Truss rod
It is an adjustable steel or graphite bar in the interior of the neck. The truss rod strengthens the neck and helps it to bear the strings’ tension.
TRUSS ROD
It is possible to adjust the truss rod with a screwdriver or an Allen key depending on the bass model. The truss rod regulates the neck’s curvature. Adjusting the truss rod and the bridge it is therefore possible to set the desired strings-fingerboard distance (action).
The truss rod is also helpful in maintaining the right curvature of the neck when changes in temperature or humidity occur.
The screw or bolt that regulates the truss rod is at one of the two ends of the neck, either next to the headstock or to the body. Normally turning it clockwise increases the tension and turning it counter clockwise relaxes the tension.
TRUSS ROD’S ADJUSTMENT WITH ALLEN KEY
TRUSS ROD’S ADJUSTMENT WITH A SCREWDRIVER