Strange neck problem.

grobe · #1 05-13-2011, 02:04 PM

I recently removed my neck on my MIM 60's jazz bass because I was having problems tightening my truss rod. So I removed it and made an adjustment, but after I screwed the neck back onto the body I'm finding that I have to raise the string height almost all the way up just to get the lower 6 frets to stop buzzing. There seems to be some slight relief (like there should be) so I'm not sure why I needed to adjust the string height so drastically. I always do my own setups, and I have that part mastered.

Did I re-install the neck wrong?? What could causing this problem?? I would like to avoid taking the bass to a shop obviously.

JLS · #2 05-13-2011, 02:19 PM

Sounds like it needs a little more relief. You do mean the frets closest to the headstock by, "lower", correct?

Bassics101 · #3 05-13-2011, 02:29 PM

If the neck hasn't really been changed too much by your tightening the truss rod, it sounds like there might be something keeping the neck from seating all the way to the body. That could be angle the neck upwards at the body. Something under the neck, some sawdust etc that is keeping the neck from tightening down all the way? Or was there a shim of any sort that could have moved?

Also, when tightening the neck I always use a cross pattern and tighten the screws in several steps so that it is never pulled too much by the front or back screws.

Just some quick thoughts.

darkstorm · #4 05-13-2011, 03:28 PM

Did a shim fall out when you took the neck off? That would certainly explain it. Prob needs a shim reinstalled.

grobe · #5 05-13-2011, 03:38 PM

Quote:

Originally Posted by JLS

Sounds like it needs a little more relief. You do mean the frets closest to the headstock by, "lower", correct?

Sorry, should have said upper. Frets 15 to 20.

grobe · #6 05-13-2011, 03:39 PM

Quote:

Originally Posted by darkstorm

Did a shim fall out when you took the neck off? That would certainly explain it. Prob needs a shim reinstalled.

No, I didn't think a shim was in there to begin with. That would definitely explain the problem, huh? Hmmmm.

Quote:

it sounds like there might be something keeping the neck from seating all the way to the body.

This might be it. The relief actually looks ok. I'll try to re-seat the neck to be sure. Any tips on how do this? I might have rushed it.

Thanks for the help everybody.

Bassics101 · #7 05-14-2011, 06:48 AM

For me, kinda like putting a tire on a car, or other such thing. Put the screws in, tighten them loosely, then go from corner to corner (like an X) tightening them a bit at a time until you are done. And don't over-tighten. It's wood and can strip. Firm, but not aggressive.

john grey · #8 05-14-2011, 10:12 AM

Tighten the neck and it gains a flat plane relief (tightening it is CLOCK-WISE) Loosening the Truss-Rod (COUNTER CLOCK-WISE) will allow flex.

This is generally done with the neck in position and in many cases with string tension. It is also very important to do this at a 1/4 turn at a time (DON'T crank it; work in increments slowly and allow it to settle). Excessive Truss-Rod turning can result in problems. The work should be done in increments, slowly, and allowing for the neck to adjust in position. Remember his is a laminated unit under tension, etc. It's really never a good idea to turn 1/2 rotation at an adjustment sitting; this is very standard with virtually every major manufacturer.
Some fellows use 1/6th turn and wait well over an hour before turning again; some even wait over night or play on the guitar for extended periods. The point is that it needs to adjust.

There IS a possibility that the neck was shimmed. The best method is with manufactured shims (which are often metal and stamped with size #). However occasionally it's done with paper, cardboard, etc which has a tendency to "settle" or fall out unnoticed. Additionally there are necks that need to be in exact position and improper re-setting of the neck can slip over a wooden "thread" of the wood-screws especially if a power screwdriver is used (always use a hand-screwdriver).
A very important point here is that the wood used in a neck is almost always harder than that of the body. Therefore if the neck junction is not level flat (difficult to achieve is mass production occasionally) then the wood will press an impression that can be distorted if not placed back EXACTLY as it was set! Problems arising can be "appearing as warped", fret buzzing, and intonation issues.

Over tightening can lead to all sorts of problems; including what you are describing. It can also crack the finish or worse. The compression can certainly alter the mating of the neck & body. Replacement of the neck should be done very carefully with a hand screwdriver. The neck WILL be set strongly with hand torqued pressure. It should not be "cranked".
Back it out of there. Check for any evidence of a shim. Replace if necessary. Replace the neck with a hand screwdriver. Torque should be approx. 5-12lbs depending on depth & screw thread, string set / number, and width.

JLS · #9 05-15-2011, 12:18 PM

Quote:

Originally Posted by grobe

Sorry, should have said upper. Frets 15 to 20.

Ski jump. Trussrod won't fix it.

If you were tightening the trussrod, that leads me to assume that you had too much bow in the neck; by tightening it, and straightening the neck, you effectively brought the action down, into the zone where the ski jump became an issue.