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Fixable?

Discussion in 'Luthier's Corner' started by Tao4Now, Sep 15, 2008.


  1. Problems with the neck of my '89 Precision Plus.

    Truss rod turns, but will not adjust. I think the headstock end of the truss rod is supposed to be pushing against this thing below, but it's begun to extrude from the truss rod socket:

    Neck002.

    Is it fixable? Is it something I can do, and if so, how would I? Can a luthier repair it? If so, how much can I expect to pay?
     
  2. Thirty-two views and no one wants to take a stab at this thing?

    It's just a Fender P, nothing exotic. I thought for sure there'd be someone here who could give me at least a clue where to begin.
     
  3. I'm not a truss rod expert. Personally, I'd take it to a luthier
     
  4. lethargytartare

    lethargytartare

    Sep 7, 2004
    Chicago
    Wisest thing is like Bassguitarbubba said -- take it to a pro.

    My amateur thoughts on it -- first, I'm not sure that cylinder of darker wood has any structural relation to the truss system. Figure, the neck is maple, and the truss has to bow that whole piece of maple, so it's braced against the wood of that piece itself -- take a look at pics (there must be hundreds here) of people building a neck with a truss, and you can see how it's braced on either end of the channel in the wood.

    Let's start simple: how do you know you NEED to adjust it? is it really really tight, but you still feel the neck has too much relief? I've had at least one neck that had a broken truss, but was in perfect position and was stable, and could be set up fine. But I also got in a fight with another neck, and snapped the truss nut off...which means I really should have been putting my efforts in to a different path on that one :(

    Can you give us a measure of the relief when the neck is at full tension (that is, the strings are tuned up)?

    If you don't want to get that involved, some other thoughts: if the nut seems to tighten and loosen, but just stops pulling on the neck at some point, maybe a thread on the nut or rod got stripped -- you can replace the nut, but the rod is a whole expensive ton of work more. Is it just that you can't tighten it any more but want to get more back-bow -- it might be bottomed out, and that might mean the neck just needs other work to allow it to be set up properly (that was the case with my neck above). Does it turn the exact same in either direction, but never comes off and never tightens -- then it's probably fully stripped.

    post some more info...

    cheers!

    ltt
     
  5. lethargytartar: take it to a pro.

    Yah. I'd still rather fix it myself if it doesn't require special tools. I'm pretty handy and reasonably intelligent and figure if I can get my head around what's going on I might be able to do it myself.

    I figure I'll get more enjoyment out of a bass I've worked on myself, but I hope I'm smart enough to know when I'm out of my league as well... hence the OP.

    lethargytartar: first, I'm not sure that cylinder of darker wood has any structural relation to the truss system. Figure, the neck is maple, and the truss has to bow that whole piece of maple, so it's braced against the wood of that piece itself -- take a look at pics (there must be hundreds here) of people building a neck with a truss, and you can see how it's braced on either end of the channel in the wood.

    I'm not sure either, that's why I asked. It is obvious that the piece shouldn't be extruding like that, and the only pressure I could think of that would cause such a thing would be from the truss rod pushing it out from the inside.

    On the heel end, the truss rod is either braced against or screws into a metal disk. Here's a picture:

    Neck010.

    lethargytartar: how do you know you NEED to adjust it? is it really really tight, but you still feel the neck has too much relief? ... Can you give us a measure of the relief when the neck is at full tension (that is, the strings are tuned up)?

    When strung, the guitar has far too much relief in the neck - as if the truss rod were providing no tension at all against the strings. I didn't measure relief before destringing and disassembly, but it was about half an inch at the eighth fret. Far too much to be playable even on the first three frets.

    The truss rod adjustment nut offers some resistance to turning - about what I expect from a functioning one: not loose, not a strain, but a fair amount of resistance. I can hear a subtle squeak as of metal against wood as it turns. It offers the same amount of resistance in both directions. I can see the rod turning inside the pocket shown in the photo above as the adjustment screw is manipulated.

    Turning provided no relief (pun fully intended). I suspect the guitar has spent a long time in this condition. Here is a photo down the neck, unstrung. As you can see, there is still a fair amount of relief.

    Neck115.

    lethargytartar: Does it turn the exact same in either direction, but never comes off and never tightens -- then it's probably fully stripped.

    That would truly be major blowage. Twenty-two fret P-bass necks aren't that common.

    Thanks for the reply, BTW. I appreciate the support.
     
  6. lethargytartare

    lethargytartare

    Sep 7, 2004
    Chicago
    good pics and info! And I get scolded for this sometimes, but I really think it's worthwhile to try work like this when you have the initiative -- as long as you can afford the risk. Learning this stuff is fun, and can save you a lot of money in the long run...anyway...

    I was really just musing about that darker cylinder that's pushed -- mechanically, I can't think of any way that tightening the truss nut would cause that. A scary thought is that it might have been in some "hostile" environmental conditions that caused the wood to shrink or expand in such a way that caused that. Have you tried pushing it back in? maybe brush it with a little superglue or wood glue, and shove it back in place -- I really can't imagine that would hurt anything. Or pull it completely out and see if that lets you see more of the situation.

    So the truss -- I think the problem is the fact that you can see the ROD turning -- it's fortunate that chunk was removed. Here's where my inexperience limits my input, but I don't think any truss rods are threaded at the terminus, with the nut being fixed -- the nut should move, the rest of the rod should be stationary. So my guess at this point would be that the nut has siezed up, and you are ONLY turning the whole rod -- and that's why you're getting no action on the relief.

    (BTW: that pic of the neck's relief was perfect -- your description was clear and accurate, but if anyone had a doubt, that pic backs up the description.)

    So, if it were my bass, first I'd try to drizzle oil or some lubricant behind the nut, trying to get it on the threads, and let that soak in. Then with some needlenose pliers, pinch the base of the rod (this is starting to sound very vulgar) and try to get the nut loose. then possibly take the nut off completely, and get plenty of lubricant, maybe even anti-sieze lubricant, on the threads to let it work again.

    Another potential scary thought -- the base isn't supposed to turn, so the fact that it does might mean that the wood that used to hold the base in place has been gouged and damaged enough to allow the whole rod to turn in place. If that's the case, even well oiled, the truss might not be able to tighten up properly. In THAT case, I might forceably bend the neck, tighten the nut, etc. -- that is, don't rely on the tightening of the nut to create the back-bow, but rather just tighten it to retain the level of backbow I forceably put in it...very unpleasant thought, but if the alternative is a $300 repair to a neck that's only worth $150 (I'm just making up numbers there), then attempting drastic steps might be justified. OR, you could try to drizzle epozy or slightly thicker superglue into the base area, using that open spot where you can see the rod, and see if you can toughen up that base area and stop the rod itself from rotating.

    Some of these ideas make sense?
     

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