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Truss Rod Adjustment

Guitar Neck Truss Rod Adjustment | Learn how to spot a bowed neck and how to make a truss rod adjustment in this guitar repair article.

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Truss Rod Adjustment

First determine where the truss rod adjustment access point is. It will be either accessed from the peghead side of the guitar neck or the soundhole side in the case of an acoustic guitar. Electric guitars  can have access at either end of the neck.

If after you remove the access plate for the adjustment nut or otherwise notice that the nut is nearly stripped, you should replace it immediately. Completely unscrew it and obtain a new nut from a guitar supply store such as Stewart MacDonald.

To aid you in the removal process, put a couple of drops of penetrating oil on the nut/washer joint and let it soak in for a few moments. Do this even if the nut looks like it is in new condition as it will allow you to make adjustments much easier.

Truss Rod Adjustment Nuts Come in Many Different Configurations Such As:
    Inner Hex Nut: This nut is adjusted by a hex or six-sided wrench. Make sure that the wrench is of proper size and that the fit of the wrench is tight with no play. If you still have play after trying all your hex wrenches, you may have to try a metric hex wrench set.
    Outer Hex Nut: This will be the most recognized adjustment nut and quite often deformed. If you need a new nut, you can pick one up at a well-stocked hardware store.
    Fender-Style Guitar Neck Bullet Nuts: Adjustable from the peghead with a hex wrench. A variation of this is a slotted bullet nut which you adjust with a straight-slot screwdriver.
    Spoke Wheel Guitar Neck Adjustment Nut: This nut has holes in the head in which you insert a small tool to turn the nut in small increments.

Now I'm assuming you have checked your neck relief. If not read my article on Guitar Neck Relief, and then come back here to continue.

The Actual Guitar Truss Rod Adjustment Process:

If you need a bit less relief in the neck, crank the adjustment rod in 1/4 turn increments and continually check your relief measurements. Be sure to do this with the strings on the instrument and "in-tune".

If you have a two way adjustment rod system, you have a great deal more flexibility and can gain more relief than the normal compression rod offers.

Usually you will be able to adjustment the neck enough by just loosening or tightening the nut.

Still a bit confused about which direction to turn? Refer to the diagram below. Right to tight and left to loosen is a good way to remember. Tighten bows up and loosen bows down.

Truss Rod Adjustment Diagram

Truss Rod Adjustment Diagram

Truss Rod Adjustment - What Happens if There is Not Enough Adjustment?

Sometime you will find that you loosen the truss rod adjustment nut all the way and you still do not have enough guitar neck relief. Or, if you tighten the rod all the way and can't get enough relief, what then?

mother of pearl inlay

Truss Rod Adjustment - Watch Those Neck Inlay When Heating or Shaving a Neck


Truss Rod Adjustment - You Do Have Other Options.
    If your guitar neck has cupping or concave one choice is to completely refret the fingerboard with larger fret wire. The "tang" is the portion of the fret that extends into the wood of the fingerboard. By enlarging this "tang" gage, you in effect, create little "wedges" all the way down the length of the fingerboard and forcing the neck to bow in the opposite direction. This often corrects the concave condition of the fingerboard and once again the truss rod becomes effective.
    Be careful when considering a new fret job. See my article on Refretting Your Guitar-Neck before you attempt this.
    A second option is to actually remove the strings and the frets and plane the convex or concave condition right out of the fingerboard itself. You do have to be careful with this method as you are thinning the fingerboard and if there are pearl or other inlays in the fingerboard, you run the risk of sanding through them.
    This is one of the best fixes for this condition though and the one that I would consider over the other options.
    A third possibility is to place a heated guitar neck straightener on the fingerboard and heat up the fretboard to a point that the glues soften between the fretboard and the neck. Then let the heating iron cool until the glue resets and the neck is straight.
    The problem I have with this method is that through the heating process is that the fretboard dries and shrinks to an extent that frets pop out. Another thing is that this does not seem to fix the problem long-term. The wood tends to find it's way back to the per-heated condition.
    Also, if you are unsure if you have plastic inlays in your guitar neck rather than mother of pearl or abalone, if you heat the plastic inlays you will destroy them.
    I will admit that this may be the best method for inexpensive guitars and you wish to save some money.
Truss Rod Adjustment - What if You Have An Inexpensive Guitar?

Lastly if you have an inexpensive guitar with a neck that runs all over the place like a roller coaster, you may be forced to take the frets off the guitar and sand or plane the fingerboard flat.

Sometimes these truss rods are installed improperly and do not function properly. Also, a guitar like this may not be worth the expense of an operation like this as the value is just not justified.

Click HERE to go back to Guitar Neck Relief Article