Adjust your Bow (truss rod)!






One of the most confusing things about good guitar adjustment is the bow of the neck and it’s controlling device: “The Truss Rod”. Like all things, once you know how to fool with it you discover it’s not brain surgery and it’s ridiculous to pay someone money just to wail away on an Allen wrench. The theory is that all necks need a little bit of bow or curve to avoid unwanted buzzes or dead notes. This is usually the case, but my ’62 Tele is dead flat and it sits right up and howls with nary a buzz. I’ve had some Gibsons that were that way, too—and I’d swear that Ibanez has mastered the dead flat, no-bow neck. Having said that, your guitar probably needs a little, so how much is enough and how do we adjust it?

I’m glad you asked.

With the exception of very old vintage guitars and some el-cheapo plywood ones, every guitar (electric and acoustic) has a mysterious metal rod buried under the fingerboard just like Egyptian King Anatoep’s buried gold under the…oops! Almost gave that one away! Really—it’s under there and it’s there for one reason. The concerted pull of all six strings brought up to pitch puts about 220 lbs. of pressure on the neck. The strings are continually pulling the head of the guitar towards the body. To fight this, manufacturers put an adjustable rod in the neck. Many things contribute to the forces on the neck: extreme temperature change, changes in humidity, and loaning your guitar to Pete Townsend.

As a general rule, the amount of bow needed in the neck varies between guitars but here’s the starting place: We need to check what you got, baby! Grab your axe, Eugene, and hold it just like you were practicing. Tune it up to correct pitch (“open” E,A,D,G,B,E low-to-high). Now we are going to “sight” the neck. All those guys at Guitar Center who look down the neck from the head with one eye squinted are fooling both you and themselves. You can no more “see” the curve of the neck correctly from the head than you can look down a hot desert road and see that it’s still straight at the horizon—it’s an optical illusion created by the way the eye works. We’re going to “sight” the bow from the side—where the curve is actually seeable—it’s just subtle. Now, with the guitar where it’s supposed to be, fret the first fret of the big “E” with your left hand and fret the last fret of the same string with your right hand simultaneously. Look at the 12th fret. Look at the gap between the bottom of the string and the 12th fret (the metal). Don’t got any? You don’t have any bow and some of your frets are probably buzzing like chainsaws. Most guitar manufacturers want you to have about 3/16ths gap there but that’s always too much. Here’s the deal: for most guitars, the thickness of a nice, normal business card is the right amount. So, take the card that you got from that hopped-up guy in the bar who told you he’s a big-shot producer out of your wallet, slip it into the gap at the 12th fret. If it fits with a light amount of drag, you’ve got the right amount. If it doesn’t fit—we’ll adjust the rod. Important reminder: this works for electric and acoustic guitars both. Does this remind you of setting the spark-plug gap on some new plugs? Me, too.

Okay, we’ve got to assume that you, or your bass player, just got back from humid Japan and you or her stepped out of the plane into hot, dry, Texas and all of a sudden your strings are laying flat on the frets making slapping sounds like Bootsy Collins. Just like divorce, we adjust.

Now that you have an idea that your bow is not acceptable, we will change it. Most likely we’ll need an Allen wrench but some Fenders need a phillips screwdriver. We need to find the adjustment screw that’s at the end of the buried rod. It can only be one of two places: one end of the neck or the other. (Boy, I love how that “logic” stuff works). On a lot of basses and guitars, the Allen rod adjustment is in that divot behind the nut, usually covered with some fancy plastic logo. A lot of Strats have it right out in the open. On most acoustics, you can see it in the sound hole where the neck joins the body, which means to adjust it you’ll have to remove a few strings to get to it. Bummer. On the majority of Telecasters, the danged thing is at the end of the neck where the neck joins the body so you have to undo the screws holding the neck enough to expose the adjusting screw. To make matters worse—it’s usually a phillips-head screw thingy. Don’t panic! No matter where it is, you can get to it and reassemble the guitar with no ill effects. Trust me. If you can eventually figure out how to get to the SID card in your cell phone—you can find your rod adjustment. Just be patient.

Okay. Locate and identify your nut. Because sometimes it is. A “truss rod” nut, I mean. Some guitars have an actual nut at the end of the buried rod. We don’t care. Whether it’s an Allen key, a screwdriver, or a nut wrench—it’s probably sitting in dad’s tool box. Once you figure out which one it is, make sure it’s the right size. An Allen wrench that’s “pretty close” is not close enough. Once we got the right tool, we’re going to turn it. When you slot the tool in, your hand becomes a clock (no matter where the slot’s located). If you need MORE bow—turn it counter-clockwise. If you want less, clockwise. Turn in quarter-turn increments: nice and gentle. Some rods are tough because they’ve been sitting in Uncle Fred’s closet for forty years. Good ‘ole American persistence is needed. You want to sneak a little WD40 in to loosen it up? Fine. Just don’t leave any on the finish. Do the adjust in quarter-turns. Do a quarter, sight the neck. Do another quarter. Sight the neck. Do it until that gap is where you want it to be. You’re not going to hurt anything. If you are doing an acoustic and have to loosen strings to get your tool in, so be it. That just means you’re going to be tuning up, checking the gap, loosening the strings, turning the key, tuning up, checking the…you get the picture. Ditto if you’re a Tele owner. Check the gap. Loosen the neck. Adjust that stupid screw. Re-tighten neck. Check gap again. Over and over till it’s right. Your guitar will thank you—your ears, too.

All things being equal, you should be able to adjust your bow…BUT! All things are not equal! Like I said before, if you can get a guitar close to dead flat—you’re going to have an easier playing guitar. So try it. You can always go back. Also, some guitar players like a little buzz (like me). One listen to “Funk 49” tells us that Joe Walsh personally adjusts his bow for just a little kiss of funky rattle. Am I going to argue with Joe?

So, we know how to adjust our truss rod. We know how to adjust it to alter our neck bow. How often do we need to do this maneuver? As often as you like. Obviously, if you’re only gigging at Gino’s on the weekends and the weather is pretty constant, your neck may not change for decades. However, what if you’ve used light gauge strings forever and you read somewhere that your favorite guitarist will only play on strings the size of the cables holding up the Bay Bridge and you want to try that? Bigger strings—more tension. Adjust the Truss Rod.

That should do it! Happy strumming!


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