Here's a demonstration of how to replace the neck on your Fender Jazz Bass, or non-Fender Jazz style bass.
Things you'll need:
Replacement Neck (and Neck Screws)
Tuners (and Tuner Screws and Trim Pieces)
Drill Press and Appropriate Bits (Depending on Screw Sizes)
Bench Vice (Optional, But Helpful)
If you don't have access to a Bench Vice, you could likely use a hammer and some scraps of wood to protect the neck and the hardware.
Step 1: Remove Old Neck (Pocket Preparation)
We used a cheap Non-Fender bass, so we had to smooth out the pocket. If you have a Fender or a Squier Bass, the pocket should be ready for a new neck already. We used a Mighty Mite neck (model MM2909), which I would recommend. It required no fretwork, and plays very comfortably.
If you have a Fender or Squier, I would recommend buying a neck licensed by Fender, or at least one that was designed for a Fender. It's no bad thing if you want to, but you don't want to have to work on the pocket because of a mis-matched neck.
Step 2: Drilling Holes (Preparing the Neck)
Next, you have to drill all the necessary holes in the neck before installation.
One good way to mark the holes is to superimpose the patterns from the body and your tuners onto the neck. As you can see in the pictures, we used a square against the top of the headstock to make sure the tuners were perpendicular to the top edge. For the neck joint pilot holes, we put the neck into the body, and used the holes through the back of the cavity to mark the back of the neck. When doing so, just make sure you get the neck to sit in the pocket all the way towards the bridge, and all the way down flush against the flat bottom. For marking the hole for the string tree, we just measured the placement of the original, and tried to duplicate that on the new neck. This is generally not a good thing to do, but this is not structural, and thus doesn't have to be as precise as the other holes.
When drilling, make sure you set a maximum depth on the drill press based on how long your screws are. For your drill bit size, you'll want to use a bit that is the same size as the shaft of your screw, and not one that reaches to the extent of the threads. If you're unsure, it is best to start a little small. You can't add wood back! For hole depth, you'll want to stop where the screw stops, or just a hair shorter.
After all, you don't want to go all the way through!
Step 3: Install the Hardware
We used all the hardware that came off of the old neck, including the tuners, trim pieces, and the string tree. We did get new screws, but that was only because the old ones were rusted.
To get the trim pieces into the tuner holes, which should already be drilled from the factory, we just used a bench vice to press them in. When doing so, you'll want to use a softwood scrap against the neck to keep it clean, and un-dented. We used a piece of metal roof trim against the trim pieces.
Once those are all in, you can go ahead and screw the tuners and the string tree on.
Step 4: Put It All Together (Installing the Neck)
At this point, all that's left is to screw the neck on, and to put on your strings. We used Curt Mangan round-wound strings, gauges 45-105.
You'll likely need to adjust the truss rod, and your intonation (the height of the bridge saddles, etc.)
This is a normality, so don't be daunted by it. We cranked the truss rod roughly a turn and a half. However, it would be wise not to crank it too much initially. As the neck gets used to all that tension from the strings, it may bow out. If you tighten the rod too much, it may back-bow, and you don't want the wood to get used to that.
If you really want the bass to feel and sound the best, it is always wise to take it to a professional instrument repairman to get the intonation set up right. Having the action how you want it and the intonation accurate will make you feel good about your sound and your playing.
After all, you want to enjoy playing!
Be sure to check out our Demo of this bass, which I have embedded. There, you can see additional pictures of the process of putting on the neck, as well as some video of the drilling process. Thank you to all who check it out!
Don't be afraid to watch some of our music too!
The channel is called "the Arkwright Loft":