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grumol

dual action truss rod on jtv59

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am i the only one who didn't know this? -- i flew from the desert to the great lakes, and after a bit noticed a lot of string buzzing, figured the truss rod needed adjusting, so i wanted to back off on the truss rod adjustment, give the neck a slight relief, since it had none at all, but found the adjusting hex nut already slack, as in, no tension, and a slight turn clockwise did nothing - -- so turning a little more clockwise, i start getting tension, but of course, wrong tension -- - took about an hour before i remembered that some guitars have a dual action rod, i.e., it gets tighter in both directions, and theres a neutral spot where it just spins -- i guess the extreme humidity change had allowed the rod to enter the neutral position -- finally got up the courage to begin turning counter clockwise, fearing that i'm undoing the nut off the end of the truss rod, and sure enough, it went through the neutral zone, and then started tightening, this time giving the slight bit of relief i needed

 

but you all know this, right? -- anyway, love this guitar

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Counter clockwise loosen and allows relief, clockwise tightens,

taking away relief leveling/flattening the fret-board.

 

Extreme care should be taken when doing this to a guitar with a set/fixed neck.

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Give the neck some time to settle after every quarter rotation. It could need hours or even a day in some cases, especially when you adjust a baseball bat, like the neck of the 59.

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thanks, the small increments, letting it settle part i knew, but this is the first dual-action rod i've dealt with, i just assumed the 59 had single action 

 

"baseball bat"? -- well, i wouldn't go that far, i think its meant to mimic a 59 lp, not an earlier -- but i can say that coming from a 70s hagstrom swede, it was a change, but overall a comfortable one, once my hand adapted to it -- i had initially planned on shaving the neck, but now i wouldn't touch it, too concerned that it is where that beautiful sound, even unplugged, is coming from

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I'm not sure what you mean by dual-action rod? According to psarkissian, it seems to be a standard rod that tightens in one direction and loosens in the other. That's consistent with my 69 and 89 which both adjust at the headstock.

A neck that I got from Warmouth has a twin truss rod, but it has two access points. One at the heel, and one on the lower side.

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I'm not sure what you mean by dual-action rod? A neck that I got from Warmouth has a twin truss rod, but it has two access points. One at the heel, and one on the lower side.

Dual action truss rods can push or pull...they can force more relief into the neck if necessary (in the case of a back-bow), whereas the single action rods can only exert force in one direction, tightening from a neutral position and pulling the neck back (opposite the direction of string pull). Once they're loosened to that neutral position, they can no longer provide any more relief for a neck that is either pin-straight, or has a back-bow. Dual action rods can push the neck forward, creating relief. It's a better design...particularly for a set-neck guitar. If a neck develops a back bow and it has a single action rod that is as loose as it gets, then that is huge problem that requires major surgery to correct, usually at a considerable cost. For all but the most valuable/cherished instruments, this usually results in a one way trip to the toothpick factory. The dual action rods pretty much eliminate this scenario, unless the damage is very extensive.

 

The second adjustment screw on your Warmoth is just a feature of that particular design, provided so that you don't have to remove the neck to make adjustments, as the main adjustment screw is at the heel and nothing at the headstock...but it's not required, per se. There are plenty of guitars out there with dual action rods that have just the one adjustment screw.

 

I never understood necks that only adjusted at the heel. I had an older Warmoth like that once, on a Strat i had bought second hand...but who the hell wants to un-bolt the neck every time you need to give the truss rod a 1/4 turn? Predictably, over a number of years of repeatedly removing the neck bolts, one of the holes got stripped and had to be doweled and re-drilled. It's a stupid design.

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but you all know this, right?

 

Actually, I did not know this either. @psarkissian, could you confirm the JTV-89F also has a dual action truss rod? The only info I can find is this:

 

"(for JTV 89F)
1 - 4mm hex, for truss rod adjust JTV-89F (relief)"
 

Thanks.

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well, i'm not the voice of authority on this, but i can confirm it, at least on my 59, having worked on my own guitars for years, and this being the first dual action rod i've come across -- it is exactly as cruisin described, it both pushes and pulls, and therefore it is able to remove a backbow -- i have an old matsumoku washburn that has a single action rod, and when the rod was totally slack and tuned to pitch, it had a back bow -- if this had been the rod in my 59, i could have continued turning counter clockwise from the slack, neutral, position, and it would have begun tightening again, this time removing the backbow and increasing relief -- but as it was not dual action, i sanded the maple fretboard to remove the slight back bow, and played it that way for years

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All the JTV's use the same truss rod.

Anti-clockwise for relief, clockwise to take relief out.

4mm hex tool is in the hex kit that came with the guitar.

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All the JTV's use the same truss rod.

Anti-clockwise for relief, clockwise to take relief out.

4mm hex tool is in the hex kit that came with the guitar.

Yes...but which direction to turn it to produce a desired effect was never the question. "Counterclockwise to add relief" describes every truss rod on earth, whether it's dual action or not. However, there are those that can exert force in both directions and those that can't. There is a fundamental difference in design that's completely independent of which direction to turn it to make the necessary adjustment. Righty tighty, lefty loosey... that never changes.

 

Single action rods only provide relief by RELEASING tension, and only to a certain point...once all the tension has been released, you're SOL if the neck still doesn't have sufficient relief. Dual action rods can force additional relief by pushing the neck forward, in the same direction as string pull.

 

He's asking which type is in there...

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Thanks grumol, I don't doubt your experience. I just wanted a representative from Line6 to confirm it. I did find find one post (http://line6.com/support/topic/786-truss-rod/?p=4119) from 2013 (which no one responded to) where oskvarek43 called Line6, only to hear "the rep seemed to think it was dual action." 

 

Yes...but which direction to turn it to produce a desired effect was never the question. "Counterclockwise to add relief" describes every truss rod on earth, whether it's dual action or not. However, there are those that can exert force in both directions and those that can't. There is a fundamental difference in design that's completely independent of which direction to turn it to make the necessary adjustment. Righty tighty, lefty loosey... that never changes.

Single action rods only provide relief by RELEASING tension, and only to a certain point...once all the tension has been released, you're SOL if the neck still doesn't have sufficient relief. Dual action rods can force additional relief by pushing the neck forward, in the same direction as string pull.

He's asking which type is in there...

 

Thanks Cruisinon2. That is exactly what I was asking.

 

Do the JTVs have a dual action truss rod? A response from any Line6 representative that can confirm or deny the JTVs have a dual action truss rod would be appreciated.

 

Thanks

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Thanks grumol, I don't doubt your experience. I just wanted a representative from Line6 to confirm it. I did find find one post (http://line6.com/support/topic/786-truss-rod/?p=4119) from 2013 (which no one responded to) where oskvarek43 called Line6, only to hear "the rep seemed to think it was dual action."

 

 

Thanks Cruisinon2. That is exactly what I was asking.

 

Do the JTVs have a dual action truss rod? A response from any Line6 representative that can confirm or deny the JTVs have a dual action truss rod would be appreciated.

 

Thanks

Don't be surprised if you don't get an answer. The powers that be have a peculiar aversion to divulging innocuous info... particularly anything that even vaguely relates to setting up a Variax.

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another way of putting it, is that a dual action rod tightens in both directions, i.e., righty tighty, lefty tighty -- only the resulting force being applied is reversed

 

if you try that with a single action rod, you'll unscrew the nut, which is why i was initially hesitant to continue turning

 

again, this is a superior design, so don't think it needs to be kept a secret

 

of course, it is possible that this feature was added by world musical instruments, i believe the korean manufacturer, and line 6 wasn't aware of it -- but judging by the quality of their instruments, world doesn't seem to need any guidance in their craft

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another way of putting it, is that a dual action rod tightens in both directions, i.e., righty tighty, lefty tighty -- only the resulting force being applied is reversed

Technically speaking yes, you are correct. As far as which direction to turn it to produce more or less relief, though...it's always the same, no matter what the design...clockwise for less relief, counter-clockwise for more relief. That's all I meant, though I should have been more precise.

 

The cloak and dagger nonsense baffles me too...I'm reasonably certain that saying "yes it's a dual action truss rod" won't cause the earth's magnetic field to reverse itself, but it will likely be treated as a State secret nonetheless...

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from the prs site:

 

The PRS double acting truss rod provides neck adjustment in both directions. Conventional truss rods can only compensate for forward neck bow. Due to varied climate and other conditions to which your PRS guitar may be exposed during its lifetime, we have made our necks fully adjustable. 


PRS switched over to the double acting truss rod about halfway through the 1992 production year. To determine whether your guitar has this system simply examine the adjusting nut. The single acting rods used a brass adjusting nut threaded onto a steel rod. The double acting rods use a steel nut fused to a steel rod. 

Neck adjustment can be accomplished as before except that a reverse bow can now be fully corrected. The double acting truss rod achieves twice the amount of adjustment as the single acting rod with the same amount of movement of the adjusting nut. Do not over-adjust!

 
interesting, prs se guitars are supposedly made in the same korean factory

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Yes,...

Stew-Mac catalog refers to it as a two-way rod.

Dan Erlewine refers to it as a dual-action.

All JTV's use the same rod.

 

Clockwise to take relief out, anticlockwise to add relief in.

Do it in 1/8 turn increments and let it sit for a day.

 

Torquing  too much one way, and then the other over short

periods is a good way to warp a neck.

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