1995 Rickenbacker 4003s/8 Structural Repair

In December 2012, I purchased a Rickenbacker 4003s/8 8-string bass project from Ishibashi Music in Japan.  The bass had been heavily discounted due to a structural issue that had rendered it unplayable.  If I recall correctly, their website listing stated something to the effect of: “major faulting, we do not recommend this bass” :)

I had some idea of the issue, but wasn’t entirely sure what to expect… or whether I could even repair it.

 

Similar to the standard 4-string 4003 series of the era, these 8-stringers were also of a neck-through-body construction.  I’ve corresponded with a number of owners over the years, and have gotten the impression that there are two types of 4003s/8s and 4008s in the world:  a majority without any problems, and a handful that have developed structural issues – typically neck and body de-laminations (like this bass) or warped necks, possibly due to truss rods and/or wood that just didn’t cope well with the tension of the additional strings.

At some point in the life of this particular bass, the neck had snapped free from the body as it began folding in:

 

The cracks along the neck and body seams extended roughly 5cm into the body on the bass side, and 4cm on the treble side.  This area butts right up against a long, narrow pole-piece route, as seen in the photo below.

That is the deepest part of the neck pickup’s swimming pool, and leaves only 1cm of wood remaining in the neck structure:

 

This seemed to be the place where the bass wanted to cave in on itself when under string tension, and my thought was to attempt to reinforce this entire area in an effort to stabilize it. The Rickenbacker Resource Forum had some posts depicting one builder’s solution for this problem – which involved filling the swimming pool with a maple insert, and making a more economical and deliberate route for the pickup and truss rod channels.

This seemed like a sound approach.  After-all, the pickup really doesn’t demand much space, and that deep pole-piece cavity could stand to be roughly 6mm more shallow (and quite a bit narrower):

 

Well, if there was any good news in all of this it would be that the bass is simply stunning! The flame and birdseye figuring in the wings is gorgeous, and it looks to have hardly been used.

 

 

After acquiring some maple for the repair, I traced patterns for the insert pieces needed to fill the neck pickup route.  I began by making a more exacting route for the toaster pickup:

 

I wanted to leave as much structure there as possible to reinforce the neck; therefore, I used the drill press to make way for the pole pieces – only removing a minimal amount of wood:

 

I then cut out the maple grafts using a scroll saw, and got the rough shaping done:

 

I built a makeshift “torture rack” to stretch the neck back into its original position :)

 

Using a couple of ratcheting nylon tie-down straps around the workbench, I anchored the body firmly to the table.  A 1″-diameter PVC pipe (left over from working on my lawn drip system) was gorilla-taped to the table and served as a fulcrum point, and towels kept it covered so as not to mar the body.  I then tightened the headstock strap until the neck angle sat just slightly beyond the desired resting position.  The plan was to complete the final shaping of the reinforcement pieces by hand and get the fit nice and snug, route channels for the truss rods, glue the reinforcements in, and then release tension on the headstock strap so that everything snugs up and the neck and wings align evenly.

As for the body wing de-lamination, my thought was to drill a couple of tiny pilot holes into the seam and use a syringe to inject glue.  Obviously, the most reliable solution would be to completely remove and re-glue/clamp the wings; however, I really wanted to avoid having to refinish the bass if possible.  The mechanical fit between the wings and neck seemed sound, and upon recommendation from some others more experienced in these types of repairs I opted to try an approach of using thin CA glue to secure the wings.

All existing varnish was stripped out of the pickup cavity…

 

Once the swimming pool plug was shaped, I ground some channels to facilitate truss rod nut access at the body end and test-fitted the toaster pickup:

 

In prep for installation of the swimming-pool graft, I drilled some pilot holes and injected thin CA glue into the broken body-wing seams:

 

I then installed the graft using Titebond, and also attempted to finish it using some leftover cherry, amber, and clear lacquer that I had on-hand.  Easier said than done!  (At least its hidden under the pickguard :)

 

While the glue was drying, I applied a slight amount of tension between the neck and graft using a tie-down strap:

 

Here it is amidst reassembly:

 

…and back in action!

 

 

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