Allen Wrenches Don't Fit In Truss Rod?

Discussion in 'Hardware, Setup & Repair [BG]' started by Peter Rouvalis, Apr 21, 2018.

  1. Peter Rouvalis

    Peter Rouvalis

    Jan 5, 2018
    Hey, I got a Fender Mexican Jazz Bass somewhat recently and noticed it needed a truss rod adjustment, but the allen wrench that came with it wouldn't fit. I've now tried 6 or 7 allen wrenches but none will fit. Before you ask, I have adjusted a truss rod before so I know how it works. Anyone have any suggestions for me? Thanks in advance to anyone who replies. :)
  2. long shot but maybe it needs a metric key?
    gebass6, saabfender and Mvilmany like this.
  3. Pilgrim

    Pilgrim Supporting Member

    If the wrench that came with it doesn't fit,. Be careful how you proceed. Getting the right angle of attack may be difficult, and you absolutely don't want the wrench to be only partly seated into the recess.

    Try a flashlight and a probe to see if something is blocking the recess in the head. If not, try again. It's worth having a set of SAE and Metric hex wrenches around to assure you have one that fits.
    RSBBass, Haroldo and gebass6 like this.
  4. Peter Rouvalis

    Peter Rouvalis

    Jan 5, 2018
    Alright, I looked in with a flashlight and there's a bunch of gunk and dust in there, even after spending a few minutes trying to clean it out. I don't know if anything's blocking it in particular, but I'll still try to get more out tomorrow or something.

    I tried with the allen wrench again, and I think I might've got it in there? I also might've just got it stuck in there, but I'll find out soon enough. Yeah, I'll try to get some SAE and Metric hex wrenches if nothing else works. Thanks for the help, both of you. :D
  5. fhm555

    fhm555 So FOS my eyes are brown

    Feb 16, 2011
    I had an MIM i couldn’t get a wrench in and a closer look revealed there was a gob of glue in the socket.
    I dug at it for a bit with a straight dental pick and that did the trick
    Also, all my MIM basses are/were used so i never got a wrench with any of them. I later got a couple of Highway One (1) basses that included the official Fender ball end wrench and a heel adjustment but the wrench worked in my MIM head adjust truss rods.
    I keep a set of metric and standard Bondhus ball end L wrenches in my bass tool kit but i mostly use the Fender wrench. I occasionally get ropped into doing something on anther brand of bass so the L set(s) have been used, and i replace any slotted saddle screws with socket heads and have a couple of Babicz bridges so theres that, but the bulk of my truss rod adjustment work is with the official ball end T wrench.
    saabfender likes this.
  6. bigtone23


    Dec 10, 2014
    Denver, CO
    I adjust MIM with the same 3/16" T wrench used for the MIA basses as they use the same nut.
    Lownote38 and mesaplayer83 like this.
  7. gebass6

    gebass6 We're not all trying to play the same music. Supporting Member

    If it ain't standard it's metric.
    If it ain't metric.......
  8. RSBBass


    Jun 11, 2011
    If you have a glob of stuff in the slot I would be careful about what may be on the threads. It may be a good idea to take the nut off and clean the threads a put a tiny amount of lubricant on them.
  9. rojo412

    rojo412 Sit down, Danny... Supporting Member

    Feb 26, 2000
    Cleveland, OH.
    So I will say this about MIM truss nuts...

    I've worked on a LOT of the MIM basses over the years. And one thing I do when I overhaul one is to remove the truss nut and clean it thoroughly before reinstalling it with grease on the threads and possibly a washer underneath.

    If you can find the proper wrench (and it should be 3/16", but could be 5mm), you should unscrew it completely, take it out of the neck, use steel wool and/or a wire brush to remove all of the stuff that is usually attached to these (glue, polishing compound, wood, rust), then make sure the wrench hole is also clean. When reinstalling, dab some grease on the threads. Silicone grease is great, but anti-seize, lithium or any other thick grease will do.
    Hell, any lubricant is better than the none that Fender uses.

    Why do this? It will allow the truss rod to function without the binding that is associated with a filthy, ungreased nut.
    Will the truss come loose like that? No. I've done this a lot and it's never failed.
    clickclack, RSBBass and Matt Liebenau like this.
  10. A cutoff from an E string with a little hook bent on the end works nicely for cleaning gunk out of the allen head socket.
    I would avoid using ball end wrenches if you can help it; the ball end applies a lot of torque over a very small surface of the nut and can lead towards stripping. A regular allen wrench is better in this respect.
    Matt Liebenau likes this.
  11. GIBrat51

    GIBrat51 Innocent as the day is long Supporting Member

    Not much else to say, after this...:thumbsup::thumbsup:
    rojo412 likes this.
  12. mesaplayer83


    Jun 27, 2017
  13. Maybe it will add some sustain, or fix a dead spot? :woot:
    Peter Rouvalis likes this.
  14. Peter Rouvalis

    Peter Rouvalis

    Jan 5, 2018
    Thanks for all the help everybody! Sorry I didn't respond sooner, I didn't get any notifications so I doubted any one had left messages. I'll try what rojo412 suggested when I get the chance, as he seems to know what he's talking about. You're all so great! I didn't expect to get any responses at all. Thank you :)