Neck adjustment, back bow, RM1999

[clasbas]

A question for those of you (probably all of you) who know this better than me:

If I check

with

and notice a significant back bow, most pronounced on the D/G side, would then this

be a good strategy to get the neck straight again? As you can see from the last photo, the E/A rod is loosened - just - and the D/G rod have some space to it in order to let the neck self-adjust from the tension of the strings. At least that was my thinking, but I am not sure I am thinking correct here.

I've tried to search the forum, but the only thread I found that goes into detail about the back bow issue did not have the situation of having to loosen the rods beyond having any tension at all, and obviously the technique with adjusting the neck with the hands and then tighten the rods do not apply here.

It do affect playing, there is significant buzz on the D string 2nd/3rd band and other places too - otherwise I would not care.

This is an RM1999 from 1964, FWIW.

[Dirk]

I'm pretty sure they aren't dual action or self adjusting rods, also the pictures don't show the neck bow. Look up the neck from the body end, use the rule to determine straightness on the fret tops across the fingerboard.

Use the classic rod technique by manually putting the neck where it needs to be, then tighten to hold in place.

It requires clamping the bass down, then also clamping the headstock with full string tension. You might have to try it a couple times.

If you leave it as is, that's the formula for a twist.

Good luck,
Dirk

[clasbas]

Use the classic rod technique by manually putting the neck where it needs to be, then tighten to hold in place.

It requires clamping the bass down, then also clamping the headstock with full string tension. You might have to try it a couple times.

OK, so this applies to a back bow as well? That was what I was unsure about, since if I clamp the body and the headstock I will get more back bow, as I see it. Maybe I am missing something here?

Here is a photo of the ruler position, when fully aligned with the frets at the body end.

As you can see, a significant back bow. The photo does not show, but it starts to happen about half the way to the nut.

If you leave it as is, that's the formula for a twist.

That is scary. I have tightened them now, carefully.

[pag]

Ive had three RMs and also done this adjustment to my CS. Just loosen the nuts off slightly and evenly..no need to unscrew them very much. Hold the bass body between your knees or use your foot to hold it against a sofa again between your knees. Ive done this with the strings on but slackened off by the way. Get the neck by the top of the fretboard forward of the nut with one hand and hold the heel end of the neck with the other. Bend the neck roughly how you want it (its quite strong and flexible) then use one hand to tighten the truss rod nuts..not too tightly! whilst holding the neck in position.Get the strings roughly in tune and if it looks good play it a bit then just leave it on a stand to settle. If the shape looks about right after some time just tweak the nuts a little tighter..again dont overtighten. If it bends back just do the routine again and take care not to put any stress on the nut area either with the wrench or your hand. I found it took me couple of goes before I got it right. Just take your time.

[pag]

By the way those nuts and the aluminium block look like replacements so Im not surprised at any movement. At least you are able to get the nuts to turn! I had a job and a half with DA24 as they were tight as hell!

[clasbas]

Ive had three RMs and also done this adjustment to my CS. Just loosen the nuts off slightly and evenly..no need to unscrew them very much. Hold the bass body between your knees or use your foot to hold it against a sofa again between your knees. Ive done this with the strings on but slackened off by the way. Get the neck by the top of the fretboard forward of the nut with one hand and hold the heel end of the neck with the other. Bend the neck roughly how you want it (its quite strong and flexible) then use one hand to tighten the truss rod nuts..not too tightly! whilst holding the neck in position.Get the strings roughly in tune and if it looks good play it a bit then just leave it on a stand to settle. If the shape looks about right after some time just tweak the nuts a little tighter..again dont overtighten. If it bends back just do the routine again and take care not to put any stress on the nut area either with the wrench or your hand. I found it took me couple of goes before I got it right. Just take your time.

I think I finally start to understand something that has eluded me through many googlings and searches in this forum. All the time, I have been under the misconception that the direction of the neck bow matters, and therefore that the back bow situation is different from the "normal" bow which is fixed with the "1. loosen, 2. adjust neck manually 3. tighten" method.

Thanks to you both for finally removing this illusion from me I will be able to do it the correct way then.

By the way those nuts and the aluminium block look like replacements so Im not surprised at any movement. At least you are able to get the nuts to turn! I had a job and a half with DA24 as they were tight as hell!

Yes, they are replacements from a repair in the early 70's. I should probably be thankful for that. However, the standard Rickenbacker tool does not fit these nuts so I had to assemble my own tool from various bits (literally) and pieces. But yeah, they really are easy to work.

Again, thanks!

[Dirk]

FYI the nut will always be taller than fret #1. So for me that pic doesn't help.

So you really need to look up the side of the neck with a rule to determine where it needs to be.

Glad it's making sense now, it's challenging to try and explain things in text only.

[lumgimfong]

You can also capo the first fret, press the last fret of the E string and then take a measurement between the top of the 9th fret wire and the bottom of the E string to see if the neck is in fact back bowed or front bowed.
Most people say you should just be able to slip a piece of paper or business card in there.
If there is no space and the string is in contact with the fret then indeed it is back bowed.