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How do I know how much I can tighten a truss rod?

Thom Fioriglio

Thom Fioriglio

Oct 24, 2019
1,744
3,867
58
Long Island, NY
#1
Hi all, it's that time of year when the dry winter air has caused my necks to curve a bit. My string height, measured at the 17th fret is usually around 4/64 is now at 6/64. And the action all over the neck is higher. I know I need to tighten the truss rod but I am always hesitant on how tight I can go. I loosen the strings before tightening, but there is resistance and it just makes me nervous to overtighten it or snap it.

I own three Fender Precision basses - a Tony Franklin Fretless, an Am Pro II and a new Vintera II Road Worn. The Am Pro II and TF Fretless both wear DR Sunbeams and adjusted easily with a quarter turn. The Vintera II has Labella flats and I've adjusted the neck twice already since I got it, a month ago and I still have some curve in the neck.

Can you snap a truss rod? Can over tightening damage the truss rod?

Thanks for any help.
 
#3
Loosen the 1/4 turn rod first. Then flex your neck. Then tighten it 1/4 turn. Note the resistance. You then have a feel for how much force you are using. Continue tightening as needed as long as the force required doesn’t increase you are still on clear threads. Also note that at the end of the threads, their depth gets shallower, they taper in depth from flat rod sides to full depth threads. So, the nut will jam on the grooves long before the rod will twist and snap as long as you have a feel for when the required force is increasing.

A new Vintera should have plenty of threads available. As the wood under the nut crushes with time and many adjustments the nut will recede into the bore. That is not the rod stretching, it’s the wood crushing. Keep on pre-flexing your neck, it actually straightens the rod and pushes the nut away from the wood it bears against. Consider also that the nut rotating against the wood bends the wood cells over and breaks them off: many old Fenders have receded nuts exactly because they’ve been cranked on without pre-flexing and wood has sheared off/crushed. Pre-flex makes your flex do the work and you merely move the nut into the location it needs to be to hold the neck in that relief, not relying on the nut to move the neck. Also keep in mind that if you notice the nut receding at all, a washer under it will fix that.
 
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#4
No, DO NOT loosen your truss rod, all adjustments need to be done under normal load.
A proper working modern dual action rod should adjust easily in either direction, and you should not feel like the wrench is bending at all, that's too much torque.

You can tighten until it no longer moves, if that's not enough then you can assist it into place.
Clamp body to something, than use another clamp to pull the headstock into place, then tighten truss rod.

Oh and yes indeed too much pressure can snap a rod. Also make sure you are using an absolute perfect sized tool for your rod, hopefully the one that came with the bass.

Best of success.
 
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#7
As I understand it, the truss rod is there to keep your neck at the correct level of straightness, and any effect on the action height is a by-product of the straightness adjustment. So first you’d measure the relief in the neck (fret string at first and last fret, measure at 12th) to see if that has grown.

If so, only adjust as much as needed to get that back in spec. 1/8 of a turn is a significant change, 1/4 is a lot. Small adjustment, massage the neck a bit as @96tbird suggested and re-check.

If the action is where you want it after the neck is right, then good enough. If. Not, other setup work might be needed.
 
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#10
Thom Fioriglio said:
Thank you all. Some really great advice. I’ll be doing this later. My goal is to have a business card spacing under the 7th fret. I do have feeler gauges but I find those too difficult to get a good reading.
Click to expand...

I use the "feel" in "feeler" when inserting the leaf(ves). I separated my kit and glued each to a mini-clothes pin. Capo on top of the first fret, depress at the 17th-19th. As others have mentioned, clamp the body between your knees and flex the neck backwards while tightening the TR. Slacken the strings as necessary...I don't as I'm impatient.

Riis
 
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#12
Resistance is normal for a truss rod under load, but you should never force it because rods can break, the anchors on the other end can crush the wood they're embedded in, fretboards can crack.

Worth reading the articles and watching the videos here if you're not comfortable making the adjustments:

Hambone

Thread 'ALL BASIC SETUP QUESTIONS ANSWERED HERE'

Here's some instructional sites to help you perform your own setup on your instrument :

support.fender.com

How do I set up my bass guitar properly?

FENDER® BASS ADJUSTMENT AND CAREThe following setup procedures and specifications are for you Fender bass as equipped with the strings that come on the instrument as standard equipment from the fac...
support.fender.com support.fender.com

[Invalid or Expired Link Removed]

Premier Guitar - Bass Setup Article | TalkBass.com

Jerzy Drozd setup guide

Some cool videos on the topic :

Lakland Bass Setup Video Part 1

Lakland Bass Setup Video Part 2

TB thread:

I need help!! 1960's fender jazz bass tug bar and ashtray hole positioning | TalkBass.com

Premier Guitar - Bass Setup Article |...
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#14
Thom Fioriglio said:
Hi all, it's that time of year when the dry winter air has caused my necks to curve a bit. My string height, measured at the 17th fret is usually around 4/64 is now at 6/64. And the action all over the neck is higher. I know I need to tighten the truss rod but I am always hesitant on how tight I can go. I loosen the strings before tightening, but there is resistance and it just makes me nervous to overtighten it or snap it.

I own three Fender Precision basses - a Tony Franklin Fretless, an Am Pro II and a new Vintera II Road Worn. The Am Pro II and TF Fretless both wear DR Sunbeams and adjusted easily with a quarter turn. The Vintera II has Labella flats and I've adjusted the neck twice already since I got it, a month ago and I still have some curve in the neck.

Can you snap a truss rod? Can over tightening damage the truss rod?

Thanks for any help.
Click to expand...
IMO it goes like this: if you can’t get to a correct stage of playability without threatening to snap the trussrod, then either the neck or the whole bass needs to go to someone else.

Yes, trussrods can be snapped. Threads can be damaged, trussrod nut hex sockets can be stripped. Etc.

I just went through this with a Squier CV Jazz neck. After a LOT of effort to salvage it, there’s a @ 3mm gap at the 12th fret. Is that optimal? No. Is it very playable? Yes. I will not be able to turn it further without damaging it, so that is its final adjustment.
 
#15
Thom Fioriglio said:
Hi all, it's that time of year when the dry winter air has caused my necks to curve a bit. My string height, measured at the 17th fret is usually around 4/64 is now at 6/64. And the action all over the neck is higher. I know I need to tighten the truss rod but I am always hesitant on how tight I can go. I loosen the strings before tightening, but there is resistance and it just makes me nervous to overtighten it or snap it.

I own three Fender Precision basses - a Tony Franklin Fretless, an Am Pro II and a new Vintera II Road Worn. The Am Pro II and TF Fretless both wear DR Sunbeams and adjusted easily with a quarter turn. The Vintera II has Labella flats and I've adjusted the neck twice already since I got it, a month ago and I still have some curve in the neck.

Can you snap a truss rod? Can over tightening damage the truss rod?

Thanks for any help.
Click to expand...
Have you measured the relief?
 
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#19
humbuckaroo said:
The way I do it: quarter turn, let rest for an hour and check relief. If it's still too much, one more quarter turn, let rest for an hour, check again. If you need more than half a turn, you've got a problem.

I don't turn mine if there's resistance. My truss rods have always been easy to turn.
Click to expand...
This but maybe let it be 2 hours after 1/4 turn: neck needs to settle
If you keep tightening and checking action at once may snap rod or after bass settles you will have back bow

Doing it this way may need less turns than you think and keep Rod out of danger🙂
 
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#20
Nebadon2000 said:
This but maybe let it be 2 hours after 1/4 turn: neck needs to settle
If you keep tightening and checking action at once may snap rod or after bass settles you will have back bow

Doing it this way may need less turns than you think and keep Rod out of danger🙂
Click to expand...
Thanks! I did this with the Am Pro II and Tony Franklin. I tweaked them last night and ⅛ of a turn and let them be. I checked them this morning and they were all set. For the Vintera II that takes a little work to get to the truss rod. Will do that now and check on it later tonight
 
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