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'72 Fender pbass truss rod issue

A

agershark

Feb 13, 2024
15
3
#1
Hello All,

It's been recommended that I also post this here. Hopefully someone can help out...

...

New here, so I hope this is an appropriate question. I have a '72 pbass that I bought new back in the day. Wanted to have it setup recently. Was unable to move the truss rod nut to adjust, so took it to a luthier for help. Unfortunately when he tried to back out the nut, the rod unscrewed from the anchor, and the truss rod now slides right out - seemingly without a lot of effort - like perhaps there is no bow to it. Bad news... I know. The rod is not broken & the threads on the anchor end look good; just looks like it backed out.

It's a maple neck, with a Rosewood fretboard... so no skunk stripe.

A couple of questions...

First, I'd like to understand better how the truss rod in the pbass is constructed. When the bass was made, how is the bend put in this single-action rod to begin with? I've searched on line for specifics, but can't find any useful details. One Fender truss rod image and one replacement video for Fender guitars seem to show a kind of standoff in the middle of the neck creating the bow? And other pics show a curved channel routed in the neck? But I can't find anything showing how the pbass is done. Can anybody describe to me how it was constructed?

And second... I'm screwed, right? Or is there a way to somehow get the threaded end back in the anchor?

Thanks,
Mark
 
#2
It’s my understanding that Fender cut a curved channel in the neck, installed the truss rod, glued a filler strip over the rod that had a matching curve. Depending on the era this was done from the front or back of the neck.

You’ll need to access the truss rod anchor to fix this. The rod should have been attached to the anchor, I believe by having extra sticking out of the anchor then peening that over but I could be mistaken. It could possible to fix by cutting out a small section of the nut end of the fretboard, repairing the anchor and gluing the fretboard piece back on.
 
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#3
That stand off is only put on select guitars these days. They were tried on basses a couple times in the last century but deemed unnecessary. Present day bass truss rods in Fenders are a straight piece of steel placed in a bowed channel. As the truss rod is tightened the rod pushes against the central hump in the channel and forces the neck to bow back, reducing relief.

As far as repairing your truss rod goes, first I would get the nut you adjust free from the rod. Then you could try sliding the rod back in the pocket and try rethreading it into the anchor. If you can do that two or three times with minimal effort, then put a light coat of Red loctite on the anchor end of the threads and rethread the rod into the anchor. Finally apply a small, I mean minute, dab of Never Seize to the nut and put it back in. Let the Loctite cure a couple days before you attempt to adjust the rod.

If you do a search here there is a thread about this. Someone pulled a couple frets and managed to remove the fretboard between the two frets to access the anchor and make the necessary repair. They then reattached the fretboard (original piece? I don't remember) and refretted.

I think this is the thread I'm speaking of, see post #6:
https://www.talkbass.com/threads/72-fender-pbass-truss-rod-question.1630788/#post-27981214
 
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#4
Thank you for the replies!

The main reason I'm asking about the construction is that the luthier said the rod slid out so easily that he didn't think there was any bow to it. Which seems impossible... so thought I'd ask how it was done. I'm going to get the neck back from him tomorrow and see for myself what it looks/feels like. Hopefully it has the filler strip mentioned above... if so, that would give me more hope. If there is a standoff, I don't know how I could get it angled properly to get is screwed back into the anchor block.

The nut is now free from the rod.

Is loctite enough to hold the rod in place securely? The luthier here initially suggested drilling a hole in the fretboard, then once the rod was screwed back in to drill a small hole in the anchor/rod and inserting a pin, then repairing the fretboard (don't know how feasible drilling the anchor/rod hole that would be?). But because he didn't think there is any bow to the rod, he didn't think there would be any point in doing it.

I looked a bit for a related thread, but didn't readily see anything. But, I'll do a more thorough search. Thanks for pointing that out!
 
#5
agershark said:
Thank you for the replies!

The main reason I'm asking about the construction is that the luthier said the rod slid out so easily that he didn't think there was any bow to it. Which seems impossible... so thought I'd ask how it was done. I'm going to get the neck back from him tomorrow and see for myself what it looks/feels like. Hopefully it has the filler strip mentioned above... if so, that would give me more hope. If there is a standoff, I don't know how I could get it angled properly to get is screwed back into the anchor block.

The nut is now free from the rod.

Is loctite enough to hold the rod in place securely? The luthier here initially suggested drilling a hole in the fretboard, then once the rod was screwed back in to drill a small hole in the anchor/rod and inserting a pin, then repairing the fretboard (don't know how feasible drilling the anchor/rod hole that would be?). But because he didn't think there is any bow to the rod, he didn't think there would be any point in doing it.

I looked a bit for a related thread, but didn't readily see anything. But, I'll do a more thorough search. Thanks for pointing that out!
Click to expand...

Loctite is so strong that you are liable to shear/twist the trussrod off before the Loctite will give.
 
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#7
agershark said:
Thank you for the replies!

The main reason I'm asking about the construction is that the luthier said the rod slid out so easily that he didn't think there was any bow to it. Which seems impossible... so thought I'd ask how it was done. I'm going to get the neck back from him tomorrow and see for myself what it looks/feels like. Hopefully it has the filler strip mentioned above... if so, that would give me more hope. If there is a standoff, I don't know how I could get it angled properly to get is screwed back into the anchor block.

The nut is now free from the rod.

Is loctite enough to hold the rod in place securely? The luthier here initially suggested drilling a hole in the fretboard, then once the rod was screwed back in to drill a small hole in the anchor/rod and inserting a pin, then repairing the fretboard (don't know how feasible drilling the anchor/rod hole that would be?). But because he didn't think there is any bow to the rod, he didn't think there would be any point in doing it.

I looked a bit for a related thread, but didn't readily see anything. But, I'll do a more thorough search. Thanks for pointing that out!
Click to expand...
lol. Your “luthier” needs replacement because they apparently have no idea how a trussrod works.

Of course there’s a bow in the rod channel. I wouldn’t trust any more work to someone I have discovered doesn’t know his craft.
 
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#8
Well... to be fair, this is a very experienced, highly respected luthier. And yes, he does know how a truss rod works. It's more likely that I am just not doing a very good job of explaining the situation.

My questions were asked to try and give me a better understanding of the truss rod construction of this particular instrument... so that I can figure out why it is that the truss rod basically just slides out of the neck without resistance. That just doesn't seem likely if it is constructed the way I thought it would be.

Anyway, I'm not gonna say any more until I have it in my hands and can see for myself what he is talking about. Hoping to pick it up tomorrow, and will report back with what I find. Perhaps I am just not understanding correctly what he is saying.

Thanks again for any feedback.
 
#9
Here’s a link and some pictures that will hopefully help. You can see the curved channel the truss rod sits in. As the nut gets tightened up the rod tries to straighten out and creates a force that opposes the pull of the strings. It’s quite normal for this type of truss rod to slide comparatively freely in the channel. What it should not do is come out of the anchor.

http://www.timeelect.com/54-neck.htm

There’s some good cutaway pictures in the above link although I wish they would have shown a full length view of the cutaway neck.

IMG_8847.png IMG_8846.jpeg IMG_8845.png
 
#10
I have had truss rods back out of two different ‘71 Fender rosewood fingerboard necks. You will NOT be able to thread the truss rod back into the anchor without removing the piece of fingerboard between the nut and first fret. Best done by an experienced luthier!
 
#11
This is probably not the best place to bring this up, but it's kinda relevant. Though most single action rods rely on being imbedded in a curved channel, it's not strictly necessary for the channel to be curved. The idea is that when the truss rod is tightened, under tension it will straighten out and in doing so will push the neck up in the middle. But if the rod's channel were cut straight and the neck bowed, we would have the same condition - the truss rod would be bowed too. Tightening it would straighten it and the neck.

The reason the channel is curved is that it gives a little more mechanical advantage to the truss rod when it is put under tension - i.e. it makes it easier for it to do its job.

The illustration provided by Matt is fitting except that a 72 Fender Precision has the adjustment nut at the heel of the neck and the anchor near the first fret.
 
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#12
Turnaround said:
This is probably not the best place to bring this up, but it's kinda relevant. Though most single action rods rely on being imbedded in a curved channel, it's not strictly necessary for the channel to be curved. The idea is that when the truss rod is tightened, under tension it will straighten out and in doing so will push the neck up in the middle. But if the rod's channel were cut straight and the neck bowed, we would have the same condition - the truss rod would be bowed too. Tightening it would straighten it and the neck.

The reason the channel is curved is that it gives a little more mechanical advantage to the truss rod when it is put under tension - i.e. it makes it easier for it to do its job.

The illustration provided by Matt is fitting except that a 72 Fender Precision has the adjustment nut at the heel of the neck and the anchor near the first fret.
Click to expand...


Yes, and I’m aware where the adjuster is. I have a ‘76 P bass. I was just looking for some decent pictures. Hopefully I didn’t cause too much confusion.
 
#13
Many thanks coalbass for sharing your experience. It's good to hear from someone who has dealt with the same issue (although I'm sure you didn't think it was good at the time!). I suspected it was unlikely that I would be successful in blindly screwing the truss rod back into the anchor. And I suspect that's what sissy kathy was hinting at in her first post.

A couple more questions... if you don't mind...

- Once the truss rod came loose from the anchor, did you find that the rod slid out very easily? It seems odd to me that it would.
- On the two you had repaired, were they able to reuse the rosewood that was removed? Or was a new piece fashioned?
- Did you use loctite to fix the rod back in the anchor, or was another method used?

And Turnaround... thanks for your comments as well. I wondered about what you are saying... if when under string tension and bowed, if a "straight" channel would be curved enough that tightening would re-straighten. This seems less than optimal though. As I've been using the bass for 50+ years, you'd think it would have been right at one time! ;)

And thanks Matt for the images! I had found those (along with a couple of other related full length images). Just wasn't sure if my pbass would be the same.

Anyway, I'll report back with what I find.
 
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#14
agershark said:
And Turnaround... thanks for your comments as well. I wondered about what you are saying... if when under string tension and bowed, if a "straight" channel would be curved enough that tightening would re-straighten. This seems less than optimal though. As I've been using the bass for 50+ years, you'd think it would have been right at one time!
Click to expand...
The straight channel will be curved when the neck is bowed. But it will take a lot of tension to straighten it if the curve is slight. A curved channel offers more mechanical advantage.
 
#19
You can see a great pic of what the anchor nut looks like here:
Dave Bush Guitar Works
Yes, a good luthier will be able to get the section of fb off with no damage and reuse it. It should not be necessary to remove the very end of the fb on the headstock side of the nut. That is missing in the one picture because a less skilled luthier the neck first went to hacked the fb section removal.
 
#20
Yes, the truss rod pulled out of the neck pretty easily in both cases. Another good Luther in the Columbus area has had to do this repai as well to several early 70s P necks, leading me to wonder if Fender stopped doing anything to secure the truss rod into the anchor during these years. The scenario goes like this:
1 as recommended, you try to loosen a truss rod nut on a vintage Fender first to make sure it is free.
2 if the truss adjusting nut had become, seized on the trust rod over the years, loosening it easily unthreads the trust rod from the anchor nut.
3 when you pull the adjusting nut out of the neck, the truss rod comes out too
 

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