I just bought a Yamaha Pacifica 112V and initially had some difficulties setting up a proper relief on the neck. The neck was too straight and I could not get a proper clearance between the 8th fret and the low E  string when putting a capo on the first fret and holding down the string at the last fret. I tried adjusting the truss rod counter-clockwise all  the way until it was loose. It made the situation a little better but  the neck was still very straight. I am using 9-42 strings by the way.
I then realized that turning the truss rod even more counter-clockwise made the situation better and the truss rod started getting tighter again until it was quite firm. This leads me to believe that this guitar may have a dual action truss rod where turning it all the way counter-clockwise makes the neck more concave. This guitar is not advertised as having this feature, but I could not find any evidence that it has a single-action truss rod either.

It is my understanding that with single-action truss rods, turning it all the way counter-clockwise would simply unscrew the truss rod nut.
If anyone has any insight into this situation, I would really appreciate it.
Thank you. 
To me, this is a normal thing. I think this is something deliberate some neck builders have started doing to create sort of a "poor-mans" bi-directional truss rod, which is MUCH better than a uni-directional truss rod because it means you can adjust the upbow AND backbow of the neck. I have a Jazzmaster I built, and a Strat with the same exact neck with the same exact specs, - both chinese necks, that have this feature. I had a Pacifica 112V at one point myself and I recall having to do the same as you to get the neck right - when I sold it it was commented on as playing really great.

IIRC, Bi-Directional truss rods were created to address the problem of necks getting too much natural backbow and even twisted and not being able to fix those necks and having to replace them. It seems they also were created for the reason of people using lighter strings (.009's and lighter) as they sometimes cannot have enough pull to create enough of a relief in the neck. My 1983 Hondo Paul Dean II was this way, strung up with .012's or higher (I used Paul Dean's early 80's gauges - .013, .013, .016, .024, .034, .046 - it was perfect with 1/4 turn of the nut from loose) it's perfect, but with .009's which is what I usually use, it has too much back bow and buzzes even with only 1/8 turn of the truss rod, I can take the nut OFF and it's too solid with .008's (result of a 3 piece neck, and the darn neck is HOLLOW of all things and it's still that strong). I've thought about testing out a retrofit for older guitars that enables this capability and testing it on the PD. However, I tamed the PD's neck by string it up with .014's for awhile with the truss rod just barely set, and then getting it 100% straight and leveling the frets. We'll wait and see though. I do have the action on that thing as good as a $3000 PRS now though.

The first bi-directional truss rod I ever saw was in a Steward MacDonald Guitar Shop Supply catalog in 1996 which they were doing some kind of special feature on at the time like it was a huge deal. I never gave it a second thought till when I was building my Jazzmaster and after putting .009's on it the neck was STILL backbowed even though the nut was entirely loose - I thought it was a quality problem b/c Chinese CBS Strat copy neck, but I found out that if I kept turning, the truss rod nut would back up against the inside of the neck and push the neck straight and even add some relief if needed. Knowing this, when I used the second neck identical to the one on my Jazzmaster on my strat, I took advantage of this off the bat - both guitars have VERY low action after a fret level/recrown without buzzing as a result.

I quite love this feature, it gives me more versitility when it comes to doing setups. Weather some necks do this deliberatley, or if it's just an unintentional "feature" they added due to computer aided design/construction limitations or something, I dunno, but I'm glad it exists at least on some necks. I never thought a $60 Chinese neck could play as good as a $350.00 Plecked Warmoth, but I guess that's how you do it.
My Current Mains
- 1996 Fender Jag-Stang with EMG Pickups
- 1998 Fender Jaguar with Cool Rails
- 1982 Hondo Paul Dean II (DiMarzio Super II X2)
- 2010 "Fender" Jazzmaster (Home built)
- 2013 Squier VM Bass VI (stock)
Last edited by Mad-Mike_J83 at May 23, 2017,