Truss Rods Adjustment

By Denny Rauen

When a truss rod is in good working order it’s easy to make adjustments. If the rod is not working properly it’s impossible to balance the instrument. This is one of the most common serious problems that I come across. I would have to say one out of every ten instruments have some kind of truss rod problem. These are usually attributed to one of three things. A jammed truss rod, a truss rod that has severely corroded, or a truss rod that was improperly installed at the factory. There are far too many types of truss rods to cover them all in one article so I will refer to traditional truss rods found in many American built instruments.
You should not have to be a member the Olympic weight lifting team to adjust a truss rod. Jammed truss rods are common and relatively simple to get working.

The following is a technique I have developed to remedy this problem.

1. Remove the truss rod nut and washer
2. Clean out cavity and threaded rod
3. Hold the instrument upright and carefullydrip lubricant (WD40,etc.) into the cavity.
4. Allow the lubricant to flow down the rod for a couple of minutes. Sometimes it helps if you first, slightly heat the rod with a soldering iron.
5. Reinstall the washer and nut.

Now, upon tightening, the neck should easily be adjusted into a reverse bow. For necks that don’t respond the repair is a bit more involved as the truss rod is either thoroughly corroded or was not installed properly and thus does not have enough leverage. You can never be sure why some knuckle head let a neck with a faulty truss rod into production but what ever the reason I’ve seen it on many old and new instruments. There is a degree of inherent strength with a new neck but over time as the wood fatigues the neck relies on the truss rod for leverage to keep the neck straight. In instruments where the truss rod is installed wrong the rod will have to be removed and the channel will need to be reconstructed properly before installing a new truss rod.

For best results be sure that the new rod is installed within 3/16 of an inch from the back of the neck (see drawing). Doing this will create the kind of leverage needed to easily counter the tension of the strings. In the process of doing this repair I have come across some of the industries highest priced instruments with trussrods installed so close to the fingerboard that they were useless in countering the string tension. I have also seen instruments that must have been used to tap beer kegs. The truss rods were so thoroughly rusted they had become one with the wood.