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Problem with neck - pictures

Discussion in 'Hardware, Setup & Repair [BG]' started by pc131, Nov 20, 2012.

  1. pc131


    Nov 20, 2012
    Hi all

    I have some problems with neck in my bass. Bass is Polish hand made P/J copy by Mensfeld. It looks like:



    I got this bas for free from someone who was not using it (has other basses), but it has problem with neck, which is curved in this way:


    The action on 10th fret is about 10~12mm! At higer frets (~20) the action lowers a bit. At first frets action is also rather low. But at middle the neck is curved back and the action is terrible. But when I take off strings, the neck is straight!

    My neck has tensioning rod regulation at body side:

    The rod with nut:

    The rod without nut:
    o852iv. .

    Now, when the nut is turned on the rod to the max of thread, I cannot turn the nut more clockwise, because I am afraid I could break something. But as the neck curves back when the strings are on, I think the rod is not tensioned to the maximum, but how can I tense the rod more if the nut will not go, while reaching thread end...

    Any help appreciated
  2. abemo


    Feb 27, 2012
    Arvada, co
    First thing I would do is remove the nut and rub a bit of vaseline (or lubricant of choice) on the threads. This will help extend the life of the truss rod, and make adjustments easier. Next, when you tighten the truss rod, try to put some pressure down on the back of the neck, so its already flexed in the direction you want it to move, again, the reduce strain on the truss rod while adjusting it. Third, if your threads are maxed out and the neck is still bowed, try to add a shim to the neck, or add a washer or two behind the nut. Adding the shimm will change the overall andgle of the neck, lowering the action towards the body, adding the washers will give you more space to adjust the rod without maxing out the threads.

    Good luck.
  3. ShirazBop

    ShirazBop When the going gets weird, the weird turn pro Gold Supporting Member

    Sep 29, 2006
    Greensboro, NC
    I've seen this pressure applied by my techincian in Ft Worth,...he called it a "heart message",...
  4. abemo


    Feb 27, 2012
    Arvada, co
    I bought a late 70's, pre-lawsuit era MIJ j neck copy a few months back and had to heavily lubricate the threads as well as apply back pressure just to get the truss adjusted, it was a similar situation where the tension on the nut was way higher than I was comfortable with adjusting. Worked like a charm.
  5. pc131


    Nov 20, 2012
    Thanks abemo.

    I used luquid spray (lubricant) that I use for rusty nuts. I put this spray on threads and on the trust ord itself, so the liquid spray flows down on the rod (the neck is standing on the head on the carpet). In my case, the nut is screwed all the way onto all threads and cannot go more clockwise, the tip of the trust rod (the threads part) is touching the bottom of the nut, the bottom which is in the middle of nut, the same bottom that I touch with regulation tool:


    I am not sure how it works.... So when I turn the nut clockwise, it (nut) should stay in the same position in correspondence to the neck (just turn, not move up or down) and the trust rod is being moved by in the direction of body, and the neck is being curved, so the 1st frest go down and middle frets go up? Do I get it? It works like that?

    I am not sure what kind fo trust rod do I have, there is one:



    This is rather not my trust rod, because in this case (first picture of the two above), the nut is moving along with the threads, causing the upper part of trust rod to bend, and bending the neck, but in my case, the nut cane be turned but the rod with the threads is not turning. I get mess, how it is working...
  6. abemo


    Feb 27, 2012
    Arvada, co
    Yes, as you tighten the nut the truss rod will add pressure toward the fretboard (backbow, essentially the opposite to the pressure put on the neck by the strings) which will help hold the neck straight when the strings add pressure to the neck (forward bow). Sounds like you might need washers.
  7. Ewo

    Ewo a/k/a Steve Cooper Supporting Member

    Apr 2, 2008
    Huntington WV
    Tightening the truss rod nut will reduce the neck relief--flatten out the bow in the middle of the neck. If you've bottomed out the nut on the rod, you're smart to have stopped trying to tighten it! Probably the wood of the neck has compressed, over time, under the nut. The cure is to add a washer or two under the nut, as someone (edit: abemo) mentioned before. You might have to grind the washer(s) down a bit to fit in the channel around the threaded end of the rod.

    One thing I can add, though: shimming the neck does not address a playability issue caused by too much neck relief. That's the fix for a different problem.
  8. pc131


    Nov 20, 2012
    By washers, you mean:

    If you look closely at picture:
    the trust rod is how to say that.. the trust rod is the inner threads which goes all the neck to the head side, and the outer part, the "pipe" which also I think goes all the neck to the head. When I turn the nut clockwise, to bend the neck in opposite way the string tense the neck, the inner part of rod is coming to the body, but how inner and outer parts of trust rod work at the other end? Are they soldered? If soldered, then it sould not mov at all, if not soldered the inner trust rod ... eghhh I have no ide how it works. Anyway I should try washers, and maybe new nut, because this one is little broken on upper side where I put the regulation tool (how you name it?) to turn the nut... I think current nut is now working because as I wrote, the tip of inner trust rod (this with threads) hits the bottom in the nut - if you know what I mean, then the washers might help...
  9. pc131


    Nov 20, 2012
    If you've bottomed out the nut on the rod, you're smart to have stopped trying to tighten it!

    You mean: if I/somebody loosened/unscrewed the nut on the rod, there will be problem tightening it, because the wood over time changed structure?

    But there were no washers under the nut to this day, and the nut cannot be screwed more clockwise, because inner rod hits something in the inner middle of nut, and the strings bend the neck, so? Production problem? Longer nut needed? Or maybe on the opposite side of rod moved in the wood of neck and nothing more to do?
  10. Ewo

    Ewo a/k/a Steve Cooper Supporting Member

    Apr 2, 2008
    Huntington WV
    When the truss rod nut has been tightened as far onto the threads as it can go, putting more force on it is likely to snap the threaded part off.

    Have you tried clamping the neck straight (strings off), then gently trying to tighten the nut a bit more? IOW, as others suggested above, "help" the neck into being less bowed first, then snugging the truss rod nut to hold that position. That puts far less stress on the truss rod than trying to get the truss rod to pull the bow out of the neck just by itself.

    You can use a carpenter's level as a rigid straightedge. Lay it on edge on the frets, pad the back of the neck carefully (use small blocks of wood to avoid marking the neck), and use woodworker's clamps to ease the frets to the straight line of the level. Then see if the nut can be tightened a bit more.

    The basic idea is like this. Once the bow is out of the neck, you can see if the rod is capable of any more adjustment.
  11. pc131


    Nov 20, 2012
    I was helping the neck being less bowed when I was screwing the nut clockwise. I used not the washers (I couldn't find) but the nut with bigger inner hole than nut used to tense the rod.


    Anyway the inner rod came out about 10mm and again the tip of the inner rod hit the inner bottom of the nut, the threads where not snapped out. When I tense the strings tha neck is again curved. Does it mean the problem on the opposite side of trust rod? The neck is 1 piece wood, so I guess the game is over now?
  12. It's a TRUSS rod.
  13. pc131


    Nov 20, 2012
    OK sorry, didn't know this word, was using tensioning rod at the beginning. TRUSS ROD since now.
  14. Andyman001

    Andyman001 Supporting Member

    Feb 11, 2010

    I can't be sure of yours, but most likely its like one of these.
    The "pipe" you referenced above is a spacer and does not go all the way through the neck. adding washers, or a nut in your case, should let you tighten more.

    when you tighten yours does it work any at all?

    is there "resistance" when you turn the nut?
  15. megafiddle


    May 25, 2011
    When you added the large hole nut, do you mean that the rod pulled out
    an additional 10mm? If you remove the large hole nut, does the rod stay
    out an additional 10mm? Or does it move back into the neck?

    If it pulled out and remained out after the nut was removed, it sounds like
    the rod is broken, unfortunately.

  16. elgecko


    Apr 30, 2007
    Anasleim, CA
    I just have to say that this problem is awesomely documented/presented. Schematic diagrams, well lit, well focused and annotated pics! Bravo!
  17. Bobster


    Mar 27, 2006
    Austin, TX
    wood at the other end of the rod could have also compressed, allowing the rod to come forward.

    Does the rod move forward more than 10mm, or does it stop at that distance?

  18. pc131


    Nov 20, 2012
    Yes when I added large hole nut, the inner part of rod pulled out additional ~10m. To be precise, it pulled out the height of the large hole nut which is working as washer, because turning the regulation nut I again reached the moment where I cannot turn the regulation nut anymore, the tip of the inner rod reached/hit inner bottom of the regulation nut.

    The nut remains in its position it does not go back into the neck.

    Anyway, thanks guys - this is an AMAZING amazing forums.
  19. pc131


    Nov 20, 2012
    This is how I like to present everything and ask for everything. Easy to read, understand and answer. Thank you.
  20. pc131


    Nov 20, 2012
    At the moment I cannot use current nut without additional washer because the inner rod (this with threads) hit the inner bottom of the nut that is used for tensing the rod. I would have to add more washers.... Anyway it looks bad. After adding this one thick washer (large nut) I was able to make many turns clockwise, there was some resistance, but like usual I think.