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Truss Rod Adjustment

What does a truss-rod do?

Varying climate conditions and string tension will combine to bow a fretted stringed instrument's neck. Fortunately most contemporary instruments (as well as a great deal of vintage ones) are equipped with an adjustable truss rod. The adjustable truss rod is designed to allow a qualified person to counter the bowing of a neck with a good eye and a few turns of a wrench. By tightening the nut on a truss rod the neck will straighten or overbow (become convex) if overtightened. The two functions of an adjustable truss rod are to reinforce the neck and give the owner some wiggle room to counter climate changes.


The Truss-Rod Nut on a Gibson is accessible at the headstock where it is hidden beneath a bell shaped plastic cover. We refretted this Gibson Les Paul Custom and fabricated a new nut for it.	The Truss-Rod on a Martin guitar is adjusted from inside the guitar. This photo shows the end of the truss- rod and the truss rod nut before this new neck was set.

Why is a truss-rod necessary?

Most truss rod adjustments are made necessary by the changes in relative humidity that come with seasonal changes in climate. Many players have a difficult time maintaining a consistent environment for their instrument of 50% relative humidity year round (the relative humidity that most fretted stringed instruments are built to sustain). Therefore it is quite common for player's instruments to require multiple truss rod adjustments in a given year to counter the effects that humidity changes have on an instrument's neck.


Fender Guitars of yesteryear (and reissue Fenders such as the one pictured above) have a truss rod nut which is accessed at the neck pocket end of the neck. Most contemporary Fender electric guitars and basses have a truss-rod which is adjusted from the headstock. We also refretted this Fender Jazzmaster.	Larrivee Guitars have a truss-rod which is adjusted inside the guitar. On these instruments the truss rod is actually recessed into the neck block. Although this design is good for structural stability, it is difficult to adjust if you don't have the special allen wrench that comes with each Larrivee from the factory. This guitar also recieved a new bone saddle.

Will a truss-rod adjustment always straighten a neck?

Unfortunately the truss rod will not correct all bowing that fretted stringed instruments develop. If under bowed (concave) enough even the truss rod will not properly straighten the neck. Though a good guitar will last a life time if properly cared for, it is likely that at some point the neck of the instrument will need to be straightened using more drastic measures.


Rickenbacker Bass. This bass guitar has two truss rods, which we adjusted during the course of a nut repair and refret.


Adjusting a Taylor Truss Rod. Taylor guitar's come equiped with a truss rod that is adjustable at the headstock. We adjusted this Taylor guitar's truss rod during a set-up with fret leveling.	Musicman Sting Ray Bass. The truss rod on this bass guitar is adjusted at the body-end of the neck. The truss rod nut has holes in it so the neck may be adjusted without removing the neck from the bass's body. We adjusted this bass during a set up.