By Dan Erlewine. Although it can help by fixing the curvature in the neck and creating a more comfortable string height, you may want to try adjusting your bridge before you go fooling with your truss rod. What makes a truss rod adjustment necessary? The neck can also bend more or less than it would do usually if there is a change to a different gauge of guitar strings. A Truss Rod is the adjustment bar inside your guitar neck, also referred to as a tensioning bar. If you don’t, the nut can be damaged when you try to turn the wrench. Below, James "Skitchy" Zimmers from our PRS tech center (PTC) explains the signs that you may need a truss rod adjustment, as well as the tools required to safely adjust your own truss rod. So, the fundamental tools that you will need to adjust your truss rod are: Martin switched to the 2-way adjustable truss rod in 2006. Guitar necks are made of wood which naturally twists and warps between the varying humidity of the seasons. The amount the rod must be turned will vary according to the type/quality of truss rod and amount of adjustment necessary. The same is true of Fender- and Gibson-style truss rod bolts. Truss Rod. If you are wondering what truss rod adjustment tool you would need in order to adjust your guitar truss rod you have come to the right place. The video below provides a great overview of what a Truss Rod is and the purpose they serve. First things first. Adjusting the truss rod with the instrument tuned to pitch will allow us to gauge our progress and continue re-checking relief before making further adjustments. When a quality guitar leaves the factory, the truss rod is adjusted according to the maker’s taste in setup specs. Cody Arsenault of Musicians Tuts explains how to fix an upbow and backbow in a guitar's neck by making some simple DIY truss rod adjustments. I am going to help you to find the right tools to adjust your truss, whether you are playing: an acoustic guitar, electric guitar or even a bass guitar. The truss rod isn't exactly meant to fix your action. But a change in string gauges, climate (especially a change in humidity), or simply the player’s taste may require an adjustment, even on a new guitar. Every PRS guitar we ship comes with a small wrench used for adjusting your guitar's truss rod. These have been around since the early ’20s. What year is your guitar? An old-school truss rod bolt at the bottom of the neck (Image credit: Future) When you’re adjusting the truss rod, make sure the Allen key is seated properly in the truss rod nut; push it all the way in. The older 1-way rod is just past the #1 cross brace. Its sole purpose is to allow you to adjust your guitar neck against the pull of your guitar strings. That one sits right at the edge of the dovetail, so it takes a 4.5" long wrench to reach it. Truss rod (n) - Stabilizes and adjusts curvature or relief of a guitar neck.