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truss rod won't tighten any more

Discussion in 'Hardware, Setup & Repair [BG]' started by Milothicus, May 7, 2002.

  1. I have an old cheap p-bass knockoff that i want to set up to be able to play. the neck has huge amounts of relief and i want to straighten it, but the truss rod nut won't tighten any further. i pulled the nut all the way out, and it looked fine, and went back in without any problem, so i don't think there are any problems with the nut or the rod.

    the only thing i can think may be wrong, is that the nut is tightening all the way, and can't go any further. it's an allen key nut.

    what i need to know is wether or not i can add a washer or two under the nut to give it more movement. will i be doing something that will hurt the bass? i think this will fix the problem, but i don't know for sure. has anyone else tried this?
  2. pkr2


    Apr 28, 2000
    coastal N.C.
    Wont hurt a thing to add a washer or two. I've done it with good results.

    Be sure to lube the threads on the rod while the TR nut is off.

  3. i took some measurements and the nut isn't tightening all the way. it toes in about half an inch (there's about 3/4" of thread in the nut) before it starts to catch, and then it doesn't want to turn any more.

    what else would stop it from turning? it doesn't make any sense. the bass isn't worth buying a new neck, so i'm willing to try almost anything.

    could it be caught on the outside of the nut? could grease help? or would it cause it to loosen on its own? what if i put grease only on the outside of the nut?

    is the truss rod threaded all the way down? or only half an inch at the end?

    can i possibly think of any more questions?
  4. pkr2


    Apr 28, 2000
    coastal N.C.
    The truss rod is only threaded at the end.

    You could possibly have a burr on the threads or a build up of crud in the threads.

    Try lubricating the threads with something like WD40 or CRC. Run the nut down untill you meet resistance and tighten and loosen the nut repeatedly a few times. Sometimes this will straighten a burred thread and will also help to clean the threads.

    If the nut is not threading down far enough to reach the wood, you'll just have to keep working it a little at the time to free it up.

    I have seen basses that had had the truss rod tightened so many times that it actually chewed up the wood where the TR nut seats. These wood particles can gum up the threads.

    If push comes to shove, you always have the option of using enough washers on the rod to bring everything back into the adjustment range. 1/2" of thread is plenty for the nut to catch on.

    Wish I could be of more help. Just have patience and I feel sure you'll be able to fix your problem.

    Keep in mind that you are dealing with a rod that's only 3/16" so just don't get too heavy handed with it.

    Just to be sure, you can put a dab of candle wax on the bottom of the nut. Run the nut in untill you meet resistance. Remove the nut and see if the candle wax is flattened. If it is, the nut is bottoming out just as it should.

    Be sure to loosen the strings while tightening the TR so you're not fighting the string tension.

  5. loosening the strings is not a problem. the adjustment is in the heel and the body doesn't have the access groove-thing.

    i'll keep trying.
  6. pkr2


    Apr 28, 2000
    coastal N.C.
    You have my sympathy, Milothicus. That TR system can be a real bear to get right even if everything is working properly.

    I'm curious as to what brand of bass you are dealing with.

    Are you absolutely certain that the TR nut is not going in far enough to reach the wood? If you have 3/4" of thread in the nut and you can screw it in 1/2", that 1/4'' of range is very much in the ballpark.

    You might also try bending the neck in the direction of backbow by hand as you tighten the nut. Sometime that little bit of bending will make a big difference in the amount of torque needed to get the adjustment. Just put something like a book under each end of the neck and pressing down in the center of the neck makes it pretty easy to do without running out of hands.

    Since you described it as a sort of beater bass anyway, I would use the washers, if the nut is in fact not reaching the wood.

    The fact that you have to remove the neck to reach the adjustment almost ensures that the nut hasn't been cranked often enough to damage the seat.

    There is even the possibility that it has never been adjusted and the rod is siezed by the glue that holds the filler strip in the truss rod channel.

    I was adjusting the TR on a brand new bass and the nut was harder than normal to turn. All of a sudden I heard something make a cracking sound and the truss nut then loosened up enough to take another complete turn. Scared the devil out of me. I thought the truss rod had broken but it had apparently just broken the glue joint that had formed when glue squeezed out into the rout when the filler strip was glued in.

    It adjusted perfectly after that.

  7. the brand is 'profile' and the model name is 'professional'.

    It's my sister's but she never played it much. she bought it for $50 from a friend who also never played it. i think he bought it for the same price from someone else. i found it at home and took it B+). she won't mind.

    well, i know the nut's goingin far enough to reach the wood. that was just my first impression. it would turn freely until it hit something, and nothing would move it after that. that's why it was my first impression that it had been screwed on as far as it could go.

    i don't know what to do. i'm afraid to turn it any further than it goes easily. i'll get some grease tomorrow and see if i can loosen it up a bit.

    well, i just gave it a bit if WD40 and tightened it up. i think it turned about a half-turn further than it did before the WD40. i'll string it up and see what happens tomorrow. I'll keep you posted.

    thanks for all the help
  8. bizzaro


    Aug 21, 2000
    Take a good look at the threads and make sure that they are not cross treaded. Damage threads will also eventually bind and not thread after a short distance.:(
  9. no, i've determined that it's screwing in far enough. it's just that after that it doesn't want to move at all. i guess i'm just afraid to apply too much pressure. it should be lubricated and everything.

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