The saga continues... (v68)

[sloop_john_b]

For the past few months, I've been SLOWLY (quarter-turn every day/every other day) trying to get the neck on my v68 dead flat so I can give I a proper setup. But it's just not getting there.

The E-A side is bowed and the truss rod nut is starting to get mighty tight.

The D-G side has BACKBOW and the truss rod nut is now completely loose.

The strings are light gauge D'Addario Chromes.

What the heck is going on?

[jps]

This is the one that Larry Davis removed the fingerboard and did that work on the truss rods near the body, right?

[sloop_john_b]

This is the one that Larry Davis removed the fingerboard and did that work on the truss rods near the body, right?

That is correct Jeff; thread here: viewtopic.php?f=2&t=382014&start=30

[jps]

Hmm, so his fix didn't work.

[johnallg]

Pull the pickguard, look at the rod acorn nuts, and see if they are moving into the wood again.

[deaconblues]

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[sloop_john_b]

Not sure how deep exactly they're supposed to be in there, but here:

And the view from the top:

[sloop_john_b]

Dan...I think that's pretty much where this is headed.

[jps]

The acorn nuts look like they are the same distance in; IIRC, didn't Larry put a metal plate set in a little bit into the neck like a 1/2" or so, which would make the location of the nuts seem about right? I have had basses where one of the TR nuts was fully loosened (actually, barely finger tightened) and the other with some tension on the rod and seemed to be okay. Have you removed the nuts and tried repositioning the spacer block?

[cassius987]

In my experience one rod can sometimes be doing all the work; that's how my 4001FL is, and the only rod that is tight is just barely tight. Yet the neck is practically flat and with pretty hefty strings installed. Some necks are just really rigid and don't need a lot of help to flatten. I would focus more on how the neck is behaving than the way the truss rods seem to be based on the hex nuts. Either way do not gauge whether the neck is bowed or not based on the truss rods; use a real measure of the bow, like the string-as-straightedge method which I find extremely reliable and fast.

What was it like when you got it back from Larry? Both sides bowed? In a case like this I would think about taking all the tension off the rods and starting over, if you think you "brought it" to this point from a better situation. On the other hand this kind of behavior immediately smacks to me of "bad fingerboard" as I have seen a couple of cases of it, Ric and non-Ric. You could do a fret job to "patch" it but the better way is to replace the fingerboard. Is it possible Larry's was green wood or otherwise unsuitable and he wouldn't have caught it? (Not a dig at Larry! Just an honest question.)

Lastly I would caution you against seeking a "dead flat" neck. A little relief is perfectly okay; I'm sure you know this from your P Bass. Ric bass necks really aren't special, they don't have to be set dead flat to work right. I think the only time "dead flat" becomes an important issue is if you have a bad neck angle because it really "shows off" the relief. In that case setting the neck dead flat can mask the neck angle a bit, instead of having to countersink the bridge, but I ended up countersinking on my 4001FL instead and I'm a lot happier with the result.

[Wiker]

That does not look good.

When tightening the nut you're trying to force the rod through the spacer block at an angle, which will of course make it very hard to turn the nut. Dragging the rod through the block at an angle will also probably damage the treads, making it even harder to turn the nut over the stripped threads.
Even if it feels "mighty tight", the feeling probably comes mostly from forcing the rod through at an angle, not from the rod actually being at high tension. There might not even be much real tension on the rod.

Before anything else I think this problem should be fix to make sure the truss rods are actually functioning. I saw from the old thread you linked to that Larry D. fixed it back then, but the fix probably didn't hold up after all.

Been through this problem myself
viewtopic.php?p=682766#p682766

[johnallg]

I think Geir brings up a good point. I'd back off the nuts, get the block back where it should be, snug both nuts up to the block, then start to adjust the neck flat.

You might also consider taking this to Chris to let him try to re-balance and get the neck to behave. Short hop down the freeway.

[Wiker]

Before anything else I think this problem should be fix to make sure the truss rods are actually functioning. I saw from the old thread you linked to that Larry D. fixed it back then, but the fix probably didn't hold up after all.

Btw, I don’t think it was a bad fix. It simply turned out not to hold up over time. The first fix I did on my bass using very hard plywood didn’t hold up either. I’m sure Larry can improve the fix without any other disassembling than removing the nut.
(Just wanted to avoid any misunderstanding )

[sloop_john_b]

Should I keep the strings tuned up or leave them slack?

[Wiker]

Yes, just slacken the strings. Remove the truss rod nuts and push out the spacer block to see if it has started to sink into the wood on one side, or maybe the block simply didn’t sit right.