What a huge difference a shim makes - neck position

Discussion in 'Hardware, Setup & Repair [BG]' started by Killed_by_Death, Jan 4, 2016.


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  1. Killed_by_Death

    Killed_by_Death Snaggletooth Inactive

    I put my Fender Blacktop back together today, and left out the shim that was in there when I took it apart.
    It's just half a business card, not folded or anything.

    Anyway, when I put a string on it, it was laying flat on the fretboard at the heel.

    I took the neck off and put the shim back in, and now the action is crazy high.
    I never realized a tiny shim could make that big of a difference.
     
  2. Hmmm....Where, in the pocket, was the shim? Which end?
     
  3. sissy kathy

    sissy kathy Back to Bass-ics Gold Supporting Member

    Apr 21, 2014
    Arbutus, MD
    Yeah, it doesn't take much.
     
  4. Killed_by_Death

    Killed_by_Death Snaggletooth Inactive

    The shim was across the tops screws, if you're holding the bass upright.

    The shim is almost necessary, because w/o it the strings would be quite far from the pickups, necessitating putting some more foam under them.
    I'm also not sure if the saddles have room to raise the strings enough either.
     
  5. Precision101

    Precision101

    Sep 22, 2013
    Yeah man geometry is a hell of a important thing.
     
    Geri O and ThuzzleFump like this.
  6. Killed_by_Death

    Killed_by_Death Snaggletooth Inactive

    I was just surprised by how much it moved it. I might even look into using a thinner shim. I'll see how it goes when I start adjusting the relief and action tomorrow.
     
  7. CatSquare

    CatSquare

    Mar 7, 2014
    I made the same discovery recently messing around with shimming.

    I've tried everything and just can't tame this buzz I'm getting around the 10th fret on just the A and D strings. Messed with relief like crazy and tried a few different thicknesses of shim to achieve different neck angles, I just don't get it.
     
    Killed_by_Death likes this.
  8. Killed_by_Death

    Killed_by_Death Snaggletooth Inactive

    You should check that the frets are level, with a straightedge.
     
  9. JustForSport

    JustForSport

    Nov 17, 2011
    A .020 - .030 taper/angle from the front of the pocket to the back makes a large difference at the bridge. That's usually all that's needed regardless of which way the angle needs to be adjusted.
     
  10. Mantis Tobaggan

    Mantis Tobaggan Supporting Member

    Sep 9, 2015
    Tampa, FL
    Everytime i start tinkering with a bass i end up taking it to a tech to fix it.
     
  11. LowNloud1

    LowNloud1 Commercial User

    Jun 11, 2012
    Wilmington NC
    I am a hobbyist making stone picks that I sell but mostly give away. They made me do this anyways.
    Shims are great for improving the action on a few of my vintage basses where the actions seem to have been set higher back in their day. I used plastic because it does not compress over time like paper will and I can find just about any thickness I need around the house. Set the truss, set the shim, set the bridge and I get a nice consistently spaced action along the entire fretboard with no buzz.

    More basses now how an adjustment screw that acts as shim. My Peavey T40 has it and is something I wish more manufacturers incorporated into their necks.
     
  12. Pilgrim

    Pilgrim Supporting Member

    I've always been amazed at how much one thickness of a business card can tilt a neck.
     
    feschyn and Killed_by_Death like this.
  13. Hopkins

    Hopkins Supporting Member Commercial User

    Nov 17, 2010
    Houston Tx
    Owner/Builder @Hopkins Guitars
    I am not a fan of using shims at the front of the neck pocket. Are you sure you can't get it set up properly without it?
     
    SteveCS likes this.
  14. Killed_by_Death

    Killed_by_Death Snaggletooth Inactive

    I would have had to raise the pickups. The strings were laying flat on the fretboard, at the heel, without the shim.
    I'm not sure if the bridge would have been able to raise the strings high enough.
     
  15. rufus.K

    rufus.K

    Oct 18, 2015
    SoCal
    1/16" times 30" adds up
     
    feschyn and Killed_by_Death like this.
  16. Killed_by_Death

    Killed_by_Death Snaggletooth Inactive

    I had to lower the pickups quite a lot to get them right with the shim, so maybe I will take the shim out, and see if everything comes together.
    I only just finished setting it all up, neck relief, action, pickup height.
     
  17. JustForSport

    JustForSport

    Nov 17, 2011
    I would only change neck/pocket angle if the bridge/ saddles cannot be adjusted far enough up or down. Pickup adjustment comes after.

    If chosing to shim or taper the pocket, if it's needed in the front or the back- doesn't matter: it's what's req'd.
     
  18. rufus.K

    rufus.K

    Oct 18, 2015
    SoCal
    I bought a yard sale p bass for $13 recently. The neck was so weak and flimsy, that I had to use the truss rod to bow the neck back words a lot to withstand the string tension. So much in fact, that I had to shim the neck at the outside of the pocket bringing the nut foreword a huge amount. Thus, lowered the saddles to minimum and created a playable instrument after all the crazy geometry. Shims can save an instrument.
     
    CatSquare likes this.
  19. Killed_by_Death

    Killed_by_Death Snaggletooth Inactive

    Not sure how, but I took the shim out, screwed it back in there, and everything is just fine.
     
  20. Do the neck screws slide through the holes in the body, or do you have to 'thread' them through?
     
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