I know, this sounds crazy. But when I tighten the truss rod on my late 70s Leo it bends the head away from the strings bringing the middle of the neck up closer to the strings. Does that make sense? It’s backwards from what it’s supposed to do.
Mostly this has been ok because if I tighten the bolt just enough to not rattle, the neck is almost perfectly flat and very playable. But recently I tried a lighter gauge string and now they buzz on the frets. If I could give just a hair of relief to the neck, it would be fine.
Before me this poor thing sat unused and hidden away for at least 30 years. Maybe this storage had something to do with it.
Is there any way to fix this neck? I know I can go back to the old strings or buy a taller bridge etc. But is there any repairing the problem?
If you haven’t already, try turning the nut/hex the other direction to see if it brings relief into the neck. I believe most truss rods are 2 way rods, meaning that will lengthen (adding bow) or shorten (adding relief) to the neck. If you’ve tried this and it didn’t work, I’d go ahead an just get a slightly taller bridge. Here's a good video explanation from Warren Yates:
Edited by - plars on 01/29/2023 06:41:52
If, as you say, you can loosen the nut and can tighten it just enough to prevent rattling, you probably don't have a 2-way rod. Few production banjos had 2-way rods in the 70s. The rod is working correctly. Tightening the nut should raise the center of the fingerboard toward the strings, ideally to a good, playable amount of relief but if the neck is already too straight it will not work to correct relief.
What you are doing (no tension on the rod, nut just snug) is the best you can do for controlling neck relief.
How high is the action measured at the 12th fret from top of fret to bottom of string? If it is lower than necessary raising the action may help with string buzz.
Edited by - sunburst on 01/29/2023 07:18:57
That makes sense. Thank you.
I have two Leo Fenders. They have one-way truss rod. Back off adjustment untill completely lose (lefty loosey about 1 turn) and don't worry if it rattles for awhile. After playing awhile I bet you will get relief (quicker with heavier strings). May take a few days.
When you get proper relief just snug it up to hold adjustment.
To tack onto what John/Sunburst is saying: The standard one-way rod from that era only helps the neck fight against string tension that could pull the neck into upbow (too much relief). So while it can help to flatten an up-bowed neck, or even over-correct into back-bow (what you've experienced), it can't introduce relief or force a neck into relief.
On a banjo with a one-way truss ord, only the strings pull the neck into relief. The truss rod helps to resist that force and keep relief to the right amount.
So loosen the nut a little at a time, retune the banjo to pitch, and stop when the relief is where you want it. You may have to check again in a few days as the banjo settles in with the lighter strings.
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