Guitar Making and Repair/1980 Rickenbacker bass dual truss rods
I actually have several questions. I purchased this bass (used) in 1986 and have enjoyed playing it since. From the beginning of ownership, any adjustments to the bass had been performed by luthier Phillip Petillo until his passing a few years back. Since then, I have not felt comfortable with anyone else. About 1 year ago, while making an adjustment, I snapped the adjuster nut on one of the rods. I had difficulty getting the socket on due to the thrust plate had tilted and the ends of the rods had bent in towards the neck. I removed the rods, re-threaded them, then re-installed them. After adjusting the neck straight (as is my understanding) the bass was great for a long while. The bass then stayed in its case for a few months. When I removed it from its case to play it again, I found the neck had bowed. When I removed the name plate I found the thrust plate had tilted again and the ends of the rods have bent in towards the neck again. So before I do anything further I wanted to ask: 1- Have I done something incorrect? 2- Is the thrust plate tilting and bending the truss rods a common problem? 3- How long are the truss rods brand new? 4- Not knowing if this repair had been done in the past, before I came into ownership of this bass - Can the truss rods be cut too short? 5- If they can be too short and need to be replaced, can you offer any suggestions - I have found they are not available. I would appreciate any help, suggestions, and information you could offer. Thank You.
First off, you didn't snap the nut--you snapped the truss rod by tightening the nut too much, correct?
So, you shortened and re-threaded the truss rod. Hopefully you did the same thing to both to even out the stresses?
Sometimes, depending upon the strings used and the tension put upon the neck itself, the neck will require so much truss rod compensation that the rods and thrust plate will distort. Since your bass was already 5-6 years old when you got it, chances could be that at one time, high-tension strings were used (often Rotosounds). These older Ricks with their double-action truss rods are susceptible to the kind of distortion you describe whenever their dual-action truss rods are overtightened. Later Ricks (post-1985ish) with single-action rods are more forgiving.
How do you tell if your Rick has dual or single-action truss rods? Look at the end of the fretboard where the neck joins the body, just above the neck pickup. If you see two acorn hexnuts buried in a recess in the fretboard/neck end, you have a later- single-action truss rod model. If all you can see are two rectangular slots about 3/16" X 5/16", you have an older Rick with dual-action "hairpin" style rods.
As long as you haven't shortened the truss rods by more than about 3/4", you're in safe territory. Any more and you'll have issues. The original hairpin rods were in the range of 23 3/4" --23 7/8" in length. They need to mass of the neck heel to brace the hairpin end; if they're cut more than once, they lose too much length and will eventually result in an "S" curve in the neck bow or relief.
The old-style rods can be bought new from me for $210.00/pair if all else fails.