Repairing an Acoustic Guitar Neck With Shims

An acoustic guitar neck endures a lot of stress and tension.

Guitar necks endure a lot of stress from string tension, weather and humidity, and general wear and tear. If you discover that your guitar has become more difficult to play, the first thing is to set the truss rod properly so that the neck is not over bowed or under bowed. If this fails to correct the problem, then it is time to correct the angle of the neck by adding a shim. However, this is only an option if the neck of your acoustic guitar is screwed on since the first step involves removing the guitar neck. The necks of many acoustic guitars are glued and not screwed or bolted on. A glued neck should only be removed by a professional to avoid damaging the guitar.

Things You'll Need

• Screwdriver
• Old credit card
• Scissors

Instructions

1. Loosen and remove the strings from the tuning posts. Turn the tuners on the left side of the headstock clockwise to loosen the strings and the tuners on the right side of the headstock counterclockwise to loosen the strings. Pull the strings out of the tuning posts. It is not necessary to remove the strings from the guitar. Leave them attached to the bridge and saddle.

2. Unscrew the neck of the guitar. The screws securing the necks of some acoustic guitars, such as Taylor guitars, are installed on the front of the guitar at the 14th fret. The necks on other acoustic guitars are bolted to the back of the guitar.

3. Determine which part of the neck needs to be raised and adjusted. The placement of the shim depends upon the necessary adjustment. If the low E string sits higher than the high E string, the shim should be placed on the side of the high E string. If the high E string is too high, place the shim on the side of the low E string. If the strings are higher where the neck joins the guitar, the shim should fit in the pocket closest to the sound hole. If the strings become lower where the neck joins the body, then the shim should fit the opposite side of the neck pocket.

4. Make a shim for the guitar. The shim does not have to be very thick to raise the angle of the neck. It should be no more than the thickness of a credit card or two pieces of masking tape. Cut an old credit card with a pair of scissors. The length of the shim depends upon the purpose of the shim.

5. Place the shim in the appropriate space of the neck pocket. The shims do not need to be glued. They are held in place by the tension of the neck and they may need to be adjusted until you find the appropriate angle. Carefully place the neck back in the neck pocket. Secure it with the screws.

6. Re-string the guitar. Tune the guitar to standard pitch, E-A-D-G-B-E. Inspect the spacing between the strings and the fretboard to determine if the shim took care of the problem or if the neck requires more fine tuning and adjustment. Unfortunately, adjusting the shim requires repeating the procedure and slightly altering the position of the shim, adding a second shim, or replacing the original shim with a smaller one.

References

• Project Guitar: "Neck Shims, Placement and Purpose;" Brian Calvert
• Guitar Repair Shop; "Acoustic Guitar Neck Re-Sets;" Steve Carmody
• Chicago Luthiers: How To Reset A Guitar Neck