Fun with the 4001 truss rod system

[Colonel Sanders]

After receiving my steel block from Guitar Angel in the UK, I decided to bite the bullet and fix the truss rods of my 77 Autumnglo. The rods were very easy to pull out. I was expecting much more of a fight actually! I straightened the ends, did a quick re-threading and also filed the other un-theread end in a more chisel shaped.

Put these back into the bass. Again, that was fairly painless. Then went for my first ''Oooops''. The block was drilled for a 7/16 spacing between the rods (center to center) while my bass is having a 3/8'' spacing. So Guitar Angel will send a replacement.

Meanwhile, I use the original aluminum bloc and it is working just fine. The nuts are not bending downward anymore and I can fit my nutdriver to adjust the rods. Adjusting the neck the proper way was very easy and I was surprised how little tightening you require to ''lock the neck'' in place.

All in all, it took me about an hour to do this. That was time well invested. The neck is dead straight.

As much as I have cursed about the truss rod system of the 4001, when fixed and then adjusted the way it should be, it does the job allright. I which I would have done that on my previous 4001.

[Seans]

Easy when you actually get in there . I usually add washers to help the seat of the nuts on the block, avoid any digging in etc etc.
The chisel end may not help ( depending on how sharp an angle), as it acts like a tapered lock on the other side of the rod, ie both fighting for a place in the hole in the block and the taper forcing the thread against the side of the block.

[ken_j]

I believe it was designed with the aluminum block so that the nut would dig in a bit to prevent them from loosening. I'm not so sure the steel block is the way to go.

[Colonel Sanders]

I believe it was designed with the aluminum block so that the nut would dig in a bit to prevent them from loosening. I'm not so sure the steel block is the way to go.

Good point! The issue with the rods and nuts bending down is probably more about the aluminum block rotating because it is narrow. I guess a thicker block would actually achieve the same thing that the steel block is trying to achieve.

[Colonel Sanders]

Easy when you actually get in there . I usually add washers to help the seat of the nuts on the block, avoid any digging in etc etc.
The chisel end may not help ( depending on how sharp an angle), as it acts like a tapered lock on the other side of the rod, ie both fighting for a place in the hole in the block and the taper forcing the thread against the side of the block.

I did put washers. The tapered end, in my view help with applying pressure closer to the center of gravity of the blocks, minimising the moment applied on the block (assuming the tapered is done correctly). Chisel is probably to strong a word as the angle I gave is quite shallow. With the soft aluminum used for the rod, an acute angle would just make sure the chisel end would ''collapse'' under stress (for the lack of a better word). My aim was to minimise block rotation is to apply the load as close as possible to the edge of the hole as possible.

[rictified]

In the past I have found mine have bent back down over a period of time, the block would tip which would bend the tips down. This was caused by too much pressure from the back of the rods pushing against it. This was usually caused by too much string tension.

[Colonel Sanders]

This was usually caused by too much string tension.

Currently the bass has a really old set of Dean Markley Blue Steel 105 to 45. By the feel of it, the tension must be pretty close to the Roto Swing Bass 105-45 I will soon put on the bass. From memory, the Swing Bass are at 152 lbs of tension. I seem to recall that the 4001 could handle up to 156 lbs (give or take some lbs due to wood and glue variability from bass to bass).

I tweaked it a bit more this morning, getting rid of a annoying buzz coming from the bridge. It plays like a dream. As the frets do not show any sign of wear, I could bring the action very low. Those 4001 from the 70ies are rippers.

[johnallg]

..... Those 4001 from the 70ies are rippers.

SHHHHHHHHHH!!!!!!!!!!!!!

[T.A.R.]

I love reading threads like this. The RRF to the rescue yet again!

[Colonel Sanders]

I love reading threads like this. The RRF to the rescue yet again!

The amount of info shared on this site is outstanding.