Fender truss rod issue - wood compression?

ToneRanger · #1 12-02-2007, 12:31 AM

I recently converted my 80's Kinman Jazz fretless to fretted by replacing the neck wirh a new Jap Fender Jazz neck (62 reissue). It all went together well and sounds wonderful. The New Guinea Walnut body gives a brighter, more defined sound than a Fender.

However I can't get the neck to sit straight. I've now tightened the truss rod 6 times; each time I removed the neck completely, clamped it with some reverse bend, and adjusted as far as I felt was safe. When I restring the neck it's almost dead straight, but overnight it settles back into having too much relief. Each time I do the adjustment there's an easy half turn before it starts to feel tight. The truss rod nut has been working it's way into the socket - it's now recessed about 5mm. All this indicates to me that the wood is compressing under the adjustment nut.

At the moment it's playable, with about 2-3 mm of relief, but my other bass is a Warwick Thumb with an absolutely perfect thru-neck; I don't expect a vintage-style Fender neck to ever be that accurate, but I'd really like it to be a lot more playable than it is now.

I've asked a couple of repair guys, and searched online - the only suggestion I've had is to add some spacing washers under the nut, but that doesn't seem to fix the underlying problem. I'm concerned that I might be damaging the wood at both ends of the rod.

Anyone had a similar issue? Any suggestions? (other than buying a better neck - yes, I now realise I should have bought a Warmoth!)

lowendgenerator · #2 12-02-2007, 01:40 AM

Well, if you pull the rod straight through both ends of the wood, the neck is ******. I don't thinks that's the case though. Are you using strings with ridiculous tension ie; Fender 9050 flats? Might the neck pocket need shimming? Spacing washers usually fix the problem, sometimes the neck just needs to be adjusted a little outside the scope of normal truss rod adjusting.

ToneRanger · #3 12-02-2007, 04:42 AM

Quote:

Originally Posted by lowendgenerator

Well, if you pull the rod straight through both ends of the wood, the neck is ******. I don't thinks that's the case though. Are you using strings with ridiculous tension ie; Fender 9050 flats? Might the neck pocket need shimming? Spacing washers usually fix the problem, sometimes the neck just needs to be adjusted a little outside the scope of normal truss rod adjusting.

Strings are just D'Addario 45-105 - not high tension; neck angle is OK, it's the curve I'm trying to get rid of. I'll try some washers and give it another tweak...

ehque · #4 12-02-2007, 07:31 AM

Keep going at it. Most probably the wood is not compressing, it is the neck angle changing so the distance covered by the truss also has to change.

Adding washers only works when you've run out of truss rod nut adjustment space. IF i remember correctly it doesn't do anything if you're not already maxing out your adjustment.

62bass · #5 12-02-2007, 01:59 PM

[quote=ehque;4976735]Keep going at it. Most probably the wood is not compressing, it is the neck angle changing so the distance covered by the truss also has to change.

It might not do anything unless you run out of thread, but he soon will if he has to turn that many times. It does seem like there could be a problem with the truss rod and maybe there is some sloppy work done that's causing the wood to compress. Washers might help that. I'd get some and keep them handy just in case. In fact, I'd probably put a couple on and see if that is the problem-wood compressing under the nut. If the washers have a bit more surface area than the nut it might help.

Jim Carr · #6 12-02-2007, 02:41 PM

Quote:

Originally Posted by ToneRanger

Strings are just D'Addario 45-105 - not high tension; neck angle is OK, it's the curve I'm trying to get rid of. I'll try some washers and give it another tweak...

Flat or round?
If they are flats, try D'Addario XL Chromes (that's extra light). I have a couple of older Fenders that are way way happier with strings sets having a 100 gauge E string.

ToneRanger · #7 12-03-2007, 04:57 AM

Well I thought I'd give it another tweak before I try drastic measures. I took the neck off and removed the truss rod nut. Looking into the hole, it certainly looks like the nut has been working its way deeper into the neck. I found a couple of small washer that fitted, replaced the nut and cranked it a lot tighter than I've been game to in the past; I kept tightening until the neck wasn't moving any more. By this stage it had several mm of backwards curve.
I put the bass back together, tuned it up, and the neck is almost perfect! Just about 1 mm of forwards relief, and much more playable than it was. The test now is to see if it stays that way or returns to its previous shape by morning.
btw, the strings are D'Addario nickel roundwounds. Maybe I'll try a slightly lighter set.
(If it slips again, I think I'll get a plug-cutter and enlarge the nut-socket so I can use an over-sized washer. Not something I'd do to a vintage instrument, but this is just a new cheap neck so I'm not too concerned about collectible value)

62bass · #8 12-03-2007, 05:18 AM

Quote:

Originally Posted by ToneRanger

Well I thought I'd give it another tweak before I try drastic measures. I took the neck off and removed the truss rod nut. Looking into the hole, it certainly looks like the nut has been working its way deeper into the neck. I found a couple of small washer that fitted, replaced the nut and cranked it a lot tighter than I've been game to in the past; I kept tightening until the neck wasn't moving any more. By this stage it had several mm of backwards curve.
I put the bass back together, tuned it up, and the neck is almost perfect! Just about 1 mm of forwards relief, and much more playable than it was. The test now is to see if it stays that way or returns to its previous shape by morning.
btw, the strings are D'Addario nickel roundwounds. Maybe I'll try a slightly lighter set.
(If it slips again, I think I'll get a plug-cutter and enlarge the nut-socket so I can use an over-sized washer. Not something I'd do to a vintage instrument, but this is just a new cheap neck so I'm not too concerned about collectible value)

I'm glad it seems to have worked. The plug cutter is a very bright idea that should work well too.