Shimming the neck; pros, cons?

Discussion in 'Hardware, Setup & Repair [BG]' started by parrott, Oct 13, 2003.

  1. My new 6 has a scarily high action (according to me, my DB-playing teacher loves it). The instrument technician at college recommend shimming the neck rather than just lowering the bridge saddles - I trust him, he made my Epi EB3 into a nice, playable bass - but what are the pros and cons of doing this?

    I know what it involves, but how does it compare to lowering the bridge saddles, or any other action-lowering operation?

    ps. first post tince August...... kinda scary to be back
  2. There's no sweat with the shims. Lotsa bolt-ons have 'em and plenty more probably need 'em! It's a pretty common part of a decent tune-up but only when needed. If your neck is adjusted for proper relief AND you've lowered your saddles as far as is practical THEN you'e a candidate for shimming. The idea of a shim is to compensate for the neck pocket being routed to close to parallel with the face of the body. A shim will usually be used to raise the heel of the neck ever so slightly. The fulcrum for this pivoting is the First pair of neck bolts. A small strip of veneer or a business card - anything the right thickness can be used between the body and neck. This small dimension is magnified by the off-center location of the fulcrum to make a substantial pitch difference at the headstock.

    The first new Fender I ever bought had one from the factory. I just put a substantial one in my latest build. In that last case, it's too much of a crutch for bad machining and I'll rerout the neck pocket to fix it. But go for it. You'll be surprised at the difference one can make.
  3. embellisher

    embellisher Holy Ghost filled Bass Player Staff Member Supporting Member

    As Hambone stated, neck shimming is a perfectly acceptable solution for bolt on necks that can't be adjusted low enough for your playing needs, as long as the shim is done properly.

    My Zon Sonus Custom fretless 5 has a shim. I put it there myself, because I couldn't adjust the bridge saddles low enough for my liking, and since the neck has no truss rod, there was no other way to lower the action.
  4. JMX

    JMX Vorsprung durch Technik

    Sep 4, 2000
    Cologne, Germany
    You only need to shim when you've found that the saddles don't go low enough.

    Shimming is the last resort.
  5. metron

    metron Fluffy does not agree

    Sep 12, 2003
    Lakewood Colorado
  6. Well, I've had it done, and I'm very pleased with the result - much nicer to play, faster, etc.

    The tech. gave two reasons for shimming it rather than adjusting the bridge saddles so low. The first is so the distance between the strings and the pickups stays the same, which I suppose is fair enough if you've spent a time setting them so they're 'just right'. The second was so you didn't have the little screw bits of the saddles (I don't know the name) too proud os the saddles themselves. The way I look at that is, when I'm playing with a pick, or generally strumming, if the little bits are too proud of the bridge saddles, they'll scratch your hand a lot.

  7. poppamies


    Dec 15, 2002
    One advantage of shimming is that you can maintaine the string angle at the bridge, or even increase it, and that's also good for body coupling. One other thing is you can avoid to have the strings to near the pickups and don't get the infearence from the magnets. The only probable disadvantage could be loose fiting or bad coupling between the neck and body if done poorly.
  8. Tim Cole

    Tim Cole

    Jun 12, 2002
    Findlay, Ohio
    Most all basses (including my 535) end up with a shim adjustment to get it to my liking.
  9. Umm, I don't know a lot about exactly how to shim a neck but won't it mean that you'll change the contact between the neck and the body? This would then affect your tone wouldn't it? Or do you angle the shim itself so that its as close as you can to a perfect fit? Cause I'm thinking that'd be pretty darn hard to do.

    Josh D
  10. poppamies


    Dec 15, 2002
    Teoretically yes and yes. In practice no and no.
    Teoretically the coupling ain't as good as without a shim and one could imagine it will affect the tone. But in real life nobody will notice the difference.
    There's also really no need to taper the shim for any other reason but for peace of mind even if it can be done fairly easy by glueing the shim temporarly to a suitable surface with a couple of drops of super glue and using a sanding block.
  11. Stu L.

    Stu L. Supporting Member

    Nov 27, 2001
    Corsicana, Texas
    Hambone, should the 2nd pair of screws pierce the shim? Should it be that large? And would business cards or anything else of a rather thin nature need to be stacked?
  12. Stu L.

    Stu L. Supporting Member

    Nov 27, 2001
    Corsicana, Texas
    Well, I gave up and tried it. Stacked 2 business cards, re-assembled, and it looked great. Took the saddles up, but they couldn't go high enough. So, back to one card with the re-assemble, and perfect.

    It amazes me that one business card made that much difference.
  13. Wilbyman


    Sep 10, 2003
    Parkersburg, WV
    Anybody notice a loss of tone with a shim? I put a business card shim (I think I tried one or two stacked) in my Fernandes jazz's pocket and noticed a substantial loss of sounds in the lower-midrange. I'm beginning to think I'm becoming Eric Johnson, who is super sensitive to tone changes from things like different batteries in his pedals and different screws in his cabinets!

  14. I have to say, I haven't noticed any kind of effect to the tone from the shim.

  15. Stu L.

    Stu L. Supporting Member

    Nov 27, 2001
    Corsicana, Texas
    Neither have I.
  16. Billdog


    Feb 27, 2003
    Austin, Texas
    Actually, I've read several repair and adjustment books, and they all say shimming isn't just a last resort. Setting the proper neck angle does not just help the overall action, if it's incorrect you will have action balance problems, i.e. too high on the upper frets and too low on the lower frets necessitating shimming, or vice versa, necessitating a removal of shims. While this can be fixed by a change to the nut, you may mess with your intonation if you do that. Instrument adjustment is much more complex than raising or lowering the action. All of your possible adjustments should be balanced.
  17. I did! I noticed a loss of sustain and idk a loss of growl I suppose.
  18. jani_bjorklund


    May 22, 2002
    Many basses, even custom made axes come with shimmed necks. The shimming is done to make the bass better to play and practically don't have any effect on the sound.
  19. FWIW, I had the tech. shim the neck on my main bass (my Aria fretless 5, I didn't trust myself to do it at home, and anyway, he was setting the intonation, way above me, especially on a fretless). Anyway, he did that, and with just a piece of carboard in there, it's made such a difference, it's like a different bass, playing wise.


    Maybe it's because basses tend to come with a high action, while I like as low an action as I can get away with - *shrugs*
  20. None of the discussion about tone changes after shimming has mentioned the possibility that a different shim material would be more suitable than another. That's where you can make changes too.

    Paper, while wood in a sense, is soft and probably isn't a great coupler for tone. You could try other materials like aluminum tape, acetate, thin aluminum shim stock, brass shim stock, wood, or other harder material or one that is more similiar to the wood of the bass. If you can hear a difference between a shimmed neck and an unshimmed neck, you should have no problem discerning the better of 2 or more shim materials.