The coordinator rod system is a patented Gibson feature and makes it possible for a banjo player to adjust the string action to a desired height. However, adjusting the coordinator rods tends to have a negative affect on the banjo by putting undo stress on the rim, which can cause the rim to “egg” and the tone to suffer. Because of this, many banjo players prefer to keep their coordinator rods in “neutral”. This has since become a general rule of thumb for many areas of life.
The coordinator rod system consists of two rods, two small washers, two large washers, and three nuts. Some earlier coordinator rods featured the “long nut” which made the rod adjustable in length. Gibson later dropped the long nut in favor of a fixed length rod.
Coordinator rod system with long nut.
Coordinator rod system without long nut.
Coordinator Rod Assembly
On the neck side, the two small washers fit over the neck lags that the rods screw onto. On the tailpiece side, the two large washers and two nuts push against the rim to secure the rods. The rod closest to the resonator goes through the rim and secures the tailpiece bracket with the help of the third nut.
Long Nut Coordinator rod system.
Coordinator rod system without long nut. Gibson’s final prewar design.
Tailpiece bracket secured by coordinator rod nut.
Gibson catalog description of the coordinator rod system.
Single Rod System
Non-Mastertone Gibson banjos use a single rod system with one long rod and a nut to secure the neck to the rim.
Single rod system.
Early Rods
In the early 1920’s, Gibson used 1/4″ rods and the long nut. The rod closet to the head was known as the “rim bar” and the rod with the long nut was the “co-ordinator rod”. There was a threaded hole through the flat in the center of the rod. The threaded hole in the rod would accept the bolt that attached to the “New Professional Special Resonator”, Gibson’s first resonator. The purpose of the long nut was to allow side-to-side adjustment of the rod so the threaded hole would be in the middle of the rim to line-up with the bolt that was in the center of the resonator.
When the “arched and laminated” wooden resonator was introduced, The threaded hole and the flat were not necessary. When gibson introduced the 5/16 inch diameter rod, they got rid of the flat in the center of the rod but not the long adjusting nut. This was most likely a mistake which they later fixed.
Earliest 1/4 inch rod system with threaded flat.
Long nut allows for threaded flat to be centered for resonator bolt.
Resonator bolt attached to rod.
Second generation 1/4 inch rod system with no flat.
Second generation 1/4 inch rod system.
Gibson catalog description of first double rod system.