Truss rod nut has seized

Discussion in 'Hardware, Setup & Repair [BG]' started by IsleyBros, Aug 23, 2017.

  1. IsleyBros


    Jun 10, 2016
    The truss rod nut is completely seized on a Yamaha BB414 that i acquired recently. It's a regular hex nut placed at the heel.
    Took the neck off completely and clamped it into a back bow BUT even then to my shock the nut would still not give one bit in either direction.

    I tried to spray some anti rust into that little hole in the nut, left it upside down and waited a day but still nothing. I don't even know if it has rusted but that was the only reason i could see why it would be stuck. I have yet to try some penetrating oil.

    Anybody had a similar issue that they managed to fix or do i just have to live with not being able to adjust it? Please no "take it to a luthier" talk, don't bother.
  2. Bruce Johnson

    Bruce Johnson Gold Supporting Member Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Well, if it's seized, it's seized, regardless of how or why it happened. If it's all original parts, then it's probably corroded. A drop of good penetrating oil like Kroil is your best bet. But you're going to have to mechanically break it loose somehow. With some risk of damage, like rounding off the nut, stripping the threads, or snapping the rod. No easy happy answer here.

    One thing that might help: Have you seen these small cordless electric impact drivers that are used for driving drywall screws? Most carpenters/contractors have them these days. The vibrating impact drive might break the threads loose without harming anything. Couple up a good hex socket to fit well on the nut, and one of those square-to-hex adapter bits to fit the electric driver.
  3. Oren Hudson

    Oren Hudson

    Dec 25, 2007
    Gastonia, NC
    As BJ mentioned, Kroil will loosen just about anything like that. I first discovered it when trying to remove rusted stuck spark plugs on a car. Heat will also probably help. Use a hair dryer to head the area real good. That should help. If it's still stuck, I'm out of suggestions. o_O
  4. If you decide to try heat another option would be a soldering iron or gun if you have one that will reach the nut without burning the wood around it.
  5. Coolhandjjl


    Oct 13, 2010
    I'm sure you tried this, but sometimes tightening first can help to break it free.
  6. zortation


    Dec 26, 2011
    Toronto, ON
    Coping saw.

    If enough of the nut is showing, cut a small notch across the centre at the top of the nut with a coping saw, then grab a slotted screwdriver and try to unscrew the nut. There's a 75% chance it'll work....or thereabouts.
  7. GIBrat51

    GIBrat51 Innocent as the day is long Supporting Member

    I would go with Bruce's suggestion, but I would apply some heat first, before using the Kroil (which I have had great success with, too). A little heat seems to make it penetrate better - for me, anyway... Sticking the whole neck in a freezer - if possible - until it's good and cold; then applying some quick heat on just the nut itself, before trying to loosen it, might do the trick, too...:thumbsup:
    Last edited: Aug 30, 2017
  8. LEH - Ellis

    LEH - Ellis Commercial User

    Aug 21, 2017
    Portland Oregon
    I am the founder of LEH Guitars
    I agree with the penetrating oil suggestions. When I was restoring my motorcycle that oil saved me more than a couple times. If the hot/cold combo doesn't do the trick... another thing that helped was giving it a good smack with a mallet. Be careful of course, but install the truss rod tool, and then whack the tool with a mallet. Sometimes rust just needs a little encouragement/threat to let go. You'd be surprised the amount of things that can be fixed with a mallet.
    Gully Foyle likes this.
  9. onefitter


    Apr 14, 2017
    Try penetrating oil and an impact driver.
  10. Turnaround

    Turnaround Commercial User

    May 6, 2004
    Toronto Canada
    Independent Instrument Technician
    I'd follow the advice from Bruce Johnson. If you don't have access to an impact driver, put a hex key in there and give the key a sharp whack with a lightweight hammer. - you don't want to beat it to death, it's the sudden impact that does the trick. About this much force |-----------------| (um.... I don't know how to describe the right amount of force - maybe just enough to crack a walnut - crack it, not smash it). But only after fist applying Kroil and letting it sit for a while.
    Lownote38 likes this.
  11. IsleyBros


    Jun 10, 2016
    Ordered some high quality penetrating oil. I'll have see how that works before trying heat or whacking the nut
  12. Lownote38


    Aug 8, 2013
    Nashville, TN
    I've had great luck just tapping the hex key with a hammer while it's engaged in the truss rod nut. That usually gets it freed up even without the oil.
  13. IsleyBros


    Jun 10, 2016
    Tried penetrating oil, soldering iron to the nut, whacking the hex key with a hammer but nothing worked. I guess the neck is a bust
  14. IsleyBros


    Jun 10, 2016
    Update: Ha, i finally managed to get the nut off. I think the penetrating oil helped a little bit but ultimately had to use brute force to get it off because at that point i did not care if i broke the rod or not.
    It was all corroded
  15. hotbass57


    Nov 27, 2011
    So the truss rod was still intact after that? Good luck with the truss rod and hopefully it will set up for you.
  16. IsleyBros


    Jun 10, 2016
    Yes i think so. I cleaned the threads up as best as i could and lubricated. It creaks like hell when i tighten the nut.. with or without washers. It's from the friction of the nut digging into the steel, i'll have to try a brass washer at some point because i've heard that creates less friction than steel against steel.
  17. Callused Finger

    Callused Finger

    Feb 22, 2007
    New York
    Replaced the nut?
  18. IsleyBros


    Jun 10, 2016
    Not yet but i probably should