Author Topic: Double Truss Rod - One Loose? (Read 1297 times)

ox_junior · « **on:** March 16, 2005, 11:45:30 AM »

Here's a question:

My Spyder has two truss rods. Upon taking her out for her spring tweaking, the rod on the right (supporting the D and G strings) appears to be completely loose in order to get the super-low Entwistle-type action I want.

I don't want to turn my investment into expensive art. Will this mess up my alignment permanently?? This is making me nervous. It's a new instrument and we all know new Alembics do funny things sometimes, but this seems odd to me.

My guitar tech said this shouldn't be an issue but he's used to dealing with single-rod instruments. He felt I should ask the Alembic experts to be sure. So...I'm asking!!

Your opinions please...

Mike

rogertvr · « **Reply #1 on:** March 16, 2005, 11:51:14 AM »

That seems odd to me. I use lighter gauge strings than you, Mike (35-95) and to get the super low action I want on the DW, I still have a fair amount of tension in both rods to pull the neck back. Otherwise it would end-up looking like a banana and the gap from the strings to the frets would be enormous!

ox_junior · « **Reply #2 on:** March 16, 2005, 12:19:02 PM »

Yikes Rog! I hope I don't end up with a banana split.

Yes the left rod seems to be doing the job for the whole neck but this seems wrong to me. If I tweak the right rod even slightly, my G string becomes unplayable as it leans too far against the first fret.

Maybe a bridge adjustment is necessary in order to put a little tension on that rod?

We'll see what everyone else has to say...

rogertvr · « **Reply #3 on:** March 16, 2005, 01:07:34 PM »

For what this is worth, Mike, the bridge on the DW is flat on the brass baseplate. The nut is raised slightly across the board - and I do mean slightly. Next to no relief in the neck but both of those rods have tension in them. If I go too far with the tension on the rods, the strings appear to catch on the frets around the first octave mark but obviously it's difficult to state that categorically.

ox_junior · « **Reply #4 on:** March 16, 2005, 01:49:32 PM »

Thanks for the insight Rog. I'll check my adjustments to see if that helps but I'm obviously cautious. Even though I've played for a long time, I'm very new to making adjustments to instruments myself. Don't want to mess up on my Grand Prize! Like you said, your strings are lighter gauge than mine, which could be a factor.

Anyone...? Oliver?

Mike

David Houck · « **Reply #5 on:** March 16, 2005, 02:07:16 PM »

Whenever I've had loose trussrod nuts, I've just tightened them up to where they are just snug rather than leaving them loose. I don't think it's an issue, especially if the neck is where you want it. I tend to think, based on past experience, that if the neck is not where you want it and you would have loosened the loose side even more if you could, then the tight side is too tight and needs to be loosened.

David Houck · « **Reply #6 on:** March 16, 2005, 02:16:55 PM »

If you've had a recent change in humidity inside your house, you may want to wait a few days and let the humidity level out some before doing your tweaking. This winter, the humidity in my house has been consistently in the low 30's. Last week there was a dry spell and the indoor humidity dropped to about 29 for a day or two. This drop seemed to make a difference on my S1. But then I may have just been imagining things.

ox_junior · « **Reply #7 on:** March 16, 2005, 02:24:36 PM »

Not a major change in humidity, which is fairly constant here in sunny LA, although it seems our rainy season is over (for now at least).

I'll snug up that nut (boy does that sound deviant) and wait a bit to see if I get any more movement.

Thanks lads...keep those POVs coming in...

Mike

bob · « **Reply #8 on:** March 16, 2005, 02:40:46 PM »

It might be interesting to know how much tension you have on the left rod, i.e. fractions of a turn before the nut becomes loose.

If it's not a lot (don't know what that means precisely, but let's say not more than 1/2 to 1 full turn), and you're happy with the setup, then just snug up the right one so it doesn't rattle and forget about it.

If you do have a lot of tension on the left, then you might want to experiment and see if you can get proper relief with some tension on both rods. As a general rule, they should be fairly similar (and should have started that way), but it's possible that your neck just wants to twist.

(Oh, adjusting the bridge isn't going to make any difference on truss rod tension.)
-Bob

because · « **Reply #9 on:** March 16, 2005, 04:21:31 PM »

I don't have an answer for this but I am very interested in this situation. I have an Epic 4 and an Epic 5. The Epic 4 has both truss rods adjusted about the same and it plays fine. The Epic 5 has an imbalance in the rod adjustments whereby the D / G side is tightened about three or four turns more than the B / E side. That is based on the amount of exposed thread. A pic can be seen here:

http://bkos.home.infionline.net/GuitarStuff/Truss%20Rods.jpg

This bass plays fine. I just recently converted it back from EADGC to BEADG and only had to add about 1/4 turn to the B / E rod to get the action right.

It looks to me like the rod is either longer or is pulled in the neck. It's always been that way since I bought it ( used ), but I'm starting to worry about it. I e-mailed Alembic directly and they haven't replied. I hope they do but in the event they don't I'm open to any thoughts from this group on this situation.

David Houck · « **Reply #10 on:** March 16, 2005, 04:55:46 PM »

Welcome to the group, Bob. That's an interesting question and I don't recall seeing it discussed before; that doesn't mean it hasn't, I just don't remember it if it has.

valvil · « **Reply #11 on:** March 16, 2005, 05:52:50 PM »

Hello Mike,

we always tell customers to make truss rod adjustments in parallel; in other words, turn them by the same amount. You really don't want to turn them in different increments. If you tighten or loosen one more than the other, you might end up with twisted neck. The idea behind the dual truss rod is about increased stiffness in the neck leading to more stability. It's not about being able to make one side go lower or higher than the other.

Call me at work if you have questions.

Valentino

because · « **Reply #12 on:** March 16, 2005, 06:21:00 PM »

Hi Valentino:

Can you look at my photo via the URL in the above post and share your thoughts?

TIA

bob · « **Reply #13 on:** March 16, 2005, 09:59:26 PM »

Wow, that photo is strange (because) - it really does look like one rod is way longer than the other. Maybe they are different (the only other rational explanation is that one is pulling out, though that seems extremely unlikely and maybe even physically impossible...).

It sounds like you're not having any problems, so I'd be inclined to ignore it. If you're really curious, loosen them both, slowly and equally, counting the turns, and see if they become loose at about the same time.

Not wishing to get in trouble with our dear 'moder Val', while his statement is generally accurate about wanting to adjust both rods evenly, the picky side of me can't help saying that if one needs an extra 1/8 of a turn or so to suit you, that's fine. But much more than that, and you may be getting into dangerous (or at least undesirable) territory.
-Bob

bigredbass · « **Reply #14 on:** March 16, 2005, 10:26:08 PM »

I've never believed that both truss rods should be adjusted identically, as if we had a tiny torque wrench that could actually adjust both rods to exactly the same pounds/feet.

Here's why:

Several string catalogs quote string pull in lbs/ft individually on the typical 34 scale bass. These values always fan out with the most tension on the big Es and Bs to the least tension as we work up to the Gs and Cs. While different guaging can approach the mythical 'balanced set' (keep dreaming!), in general the low side of the neck will always be under more tension than the high side.

So under these conditions, adjusting both truss rods to the same torque would just have to put more 'bow' (relief) in the low side. This is not necessarily a bad thing, since the bigger strings vibrate in bigger arcs (think 'jumprope' here), but ultimately for anyone wanting the last millimeter of adjustment to get action so low you can just get a Bambu paper under the strings, you're still 'leaving some on the table'.

I've written extensively about neck adjustment. ALEMBIC honored me by including several in the FAQ/MustReads (Thanks, Mica, Dave!!). You might read through them. It's a huge comfort to me to KNOW how to do it, instead of trying to find a guitar tech who 'gets it'; lots of GREAT guitar techs are hapless when you tell them you want 'low action on a BASS???!!??'.

In the mean time, I agree with Bob: Just snug it up so it won't rattle! Typically if it's too tight, you'll hear that awful popping/cocking sound, at which point you IMMEDIATELY back off !

Overarcing all of this: No two basses will adjust identically because wood is not repeatable structurally (My favorite Mica/Susan-ism: The wood will one day realize it's no longer a tree. . .). Each bass will have it's own idiosyncracies, tone and adjustment-wise
(and at its birth, how easily it sawed, sanded, and finished). Maybe on your Spyder you could use a 105 for a G and it wouldn't take much truss rod! It's the wonder and mystery contained in the beauty of wood.

Incidentally, on any new bass, I ALWAYS remove the nut completely (ANOTHER priceless Dan Erlewine tip), and lubricate the threads with the smallest drop of BreakFree CLP. I love to buy used, overlooked basses in great shape, and it's not uncommon the truss rod was never touched before, so I want to nab any corrosion fast.

J o e y