure the neck to see what happens. If the truss rod is already all the way tightened and the neck still has relief in it, you may break something by continuing to tighten the truss rod beyond its limits.
There are two basic styles of truss rod placement: Fender Telecaster and Gibson. The Fender Telecaster style placement has access to the truss rod in the heel of the neck. The Gibson style has access to the truss rod in the headstock/peghead. Here are the steps to adjusting both of these truss rod setups.
Different Styles of Electric Guitar Truss Rods.
How to adjust a Fender Telecaster Style truss rod.
The Fender Telecaster truss rod is accessible at the bottom of the neck. It cannot be adjusted while the neck is still firmly attached to the guitar because the screw head is partially hidden by the body. Listed below are the steps to adjusting this truss rod.
- Loosen the strings.
- Loosen the two neck bolts farthest away from the headstock/peghead all the way.
- Loosen the two neck bolts closest to the peghead 1/3 of the way.
- Carefully, pry back the neck away from the body exposing the truss rod screw.
- Use a flat-head screwdriver to turn the truss rod screw right or left. BE VERY CAREFULLY of the screwdriver hitting the body of the guitar. Also, be careful not to slip with the screwdriver and dent the body. Only turn the screw 1/8 of a turn at a time. Tighten the truss rod screw to eliminate relief in the neck or add back-bow. Loosen the truss rod screw to add relief in the neck.
- After you have turned the screw 1/8 of a turn, tighten the neck bolts and retune the guitar. It is important to have tension on the neck. Without the string tension on the neck, you cannot see the extent to which you are moving the neck with each truss rod adjustment. Then you can measure the relief in the neck.
- Repeat these steps as much as necessary until your neck is straightened.
If you do not feel comfortable prying back the neck and adjusting the truss rod while the neck is partially attached, you may complete remove the neck and make your slight adjustments; however, you will not be able to check your adjustments until you reattach the neck, retune the guitar, and measure the relief. This way will just take more time, but it can be done.
How to adjust a Gibson Style truss rod.
The Gibson style truss rod is accessible through the headstock/peghead. This truss rod is much easier to adjust than the Fender style truss rods. Most guitars today have a truss rod installed with adjustment access in the headstock/peghead. Most guitars also have a decorative truss rod cover to hide the access to the truss rod. Here are the steps to adjusting a Gibson style truss rod.
- Tune the guitar to pitch. It is important to have tension on the neck. Without the string tension on the neck, you cannot see the extent to which you are moving the neck with each truss rod adjustment.
- Remove the truss rod cover by unscrewing the screws with a micro-screwdriver.
- Lubricate the truss rod nut is possible/necessary.
- Only turn the screw 1/8 of a turn at a time. Tighten the truss rod screw to eliminate relief in the neck or add back-bow. Loosen the truss rod screw to add relief in the neck.
- After you have turned the screw 1/8 of a turn, retune the guitar. It is important to have tension on the neck. Without the string tension on the neck, you cannot see the extent to which you are moving the neck with each truss rod adjustment. Then you can measure the relief in the neck.
- Repeat these steps as much as necessary to straight the neck.
- Replace the truss rod cover.
With all truss rod adjustments, do not drastically adjust the truss rod. Sometimes it takes time for the neck to settle into its new shape. If it feels like you keep having to tighten or loosen the truss rod for a single adjustment, retune the guitar to pitch and let it sit for a few minutes. This will give it time to settle into its new shape.
Remember, the truss rod adjustment is only one step in lowering or adjusting the action on your guitar. Do not keep adjusting the truss rod if the action is not ideal. All the truss rod does is straighten the neck. The rest of the steps to completely setting the action on your guitar can be found on the adjusting guitar action page. I cannot stress enough to be careful while adjusting the truss rod. There are many highly involved and expensive problems that you can cause by over-tightening the truss rod. For more information about fixing broken truss rods and problems that can be caused by over-tightened truss rods please visit the truss rod repairs page.