How to Adjust Your Truss Rod to Eliminate Buzz

Adjusting the truss rod on a Nechville Phantom

Has this happened to you?  You pick up your banjo- just before heading into the jam, studio or big stage- only to find there’s a sudden fret buzz! 

Let’s take a look at the probable cause, the easy fix, and how to prevent it.

The Cause

Changes in humidity cause your banjo neck to move. This can cause the neck to bow or straighten (or back bow), allowing the string height to vary in consistency up and down the neck. The string may come close enough to the string that it vibrates against one or more frets when being played. Or the action may become unacceptably high.   

How do you measure proper bow?

Place a capo on the 1st fret and hold down the 4th string at the last fret, you should see a small gap between the string and the fret.

While the string is held down:

  • See if you can slide a business card in between with room to spare. If so, you have too much bow.                      
  • If the string is closer than a business card, or is already touching, your neck is too straight.

The Solution

Nechville banjos require a 1/4″ nut driver with a narrow shoulderThe one pictured is made by Craftsman, #41971.

If it’s a Nechville, you may not need to remove the truss rod cover screw. It is designed to swing out of the way like a door. 

If you have too much bow, turn the nut driver clockwise (start with 1/8 turn or less)

If your neck is too straight, add more bow by turning the nut driver counter-clockwise.


Carry the necessary nut driver in your case and perform this adjustment when needed, perhaps 2-3 times a year.

However, if you don’t know the business end of a 1/4″ truss rod driver with a particularly narrow shoulder here’s something that can help:

If you keep your instruments out of the case, use a humidifier in the room(s) where your instruments are kept when the air is dry. Home heating systems and especially wood stoves dry the air out considerably. 

If you keep them in their cases, invest in a guitar humidifier to be placed in the case. Several are available at local or online music retailers.  For the ultimate in-case system, Boveda makes 2-way humidity packets you can put in your banjo case. These constantly adjust to provide an ideal humidity range inside the case. If you go this route make sure to read about seasoning your case.