4001 Truss rod question

[silverjet89]

So, I've been slowly restoring my '75 4001 and I decided to pull the truss rods just to see what shape they were in. The threads look pretty good but the rods are curved in a slight U shape. Is this normal or should they be straight when removed? I did have a bit of trouble getting the neck adjusted when I first got the bass and wondered if this might be part of the problem.

Thanks,
Kirk

[xsubs]

A bend is normal, but you may wish to straighten them out, if the bend is affecting your neck.
Just be sure to apply gentle pressure, so as not to kink it. It doesn't have to be perfectly straight, just a close approximation will do.

[johnallg]

If the U shape is quite pronounced, yes it would affect adjusting the neck especially when the arc is in the wrong direction.

[silverjet89]

The U shape is pretty pronounced. The ends are about 2" higher than the center. It is in the correct direction, though. I still had a hard time getting the neck adjusted close to flat. Do you think new rods would improve the adjustability? I doubt I can straighten these.
The neck is pretty straight with the rods removed. However, there is a very slight hump around the 3rd fret. I'm sure this is due to the fact that the rods had been adjusted improperly before I got the bass. There was a small crack at the headstock/nut area that had to be repaired for this reason.

[ilan]

The ends are about 2" higher than the center.

I thought It's supposed to be the other way. The truss rods in my '73 are curved a bit with the middle higher than the ends before inserted back inside the neck. It was a ski-slope neck before I started with it and now it's arrow straight with light gauge rounds, and very stable over time.

Here's a large pic of the truss rods when I pulled them out of the neck:
http://65.23.158.135/userphotos/photo.php?id=36319

A smaller version:

[rictified]

You are right Ilan,that's how they are supposed to look,they are supposed to be bent, if they aren't you'll have a hard time getting them back in. I have actually bent them more than that before to get them back in easier. The initial bend probably happens as you are pulling them out, not sure though, but I've never had one with a backwards bend and I've pulled a lot of them in my time. Once in the bend has no bearing on how they work anyway, there is an extreme amount of pressure in there. When tightened they separate which pushes the neck up in the middle, this is how your neck straightens out in a 4001. It fills the cavity and there is no other way for them to go when tightened except to straighten out the neck. It was actually a very ingenious idea. The only problem was they never had a way to keep the block from tipping which allowed the ends of the rods to raise up which put pressure on the nut area immediately above the ends.

[butike]

Hello, this is my first post in this forum. I have a '78 4001 which has the usual truss rod problem. The previous owners had used Rotosounds, probably for most of its life and when I got the bass the action was quite high and not at all pleasant to play. The rods are angled back, nearly touching the wood at the headstock end so that it's impossible to turn them with the trussrod adjuster tool. I have previously undone them as carefully as possible using pliers and did manage to improve the neck relief to some degree. I now have it fitted with Thomastik Infeld flats and It plays a lot better, the neck relief is now about 1mm at its worst point but I would like to get it dead flat. is there anything I can do to solve this problem? Any tips, solutions would be much apprteciated.

[heinpete]

Hi Owen,

welcome to the forum.
Have a look here: http://www.joeysbassnotes.com/Rick%20maint.htm#cmod
These are forum-proven advices!

[jps]

Welcome Owen,

1 mm of relief is fine really, you do need a bit of relief for the swing of the strings not to hit the frets. The flat neck concept is better suited to guitars, IMHO.