Do I need a neck shim?

[giannifive]

I just got my new baby delivered today: a 2004 RG2570! It came in the factory box, so I assume it was set up at Ibanez. The set up was pretty bad. So of course the first thing I did was take the guitar apart. After I took the neck off the body, I discovered there was no neck shim inside. This is contrary to everything I've read about new Ibanez's sold in the US, which is that they all have neck shims in the pocket, closest to the bridge. Anyway, here's a side view of the neck on the body, will full tension on the strings:



As you can see, the neck is much higher on the bridge side of the pocket than the nut side. And as I said, there is no shim in the neck pocket.

Even with the bridge pretty high (and consequently the action pretty high), the strings still buzz on frets 12-23. It seems that this is due to the neck angling back, away from the body. I should mention that the trem is level, and the neck seems to have the right amount of relief.

So my question to all the expert jemsiters is: do I need a neck shim? I've read up on how to do it, and it seems easy enough. Just slip some business card thickness paper in the neck pocket, near the end closest to the nut.

Has anyone else had this experience with a new Prestige Ibanez?

[Rich]

Did you test it first to see if it needed one?

[giannifive]

How do I test to see if it needs one? Do I need one only if I can't get a perfect fourth of pull-up? I get just under a perfect fourth now.

If a neck shim is only needed to adjust the amount of pull-up, then I guess it's fine. But it means I'm doing something else wrong with my set-up, because the neck seems to need some pretty high action to get rid of the buzzing on frets 12-23.

I'd better go buy a feeler gauge so I can actually measure the action, but I'd guess by eye it's at least 2.5mm at fret 24...

[Rich]

Neck shim only controls pullup range and has nothing to do with buzz. Try straightening your truss rod.

[giannifive]

Does the truss rod change the shape of the neck for the frets above 12? I always thought the truss rod only affected frets 2-12, and that any buzzing on frets 12-23 is caused by the bridge being too low. If that's the case, then could I have a kinked neck? On a brand new Prestige!

Anyway, I will try adjusting the truss rod when I get home from work tonight.

[Rich]

It does if you have way too much relief. It's not affecting so much neck shape there, but the action too low for the amount of relief is the probem.

[jem7vwh93]

You say the bridge is adjusted high and the frets still buzz. You may need to adjust the truss rod as Rich says and put in a shim. I find my Ibanez guitars need truss rod adjustments seasonally.
I usually try to get it dead straight. With the action too low all frets should buzz equally. If only the high frets buzz - too much relief, if only the low frets buzz not enough. But if they all buzz equally - neck is dead straight, and the bridge is too high, then I put in a shim.
All guitars could need shims with the exception of glue in or god forbid your favorite neck through.
I finish by adjusting the truss rod for slight relief.

[giannifive]

It turned out I was actually getting some buzzing on all frets for my low strings. I guess I just wasn't hearing it before... And also my guesstimate of 2.5mm was action was quite high. It was actually 1.7mm.

So what I did was raise the bridge and loosen the truss rod a hair. The relief is now just over 0.5mm measured at fret 9 with 1 and 24 pressed down. The action is 2.3mm bass side, 2.0mm treble side measured at fret 24. I get only minimal buzzing now on frets 2-10 on only my low E string with "heavy" pick attack. There's no buzz anywhere else.

So it sounds like if I straighten the neck and lower the bridge to decrease the action and I get equal fret buzz on every fret then I may need to shim the neck pocket. Thanks for the tip!

One last question, how tight should the neck screws be tightened after reinstalling the neck? I have a habit of stripping wood screw holes, so I was very careful about this. I tightened until the screw was just barely in contact with the metal grommet, then tightened a quarter turn. I also used a criss-cross pattern, and started with one of the screws closest to the bridge.

What are the signs that the screws are too loose/tight? What are the long-term consequences of them being too loose/tight?

P.S. For an AANJ, always be careful to make sure you put the longer neck screws in the bridge-side holes, and the shorter ones in the nut-side holes. I accidentally started putting a longer screw in the short nut-side hole before I realized my mistake. I assume if I had tightened it too much it might have popped out a fretboard inlay or maybe even popped off the fretboard!

[jem7vwh93]

<<So what I did was raise the bridge and loosen the truss rod a hair. The relief is now just over 0.5mm measured at fret 9 with 1 and 24 pressed down. The action is 2.3mm bass side, 2.0mm treble side measured at fret 24. I get only minimal buzzing now on frets 2-10 on only my low E string with "heavy" pick attack. There's no buzz anywhere else.>>

I read an article way back in the 80's where Vai suggests lowering the action so the buzz is not audible through the amp. So some acoustic buzz can be expected especially with a heavy pick.

<<So it sounds like if I straighten the neck and lower the bridge to decrease the action and I get equal fret buzz on every fret then I may need to shim the neck pocket. Thanks for the tip!>>

If you can lower the bridge such that it does not feel too high, then don't shim. In theory neck and body contact area should be maximized for improved tone and sustain. Shims decrease contact area. I leave them out whenever possible.

<<One last question, how tight should the neck screws be tightened after reinstalling the neck? I have a habit of stripping wood screw holes, so I was very careful about this. I tightened until the screw was just barely in contact with the metal grommet, then tightened a quarter turn. I also used a criss-cross pattern, and started with one of the screws closest to the bridge.

What are the signs that the screws are too loose/tight? What are the long-term consequences of them being too loose/tight?>>

The neck on my white jem shifts in the pocket slightly if the screws are loose. So I tighten just until there is no slip. If your method above accomplishes this than I'd say it's as good as any.

<<P.S. For an AANJ, always be careful to make sure you put the longer neck screws in the bridge-side holes, and the shorter ones in the nut-side holes. I accidentally started putting a longer screw in the short nut-side hole before I realized my mistake. I assume if I had tightened it too much it might have popped out a fretboard inlay or maybe even popped off the fretboard!>>

EEEK! - Yes - whenever I take apart anything with more than a couple pieces I lay them out in exploded view (just made that up) in front of me and think through how it goes back together.