Adjusting truss rods ...

Discussion in 'Hardware, Setup & Repair [BG]' started by drumsnbass, Jan 11, 2015.

  1. drumsnbass

    drumsnbass Bassic User

    Dec 13, 2004
    Phoenix AZ area
    under tension? Some tension? or no tension from the strings?

    What say ye?
  2. sissy kathy

    sissy kathy Back to Bass-ics Gold Supporting Member

    Apr 21, 2014
    Arbutus, MD
    Opinions are all over the place. Generally it doesn't matter one way or another. Its most important to NOT force the nut, and maybe help the nut by assisting by applying a little pressure on the neck while adjusting.
    Hoochie Coochie Man likes this.
  3. Turnaround

    Turnaround Commercial User

    May 6, 2004
    Toronto Canada
    Independent Instrument Technician
    SteveCS and GKon like this.
  4. 96tbird

    96tbird PLEASE STAND BY

    I say this has been done to death.


    Use the search function to find the thread a couple of weeks ago just like this. And a couple of weeks before that and...


    I'm with Turnaround. He's a pro. Take heed.
  5. megafiddle


    May 25, 2011
    The real danger when tightening a truss rod is that the rod may be twisted along with the adjusting nut. This can occur if the threads are at the end of their length, or if the nut is not moving freely enough on the rod threads. If the rod is not under a lot of tension, this lack of adjustment freedom can be felt as a springiness in the adjustment. The adjustment nut will try to "unwind" a bit after tightening. This is a sign that the rod is twisting, and the rod has little tolerance for this type of stress. If the rod is under great tension, the friction involved can mask this springiness. Applying some backbow force on the neck can relieve the friction and make the nut easier to turn without twisting the truss rod. It can also make any springiness more apparent.

    When tightening a truss rod, the axial stress on the rod is greatest when it's in it's final position. The rod will not incur any extra axial stress in the process of pulling the neck into the proper bow. If the rod cannot pull the neck into position, it cannot hold it there either. This assumes it can do so without twisting.

    JustForSport likes this.
  6. drumsnbass

    drumsnbass Bassic User

    Dec 13, 2004
    Phoenix AZ area
    I say I'll just let Mike Lull deal with my basses.
  7. GKon

    GKon Supporting Member, Boom-Chicka-Boom

    Feb 17, 2013
    Albuquerque, NM
    Annnnnnd, my brain just exploded. :)
  8. mongo2


    Feb 17, 2008
    Da Shaw
    I say, I leave the strings at tension so I can easily check the progress. I also say always loosen the trussrod nut before tightening it to help avoid breakage.

    Forgot to say that I also say to always help the neck into position and then tighten the rod adjustment nut to hold it, never use the rod adjustment nut to move the neck.
    Last edited: Jan 13, 2015
    96tbird likes this.
  9. 96tbird

    96tbird PLEASE STAND BY

    I see.

    I say, it appears you had no intention of beginning this thread and learning anything. I say that your latest response makes it appears you started it to stir up argument and then tell us you don't even set up your own instruments, you have Mr Lull do it for you.

    Well played sir.
    JustForSport likes this.
  10. drumsnbass

    drumsnbass Bassic User

    Dec 13, 2004
    Phoenix AZ area
    I say you're wrong there.

    Back story is I have a few basses, have tried setting my own necks but never seemed to get it right. Some are over 20 yrs old now, and I fear I could break a rod because I have no idea how the metal holds up to the stresses over time. I think my latest bass may be 30 yrs old.

    So it may be better to have Mike do it than me as I'm 25 minutes away.

    And THAT was really the basis here.
  11. I've done it both with the strings tuned up, and also with them slack.

    No difference in any part of the process that I could discern, except that re-tuning after each adjustment takes significantly different amounts of time, depending on the method.

    Adjustments resulted in predictable outcomes both ways, and the effort required to turn the adjuster was the same either way, as least to my sense of feel.

    All the best,

  12. marko138


    May 24, 2013
    Perry County PA
    Tuned to pitch is how I do it. Help the neck get to where I want it, turn the rod. Re-tune.
    tangentmusic and JustForSport like this.
  13. JustForSport


    Nov 17, 2011
    The metal has no problem 'over time'.
    However, keeping up with changes in the neck wood over time could bring its adjustment range to the end of its avail travel,
    and if the bass (not yours, of course) has been sitting or neglected for awhile and there is quite a bit of bow-
    that skinny rod (probably not lubed at the threads) may or may not be up to the job of bending the neck straight against the tension of the strings AND the memory of the neck.
    Best to 'help' it, in that case, IMO.
    No reason to take the risk if it's preventable (IMO).
  14. tangentmusic

    tangentmusic A figment of our exaggeration

    Aug 17, 2007
    This is a big 10-4
  15. 96tbird

    96tbird PLEASE STAND BY

    Noted. The back story clears up the confusion.

    By your post about Lull, it seemed as if you were saying you had always been taking them to him.
  16. drumsnbass

    drumsnbass Bassic User

    Dec 13, 2004
    Phoenix AZ area
    I have been, and was seriously contemplating doing my own attempts at a real setup.

    However my latest purchase is like a 30 yr old Pedulla, and maybe I'm just being a worry wart, but I fear a rod breaking on me if I overdo it somehow. What I prolly need is some POS bass to practice on a bit first. I have lightly adjusted another Pedulla I own, but that was ever so slightly and nowhere near as old.

    It was mentioned above the metal should handle it, and I agree that it 'should', but then you see the occasional post of a rod head breaking off, or a rod itself breaking, and I just get nervous about it all given the age involved.

    Plus I don't really have the 'feel' to know if, should there be an issue, I am twisting the rod v. it turning freely.

    So originally I thought no tension. Then I thought, well I did my Hexabuzz under tension, so maybe under tension (new bass is a bit bowed), and then I had bad visions and said maybe you all can enlighten me. And finally said let a pro do it the first time to make sure I dont f it up.
  17. drumsnbass

    drumsnbass Bassic User

    Dec 13, 2004
    Phoenix AZ area
    Btw, the new 30 yr old Pentabuzz is like two bumps from being new. Real closet queen. A joy to behold!
  18. JustForSport


    Nov 17, 2011
    If the 'new' bass is bowed, detune a full tone or more before tightening the trussrod:
    the trussrod counters the string tension, and if it is in tune, then tightening the trussrod will have to stretch the strings sharp (higher tension) than normal, or compress wood (depending on trussrod type) to get the bow out. Lesser string tension will not harm anything and it'll make it easier to 'help' the neck into straight, then using the trussrod to hold that position.
    Anyone that wants to just torque the rod 'til the bow is out, with the strings at tension is not paying for the consequences of any damage that may be done- let them say what they want. (And do a little search here about replacing a damaged or broken trussrod on one of those).
  19. drumsnbass

    drumsnbass Bassic User

    Dec 13, 2004
    Phoenix AZ area
    It's stuff like this /\ I don't necessarily think about.

  20. 96tbird

    96tbird PLEASE STAND BY

    Well I can see your fear. When I bought my 1962 jazz I could tell by the virgin condition of the slots in the nut that it was unlikely that it had ever been adjusted. For its 50 years, it wore nylon tapes. Looked too flat, but played great. Once I put some Sunbeams on they buzzed on the first fret and open. I slid my driver in and loosened it a 1/4 turn and she relaxed into perfect relief.

    Of course I was gentle. I have a rule. I always loosen first. Then if I need to tighten I turn it back the same distance to feel how the threads feel and how the rod responds. Then I carry on tightening. I only use my thumb and two fingers to grip the driver. This gives you a good sense if the rod is torquing (bad) it if the nut is moving (good). When I tighten I pull my neck flat with my hands and move the nut into position to hold, I don't let the nut do the flexing.

    Rods on the whole are quite sturdy if you just proceed with gentle hands... Like working on the engine of my 1973 Honda. Two finger tightening or you'll strip that aluminum thread.
    Last edited: Jan 14, 2015