Fender Standard Precision Bass Short-Scale Owner Manual - Page 11

Under normal tension, the neck should have a slight concave curvature. By creating a counteracting force, the truss rod prevents the neck from bending excessively under the stress placed on it by the strings. The tension on the rod is adjustable so the correct curvature can be achieved by regulating the neck's resistance to string tension. To check the truss rod setting, tune the bass to playing pitch. Install a capo at the first fret, depress the 4th string at the fret where the neck joins the body. Using a feeler gauge, check the gap between the bottom of the 4th string and the top of the 8th fret. The recommended string clearance should be approximately .015-.020" (.4-.5 mm). If an adjustment is necessary, start with the following. For basses with a headstock truss rod access, insert the 5mm Allen wrench (supplied) into the truss rod adjustment hole. Rotate it gently until you feel it engage in the hex socket. For basses with a truss rod access at the heel of the neck, perform the same operations with a Phillips head screwdriver. If the neck is too concave, turn the wrench/ screwdriver clockwise. If it is too straight or convex, turn the wrench/screwdriver counterclockwise while periodically checking the gap with the feeler gauge. Caution: DO NOT continue adjusting: 1) If extreme resistance is felt while adjusting in either direction, or 2) If the neck has a convex bow that remains when the 9