L-2500/1505 Bridge Modification

Rev 04.08.2010

This modification was done to increase the bridge to body attachment strength on my 2008 L-2500 bass.  With thru-body stringing capability, only two #8 wood screws attach the bridge to the body.  Considering that the total string tension of a 5 string bass can be upwards of 200 pounds draw on the bridge, these two small screws are pretty hard pressed to hold the bridge down.  There is no real danger of the screws breaking, but there is precedence for the screws pulling out of the wood of the body.  G&L's recommendation is to only string these basses thru-body which alleviates the issue of bridge lift, but imposes limits on string availability and makes re-stringing a bit more tedious.   This modification takes away thru-body stringing, but adds a great deal of bridge to body strength and sonic coupling.  The modification is really quite simple and is totally reversible.  Machine screws are installed in the bridge and body holes where the strings would normally go.

Parts availability may vary.  I have been able to consistently buy the necessary screws and spacers from local Ace Hardware Stores.  As of this update to the page (April 2010) it's becoming increasingly clear that there are a lot of folks from the UK and Europe reading this, but there are no Ace Hardware Stores out your way and I simply don't know where you'll be able to source these parts.  I'm confident that they are available, but I just don't know where.  As an aid to sizing and type, I have included links to McMaster-Carr, a USA-based industrial supply company.  For our friends from across the pond, these links and the products shown are for reference only, as McMaster-Carr does not ship outside of the US.

Click the images fragments below for a full view.

This is a 6-32 stainless steel machine screw.  It started out at 2" and was trimmed down to 1 9/16".  The actual length needed may vary a small amount, depending on the bass being modified.  Earlier L-2500/1505 bodies may be 1/16" to 1/8" thicker than late model basses.  Buy extra and be prepared to experiment a little.  These are available from McMaster-Carr as part number 91771A159.

This is a 6-32 threaded aluminum spacer, 1/4" long.  These have been slotted with a Dremel rotary tool
and a Carborundum disk to create a screwdriver slot.  
They are available from McMaster-Carr as part number 93330A441.

This particular example wasn't slotted very well and was relegated to backup in case I had a problem during assembly.

The screws are inserted through the bridge and the spacers are threaded onto them from the back.  I used a small dab of blue Loctite 242 threadlocker on each one so that they don't vibrate loose.

This is a view of the string ferrules on the back of the bass.  Note that the spacers, now used as cylindrical nuts, fit perfectly inside the ferrules and that the ends of the screws are essentially flush with the ends of the ferrules.

And this is the completed project.  Bridge-body coupling is so tight that the tone of the instrument was slightly altered (in a good way).  The tone of fretted notes above the 5th fret is normally somewhat muted on most basses, and this was certainly the case here until this mod was done.  These notes are now notably brighter and with a stronger fundamental.  Sustain is also greatly improved; so much so that I need to pay greater attention to muting.

Copyright 2009, 2010 Ken Baker and bassesbyleo.com