Help orienting / installing a truss rod.

Hey guys, hopefully you can help me out with my first truss rod installation.

The rod I recieved in the post today ( a bi-flex version) is not familiar to me, so I want to make sure I put it in properly.
I will be installing it under a glued on fretboard (in a straight channel)

It looks a little something like this:
http://img.photobucket.com/albums/v652/sloth86/closeup.jpg?t=1238618100
The threaded rod is brazed at both ends to a square section.

Since it will be going in a straight, flat-bottomed channel I am tempted to put it in with the square, flat-bottomed section at the bottom.
However, if I do this, it seems as if adjusting the nut will have the opposite effect to what is traditional in a truss rod.

Allow me to demonstrate. Turning the nut clockwise gives this:
http://img.photobucket.com/albums/v652/sloth86/clockwise.jpg?t=1238618102

Counter-clockwise does this:
http://img.photobucket.com/albums/v652/sloth86/anti-clockwise.jpg?t=1238618104

I've never seen a truss rod out of a neck before, so what I'd like to know is:

1) Is this rod suitable for my application?
2) If so, have I got the right idea as to which way up it should go?
3) If not, (Argh!) what would work best for me?


Thanks in advance,

Mr. B

1) Is this rod suitable for my application?
2) If so, have I got the right idea as to which way up it should go?
3) If not, (Argh!) what would work best for me?

1) Should work.
2) Good question. What you have to consider is that once installed the two rods won't be able to separate as shown in your pictures. Some dual action truss rods actually have the two rods in heat shrink tubing. Thinking about this is giving me a brain ache. You can probably identify. I suggest you do the following: Get some sort of tape and tape the two rods together at a few points. Then turn the adjusting nut and see which way the two rods bend together.

I suggest you do the following: Get some sort of tape and tape the two rods together at a few points. Then turn the adjusting nut and see which way the two rods bend together.


Ah, thanks. That was the bit I was missing.
Having tried the tape, if I put the square section at the bottom I will have to turn the nut counter-clockwise to counteract the string pull.
I'll just have to make sure I write it down somewhere on / near the guitar once it's finished. "counter-clock to counter-act...counter-clock to counter-act" Sounds like a mantra I could manage. :wink:

Let's think about this. Looking at your adjuster, I see it has left hand threads.....

......http://img.photobucket.com/albums/v208/jwells393/NewAlbum2/LeftThreadAdj.jpg

.....so, when you turn the adjuster clockwise, the upper rod should get longer resulting in the rod going convex on the round rod side. Seems to me, if the rod is being installed from the fretboard side the square bar should be on the back side of the neck and turning the adjuster clockwise would correct too much relief with is the normal truss rod adjustment .............. unless I'm missing something.

Looking at the smaller threads, they look to be right handed ....... now I'm really confused ........ don't know what's going on inside that large cylinder. When you turn the adjuster clockwise, which way does it bend?

now I'm really confused ........

Join the club! :roll:

don't know what's going on inside that large cylinder. When you turn the adjuster clockwise, which way does it bend?

When the adjuster is turned clockwise the smaller right hand thread is dragged into the cylinder, shortening the top rod in relation to the bottom (square) one and causing the whole assembley to bend upwards.
In my book that is still backwards from 'normal'.

As for what happens inside the cylinder, I'm almost tempted to cut it open and put us out of our misery!
It's very late in the day for me (after midnight now) and thinking about what goes on in there is not getting me anywhere. All I have to show for my bafflement is a few scrawled diagrams, scribbled out in frustration.

The best I can come up with is that the larger section of thread has a nut at the end which the smaller thread screws into. The nut turns with the large thread and drags the small one inside it.
At the same time the larger thread is drawn out of the cylinder due to the direction of its thread, adding to the shortening of the top rod.

Incomprehesible? Probably. I'm going to bed now. Maybe I'll wake up with a sensible answer tomorrow...Maybe.

Hey I'm not a guitar builder but...

since it's a bi flex truss rod, and is able to bend the neck in either direction, I do not think there will be an obvious way to see which way it goes in the guitar by examining it. Maybe the best thing is to contact the manufacturer and ask if there is a 'right way up', or if it doesn't matter?