4 String to 5 String bass conversions

I am a long time 4 string Rickenbacker player. Then I got into bands where I needed notes lower than the low E. So I would play my 4 string Rickenbacker for most of the songs and a 4 string jazz bass tuned DGCF for the other songs. But then I needed a low D flat so I switched to a 5 string bass. My first 5 string was a Rickenbacker 4003s5.

But the Rickenbacker 4003s5 is hard to play fingerstyle because of a 2 1/16" spacing at the bridge. So I started modifying 4003s5 basses so they had a string spacing of 2 1/4 or 2 3/8" which makes them easier to play. About 2001 Rickenbacker quit making the 4003s5 basses so I started modifying 4 string basses into 5 string basses. I have sold off most of my Rickenbackers and now mainly play my Fender style basses that I have converted into 5 string basses.

Here are some of my conversions.

Home

The steps I use for converting a 4003 4 string to a 4003 5 string.

1st ... I remove the tuners and drill one extra tuner hole in the headstock, then I install Schaller or Gotoh sealed slimline tuners.
 
2nd ... I get a 6 string preslotted nut from Carvin and I grind it down to 5 string size and install it.
 
3rd ... I take the 4 pole high gain pickups and remove the 2 middle poles and drill 3 holes and put in 3 iron slugs, so it has 5 pole pieces.
 
4th ... I either modify a Ric tailpiece or allparts tailpiece or use a 4003s5 tailpiece. Then I install a custom made stainless steel bridge. I cut the grooves on the saddles to 2 1/4" spacing.
 
then I string it up and do a set up and play it ... the modern 4 string 4003 takes the low b string quite nicely ... the neck has plenty strength and the extra string actually improves the resonance of the 4003 ... sort of like putting round wound strings on the old 60's and 70's Ric basses brought them alive and the additional tension on the neck changed the resonance of the bass ...

For my Fender style basses that I convert in 5 string basses.

I like to start with a p-bass 4 string neck. I replace the nut with a blank that I put 5 slots in. I add a 5th tuner and a string tree.

I like to use Schaller 5 string bridges. Also 8 pole 4 string pickups wrok just fine for 5 string basses as long as you don't make the strings wider than the pickups.