For many guitar players, their guitar's truss rod is a largely misunderstood device. Some people are terrified of touching their guitar's truss rod while others believe it to be a magic exlir … adjust it often enough, and the truss rod can solve all the problems in their tone.

The truth is that the truss rod is a simple device that has one purpose: to counter the pull of the strings. It isn't meant to adjust the height of your strings; you can't set your intonation with it; and unless you do something unusual, you aren't going to ruin your guitar trying to adjust it.

Gibson applied for the first truss rod patent in 1921. Until then, guitars had bigger, thick necks to handle the tension of the strings. Basically, the mechanism is simply a steel rod with an anchor at one end and an adjustment nut at the other. It is buried (usually in a curve) in the center of the guitar's neck. Tightening the adjustment nut pulls the rod straight, thus straightening the neck. Loosening it allows the neck to pull up with the influence of the string tension, allowing the neck bow. To this day, most truss rods remain relatively unchanged. There are several versions of a two-way rod, rods that can move a neck both toward and away from string pull, but most are still the "old style", and that's what will be covered here.

• You tighten the nut (clockwise) to reduce relief (front bow).
• You loosen the nut (counter-clockwise) to get more relief (back bend).

All the truss rod does is counteract the pull of the strings. When you loosen the adjusting nut the strings supply the pulling force to add the relief. If you have light strings it may change the amount of relief you get or how long it takes to see it. Don't expect it to happen instantly. It takes a while for the wood to change in the neck.

REMEMBER: "righty tighty, lefty loosey!"

Here is a graphic to help you understand:

If the adjuster will not turn any more because it is adjusted to the end -- you might need a shim washer:

Here's what Fender has to say about adjusting the Truss Rod on a Telecaster:

Truss Rod

There are two different styles of truss rods found on Fender guitars and basses; the "Standard" truss rod and the "Bi-flex" truss rod. Most Fender guitars and basses are equipped with a "Standard" truss rod (there are two types of "Standard" truss rod; one which adjusts at the heel of the neck and one which adjusts at the headstock, but both operate on the same principle). The "Standard" truss rod can counteract concave curvature, for example: in a neck that has too much relief, by generating a force in the neck opposite to that caused by excessive string tension.

Fender also uses a unique "Bi-Flex" truss rod system on some instruments. Unlike the "Standard" truss rods, which can only correct a neck that is too concave (under-bowed), the "Bi-Flex" truss rod can compensate for either concave (under-bowed), or convex (over-bowed) curvature, by generating a force in either direction as needed for the correction.

Check your tuning. Install a capo at the 1st fret, depress the 6th string at the last fret.

With a feeler gauge, check the gap between the bottom of the string and the top of the 8th fret -- see the specification chart below for the proper gap.

Adjustment at headstock (Allen wrench): Sight down the edge of the fingerboard from behind the headstock, looking toward the body of the instrument. If neck is too concave (action too high), turn the truss rod nut clock-wise to remove excess relief. If the neck is too convex (strings too close to the fingerboard), turn the truss rod nut counter-clockwise to allow the string tension to pull more relief into the neck. Check your tuning, then recheck the gap with the feeler gauge and re-adjust as needed.

Adjustment at neck joint (Phillips screwdriver): Sight down the edge of the fingerboard from behind the body, looking up toward the headstock of the instrument. If the neck is too concave (action too high), turn the truss rod nut clock-wise to remove excess relief. If the neck is too convex (strings too close to the fingerboard), turn the truss rod nut counter-clockwise to allow the string tension to pull more relief into the neck. Check your tuning, then recheck the gap with the feeler gauge and re-adjust as needed.

Note: In either case, if you meet excessive resistance when adjusting the truss rod, your instrument needs constant adjustment, adjusting the truss rod has no effect on the neck, or you're simply not comfortable making this type of adjustment yourself, take your instrument to your local Authorized Fender Service Center.

Neck Radius 7.25" 9.5" to 12" 15" to 17"

Relief .012" (0.3 mm) .010" (0.25 mm) .008" (0.2 mm)

Thanks to TDPers JWells and 0leFuzzy and to the Fender Musical Instrument Corporation and others for the information and graphics contained here.