Non-functioning truss rod question

[inadu ridge]

So, I bought a used 2001 Tacoma JM9 sight unseen, no return possible (yeah, I know DUMB). Guitar is cosmetically excellent and sounds great. First thing I notice when I tuned it up is very high amount of forward neck bow. I took that out with a few turns of truss rod. Fine. After a couple hours playing, the neck bow is back. Took that out with another couple of turns. A couple of hours later neck bow is back and truss rod is at it's limit.

What is the likely problem with the truss rod? Broken? Stripped? etc.
Can I diagnose the exact problem myself?
This should be repairable, right? About a $200 job if someone has to remove fretboard, right?

Any info will be appreciated.

IR

[Wade Hampton]

If the truss rod moved and the relief in the neck changed, only to return after a while to to where it had been, that suggests to me that the anchor of the truss rod is slipping. The anchor is at the opposite end of the truss rod from where it’s adjusted.

It’s not supposed to slip, obviously, and it’s not designed to be accessible: on a Tacoma guitar it’s deep within the neck/tailblock area. The fingerboard will have to be removed to get to it.

If that’s the situation with your guitar, then it’s a fairly dire problem, and a difficult and costly repair. I’m dealing with the exact same issue with one of my guitars.


Wade Hampton Miller

[inadu ridge]

Thanks Wade. That was my idea as well. It's like the anchor point is slipping. Oh well, lesson learned.

[Wade Hampton]

Yeah, it’s no fun. I just got the exact same diagnosis yesterday on my Guild twelve string. Guilds have a dual truss rod system in their twelve strings’ necks, and while the truss rod on the treble side of my guitar is fine and functions as intended, the bass side truss rod is doing exactly what you described on your Tacoma: it shifts the relief for a few minutes, then returns to where it was.

If the threads on the truss rod were stripped out, it wouldn’t be adjusting at all, so it’s the anchor.

Like I said, no fun.


whm

[mirwa]

Your description of events makes me believe its not a truss rod issue, maybe you have a lifting bridge, maybe you have a collapsing top, maybe you have neck wood with the wrong grain direction.

I recommend you see a local luthier, most of us do obligation free quotes.

Truss rod.
When an anchor is failing, typically the action cannot be adjusted with the neck in tension, the anchor will rotate within its cavity.
When a adjustment nut fails, it seizes solid or snaps off
When a truss rod cannot be adjusted further its indicative of the nut having travelled to the end of threaded section.

Steve

[inadu ridge]

Originally Posted by mirwa

Your description of events makes me believe its not a truss rod issue, maybe you have a lifting bridge, maybe you have a collapsing top, maybe you have neck wood with the wrong grain direction.

I recommend you see a local luthier, most of us do obligation free quotes.

Truss rod.
When an anchor is failing, typically the action cannot be adjusted with the neck in tension, the anchor will rotate within its cavity.
When a adjustment nut fails, it seizes solid or snaps off
When a truss rod cannot be adjusted further its indicative of the nut having travelled to the end of threaded section.

Steve

Let me reiterate the sequence of events with more detail.
Guitar was shipped detuned somewhat. Upon tuning to standard, it was noticed by sighting down the neck from the headstock, that there was a huge forward bow (a curvature) massive relief in the neck.
Tightening the truss rod flattened the neck (lessened the relief), and the guitar played well for a couple of hours. Then, the forward bow returned. The truss rod was tightened again and the neck flattened again. After a couple more hours playing the huge forward bow returned again. The truss rod nut at this point reached it's endpoint and would not allow any more turns.
The bridge is not lifting and the top is not sinking.

[mirwa]

See that is an odd situation to happen and not indicative of a truss rod failure.

A truss rods purpose is to add additional strength back into a neck after shaping the neck to a point where it can no longer hold its shape with a string load.

By your description, the truss rod is working, 3 times you have adjusted it and three times it reduced the relief, now in a very short period of time, it has reached its max travel, without seeing the guitar this is very indicative of a flat sawn neck situation which is rectified with carbon fibre rods or a new neck.

It may be something else, it may even be some odd ball situation with the truss rod, a local luthier will be able to give you a definitive answer in minutes of assessing the guitar in their hands.

Steve

[inadu ridge]

Okay, Thanks Steve.
Tacoma generally used fine woods and the mahogany neck on this one looks fine grain-wise.
You are correct that I just need to take the instrument to a competent repair person and get an assessment. I was just hoping that maybe I could diagnose the exact cause of the phenomenon myself.

Thanks,

IR