Backbow options....?

[Mike Marshall]

I have this Jazz bass where the truss rod is completely relaxed (meaning its unscrewed to the point where it contacts the body – no movement left). If I screw it the other way, it appears to be working. It does turn rather freely though, but I can see it moving itself inward, then gets to a point that feels like its building up tension and seems to be working. The problem is in setup. I only have like .006 relief. I need just a couple thousandths more but I don’t have it. I’m so close right now that its insane. What would you do?

I’ve thought about heavier strings. I have “Pure Blues” (45-105) on there now and I do have a small collection of DR strings stored up. (Lo-beam/Hi-beam/Fat beam). Which have the most tension?

Or would I have to go up to a heavier gage. Meaning a .110 vice a .107 “E” string?

Are there any home remedies. Considering how little movement I need I’d listen to them.

Is there anybody in the Philly area who straightens necks? Jez…. That just sounds expensive.

Trying to make large adjustments with a truss rod is not what they are intended for. If you can back off the truss rod, clamp it into to shape then move the truss in to hold that position it should hold. As suggested you may need to apply heat. I'm sure there is something on YouTube to watch like Erlwine in Ohio.

 

[DanDBassist]

I have this Jazz bass where the truss rod is completely relaxed (meaning its unscrewed to the point where it contacts the body – no movement left). If I screw it the other way, it appears to be working. It does turn rather freely though, but I can see it moving itself inward, then gets to a point that feels like its building up tension and seems to be working. The problem is in setup. I only have like .006 relief. I need just a couple thousandths more but I don’t have it. I’m so close right now that its insane. What would you do?

I’ve thought about heavier strings. I have “Pure Blues” (45-105) on there now and I do have a small collection of DR strings stored up. (Lo-beam/Hi-beam/Fat beam). Which have the most tension?

Or would I have to go up to a heavier gage. Meaning a .110 vice a .107 “E” string?

Are there any home remedies. Considering how little movement I need I’d listen to them.

Is there anybody in the Philly area who straightens necks? Jez…. That just sounds expensive.

Sometimes a higher tension set can help a minor back bow. If this does the trick, then a heavier string can have a lower action and may not feel much harder to play.

 

[DrBnz]

So it’s been an adventure and thanks plenty to some great responses. Some sounded wild but I woulda tried them all sooner or later. For your entertainment / education I’ll even admit to what all I did.

Yeah, I “flexed” the neck by hand a few times. I thought that worked a little but it was gone the next morning.

I like the idea to remove the rod and tension it up. That sounds like something I’d try but not tell anybody. But that was moved to the top of “the list”. Closely followed by clamping and heat.

I understood what a shim does and what your intention of the reverse shim recommendation was as well….. and I had some…. so I tried it anyways: First I put a .5 in there and I wasn’t paying attention and put it in the normal way. Soon as I strung it up, I could tell that was wrong. All strings were flat on the board and no amount to saddle adjust was gonna fix that. So I took it off and also realizing how drastic a move .5 made, I turned it around (reversed) and used a .25. No it did nothing for my relieve issue, but it does give me a much better angle on the strings (more parallel to the board – less divergent) so I left it installed.

I then went to Slinky .055 - .110. (vice .045- .107) That helped “just” enough. I even had to tighten the truss rod only about an 1/8th turn. Right now it plays fantastic. I’m impressed with what I thought was a basket case is doing so well. I mean it has the potential to be in the top 5 of the collection. The only problem I see is if I ever wanna sell it. I gotta disclose that this can’t take light strings. In fact if they were to go BEAD that would be even better.

Right now its great….. I don’t know what happens come winter time though.

 

[newfuture]

Not sure how you feel about doing a full fret job on your Murray, but the real fix for that kind of backbow is to pull the frets, put the soulscrew to the middle of its travel (extreme backbow), then re-radius the board and re-fret.
Its seems extreme, but its the right fix and will take much less than a year, and wont be trying to mush a 60 year old cut of wood into a shape it obviously doesn’t want to be in.

Thanks. Definitely a lot more effort than this bass deserves, but I appreciate the write up!

 

[Jogobass]

I'm surprised at how often I see people thinking a shim is the answer to a relief issue. And vice versa.

I didn't say it was THE answer. I suggested that perhaps it might be a solution.

 

[Engle]

I didn't say it was THE answer. I suggested that perhaps it might be a solution.

Fair enough. Raising the string height will reduce buzzing on a neck with no relief.

 

[MrLenny1]

FWIW. Try some penetrating oil on the nut & shaft. Let it seep & try adjusting again.
Go easy on it.

 

[Turnaround]

Respectfully, without examining the instrument, it’s really impossible to tell exactly what the issue is. The OP states that he has some relief, just not quite enough. Tipping the neck forward a tiny bit might solve the problem and get the action where he wants it.
Again, it takes a few minutes and is totally non-destructive, unlike heating and bending or just forcefully bending the wood into a shape it doesn’t want to be in.

Raising the bridge will have exactly the same effect as tipping the neck forward. Neither action corrects a bow. At best they are workarounds and do nothing to correct the underlying issue.

I didn't say it was THE answer. I suggested that perhaps it might be a solution.

It's not a solution. It's a workaround, and not a very good one. Raising the saddles accomplishes the same thing and is less invasive, but still a workaround.

 

[DrBnz]

UPDATE / Trivia: So last I spoke I had it strung up w Slinky .110-.045.... and it pulled on the neck enough to get relief I wanted. BUT..... the next day the neck had migrated over a bit more. 2nd day it did it again. Now I adjusted both times and now my E saddle is on the ground. So I took the shim out, re-set everything and its great now. I did have to give it another 1/8 turn on the truss rod. We'll see if the neck continues to move over...... So how did we get to this? I'm not too sure if it was always like this (I had just bought it) or if it was traumatized by the coast to coast trip it recently took with no tension on the strings. It probably sat like that a week. Some of that was bouncing around in the back of a UPS truck. That's my only guess. Right now its sweet..... so long as the neck stabilizes itself soon.
So for those of you that recommended overtightening the strings to bring the neck back, I'd have to say you're most likely correct.