Please help: Fender J Bass Plus - odd size truss rod nut!

AlexanderB · #1 03-31-2011, 03:34 PM

I just bought a 1994 Fender Jazz Bass Plus V which turned out to have a cracked truss rod nut. Threads are OK but the Allen key grip was split open by wrong size tool or too much force. I (eventually) managed to remove the split nut and clean the headstock channel. The nut is cylindrical, not bullet style.

Then I realize that the nut is not a regular size. All information I have found indicates that Fender have either a 8-32 or 10-32 thread (and some models have metric threads).
For starters, it is not metric. M5 is too small and M6 is too big to fit the threads. However, the truss rod thread is larger than 10-32. It seems like it could be a #12 thread.

There is a "super size" Fender truss rod nut that is called 003-8443-000 but the only information I have found so far is that the Allen key fitting is size 5/16" in stead of the regular 3/16".
Can anyone confirm if that is the right part for this bass? Or perhaps if the thread is actually bigger than 10-32 on that nut.

Any help is much appreciated.

edit:
By the way, I have called five MI shops (not small ones) and nobody had even a regular truss nut rod on stock. No wonder customer prefer shopping online...

walterw · #2 03-31-2011, 07:39 PM

this is a USA bass? if so, it should be a 3/16" hex hole, and the larger non-metric thread size.

(edit: i just looked at online shots of one. try a mexican standard truss rod nut, which has the 3/16" hex hole, but is physically skinnier than the normal modern USA nuts. the mexis go in the headstock while the modern USA versions go in the heel end of the neck.)

AlexanderB · #3 04-01-2011, 01:42 AM

Thank you for the reply.
The bass is indeed made in US. The nut goes in the headstock. If you look at the part 003-8443-000 at Fender.com, the hex hole is specified to be 5/16". The thread size is however not listed. My concern at this point is that I have never seen any truss rod nut with a #12 thread like this bass seems to have.

/Alexander

Dieter · #4 05-03-2011, 04:05 PM

Hey,

I'd be interested to hear how this works out for you as I am having the exact same problem with a 1992 Jazz Plus V. I was able to back the truss nut out, but need to find the correct replacement.

10-32 appears to be correct though for the threads, and 5/16" seems way to big to me for the allen key. I think it should be 3/16" though I needed to use a larger one to back the sucker out of there.

Keep us posted on how things go.

fhm555 · #5 05-04-2011, 08:00 PM

Don't know if the 4 and 5 are the same, but my US jazz plus IV requires a 3/16 allen for truss rod adjustment.

As for what pitch the nut threads are, if you have the nut and threads are still good, take it down to your local purveyor of threaded products and try bolts until you find one which correctly fits the threads in the nut. You will then know what your truss rod thread size/pitch is. An alternative is take the nut by a good machine shop and see if they will put a thread gauge on it for you. Hope this helps.

AlexanderB · #6 05-12-2011, 07:51 AM

I "solved" the problem by welding a regular Allen key screw to the original truss rod nut. After cleaning up the welded joint, the new "composite" screw went straight back in the neck - no problem. I will however still order the genuine sparepart (with a 2 month lead time - minimum) for future work.

Dieter · #7 05-26-2011, 11:06 PM

What is the correct replacement part then? Where did you source it? I have tried the Am. Standard nut ("for standard and plus instruments") as well as the mexi nut, both no good!

I guess I'll just see a machinist then.

By the way, I tried calling Fender. Total waste of time! Seemed they thought the best idea was to buy a whole new neck instead of a $6 nut! Turns me off from buying new Fender instruments. Not that their used stock doesn't interest me...