Help! Adjusting and old PBC/Bunker tenion-free neck!

rogerbmiller · #1 03-03-2010, 05:59 PM

Does anyone here have experience with the older PBC tension free necks?

I just picked up an Ibanez ATK USA Custom shop model and the strings bottom out below fret #12. The neck needs some tweaking. Can anyone tell me how to adjust this neck? I don't think it works like the newer models.

There is a screw hole near the 17th fret but I cannot figure out wheter it takes a hex wrench or something else, and I am not sure if it even does anything for adjustments for that matter.

Thanks for your help!

RBM

Zooberwerx · #2 03-04-2010, 05:36 AM

Yes, I can help. How's your relief at the moment?

The PBC / Bunker is a strange agent as relief is "artificially" introduced by adjusting opposing torque betweenst the neck / FB and the internal tension free rod.

First thing you need to do is find the relief adjustment access port located dead-center of the heel (between the neck mounting screws). May have a small chrome plug in position. Remove the plug and insert the handle end of the appropriate hex key (forget the size). Its situated fairly deeply, that's why we're using the longer reach of the hex key. You should feel it engage / slip into place. IIRC, CW = increases relief, CCW = decreases relief / straightens.

Let me know if you have addt'l questions.

Edit: don't touch anything near the 17th fret!! This is an access port for the tension free neck's pivot / fulcrum pin! I'm familar with their removal but if you haven't done this before, ask for guidance. The aforementioned port is not part of the standard garden-variety setup but may come into play should any intensive TLC become necessary.

Riis

Zooberwerx · #3 03-04-2010, 06:29 AM

One more thing....

Like the Status line, the Bunker / PBC's tension-free relief adjustment has a "neutral" zone whereas the hex bolt will feel loose for about 1/2 - whole turn. At this point, the tension-free rod / neck alignment are paired and there is no opposing force in either direction, hence no resistance.

Reason I mention this is that people get rather excited, thinking they've snapped or stripped the rod.

Riis

rogerbmiller · #4 03-04-2010, 08:07 AM

Thanks Riis.

So that silver "button" behind the neck heel is a plug? Any idea how to remove it?

Again, thanks. This is very helpful.

RBM

Quote:

Originally Posted by Zooberwerx

One more thing....

Like the Status line, the Bunker / PBC's tension-free relief adjustment has a "neutral" zone whereas the hex bolt will feel loose for about 1/2 - whole turn. At this point, the tension-free rod / neck alignment are paired and there is no opposing force in either direction, hence no resistance.

Reason I mention this is that people get rather excited, thinking they've snapped or stripped the rod.

Riis

Zooberwerx · #5 03-04-2010, 08:13 AM

Quote:

Originally Posted by rogerbmiller

Thanks Riis.

So that silver "button" behind the neck heel is a plug? Any idea how to remove it?

Again, thanks. This is very helpful.

RBM

Drill press! Just kidding.

You should be able to slip your fingernail or fine-tipped jeweler's screwdriver under the lip and pry it up. The plug has spring-like appendages which extend a 1/4" or so into the hole. Its a tension fit, no threads or the like. May offer a bit more resistance than anticipated so be patient.

Don't remove the neck and attempt to adjust relief. The design requires the neck to be attached as there is a washer that fits between the neck heel and pocket.

Riis

Bassman1980 · #6 04-11-2010, 09:18 PM

Hey, I have the same Bunker ATK, but without a plug to access the adjustment screw. How do you setup the neck properly without it just being a game of trial-and-error? I know I'm going to need to remove the neck to access the screw.

Bassman1980

Zooberwerx · #7 04-12-2010, 04:05 AM

Quote:

Originally Posted by Bassman1980

Hey, I have the same Bunker ATK, but without a plug to access the adjustment screw. How do you setup the neck properly without it just being a game of trial-and-error? I know I'm going to need to remove the neck to access the screw.

Bassman1980

You have no access port? If the chrome plug is absent, you should still see a port. A Bunker neck cannot be tweaked if removed from the body as it removes a necessary "anchor" washer / locking nut from the equation. Any way you can zap me pics of the back of the bass, back of neck / headstock, please?

Do not remove the neck at this point. I'm serial.

Riis

Bassman1980 · #8 04-17-2010, 02:18 PM

Thanks for the reply, I've attached the pictures. I wouldn't believe it if I didn't have it.

-Bassman1980

Zooberwerx · #9 04-18-2010, 12:30 AM

Quote:

Originally Posted by Bassman1980

Thanks for the reply, I've attached the pictures. I wouldn't believe it if I didn't have it.

-Bassman1980

Now you're messing with my head. Basically uncool as I just got back from a gig plus I have 1 1/2 Vicodins on board.

The headstock pic shows the typical Bunker brass headcap / nut assembly and the reverse shot shows what appears to be the pivot / anchor pin access port on the side of the neck. No tension rod adjustment that I can see, either, which is perplexing. It is technically possible to not have a truss rod port provided the washer (washer / nut / cap screw assembly) is wedged between the neck heel and neck pocket. Any way you can take the neck off and snap some addt'l pics? You're gonna have to do it anyway from the ways things appear.

I may be a know-it-all but I don't know it all. I just say a pic of rogermiller's Bunker a few weeks ago and his has the aforementioned port with a chrome plug to make it look nice and pretty. We'll know more once you get the thing dismantled. Reminder: don't remove the side-mounted anchor pin unless absolutely necessary....its a PIA to re-install.

Riis

Bassman1980 · #10 04-18-2010, 07:32 AM

I'll try pulling it apart this afternoon when I have some time. I've had this bass for about 10 years, always liked the tone, but was frustrated by the high action with seemingly no way to adjust it. It sort of floated to the bottom of my rotation and went in the closet. I didn't realize it was a bunker until a short while ago. It has officially stumped at least 2 guitar techs who basically kind of shrugged their shoulders and went "I dunno".

Zooberwerx · #11 04-18-2010, 10:54 AM

Quote:

Originally Posted by Bassman1980

I'll try pulling it apart this afternoon when I have some time. I've had this bass for about 10 years, always liked the tone, but was frustrated by the high action with seemingly no way to adjust it. It sort of floated to the bottom of my rotation and went in the closet. I didn't realize it was a bunker until a short while ago. It has officially stumped at least 2 guitar techs who basically kind of shrugged their shoulders and went "I dunno".

Dave Bunker would be quite helpful in this arena...I've spoken to him in the past. Any chance this is a non-original body or some other type of mis-matched creation?

A good clean shot of the pocket is critical. IIRC, there should be a washer-sized countersunk depression which accommodates the adjustment washer and allows the neck heel to be flush-mounted without binding the washer. As mentioned, difficult to describe but I'd be glad to give you a call when you get the follow-up pics posted.

Check one more thing while you're at it. Insert the handle end of a hex key (size?...I don't recall) into the anchor pin port on the side of the neck / 19th fret. You may have to try a couple of different sizes. You should feel the hex key engage the hex head of the anchor pin. Doubt if you can see it even with a flashlight so you'll have to go by feel. Do not turn or remove....we just want to make sure the pin is present.

Riis

JAUQO III-X · #12 04-18-2010, 11:09 AM

Click the attached link and scroll down to the section called "To adjust the truss rod system" It's the same system you have. I own one of the Henman-Bevilacqua basses which has a licensed Bunker tension free neck system.

And scroll down to the section called "WHAT IS THAT HOLE DOING IN THE NECK?"

http://www.henmanguitars.com/index.p...tegory/how_to/

I'm a Henman-Bevilacqua endorser.

Zooberwerx · #13 04-18-2010, 11:47 AM

Quote:

Originally Posted by JAUQO III-X

Click the attached link and scroll down to the section called "To adjust the truss rod system" It's the same system you have. I own one of the Henman-Bevilacqua basses which has a licensed Bunker tension free neck system.

And scroll down to the section called "WHAT IS THAT HOLE DOING IN THE NECK?"

http://www.henmanguitars.com/index.p...tegory/how_to/

I'm a Henman-Bevilacqua endorser.

Excellent! Is one of the 5 neck mounting screws actually a plug? I can't tell by the photo angle but the suspect would have to be centered with the neck heel to allow straight-on access. The HB link you provided is pretty clear-cut.

Riis

Bassman1980 · #14 04-18-2010, 06:09 PM

Removed the neck. Weird. No washer, but there's an indentation where one likely resided. It looks like the screw was butted up against the heel to apply some tension. The screw does NOT look original, and it doesn't line up with any of the 5 screw holes that bolt the neck to the body. The 17th fret pin is still there.

kevin newsham · #15 04-18-2010, 06:27 PM

Somebody mounted a bunker ATK neck, to a non-ATK body. The neck mount screw holes in the neck tell the story. I would contact Dave Bunker to get the appropriate neck adjust screw, and washer, drill the correct access hole in the body, and enjoy your "hybrid" ATK.

You can contact Dave through his son at Treker guitars. Nice guy, and very helpful.

kevin newsham · #16 04-18-2010, 06:46 PM

Drill out the necks screw holes, glue maple dowels into the holes, and re-drill in the correct position. The way it sits now, the neck mounting is not very secure, and those screws could strip/ break into the extra holes very easily. All combined it is about an hours worth of work, but it will make all the difference in the world.

Bassman1980 · #17 04-18-2010, 06:48 PM

It's an ATK Body. It would appear that somebody "Frankenbassed" this thing from a Bunker neck and an Ibanez body? I've had it since 1998 or so, and it was far from sparkling new when I bought it.

Bassman1980 · #18 04-18-2010, 06:53 PM

What you're seeing as holes are actually dark alignment marker dots. That's exactly what I'd do if there were holes that close to one another though.

JAUQO III-X · #19 04-18-2010, 07:08 PM

Quote:

Originally Posted by Zooberwerx

Excellent! Is one of the 5 neck mounting screws actually a plug? I can't tell by the photo angle but the suspect would have to be centered with the neck heel to allow straight-on access. The HB link you provided is pretty clear-cut.

Riis

You have to take out one of the screws (in the neck) and deeper in that hole is where you would use the allen wrench to make adjustments.

Zooberwerx · #20 04-18-2010, 07:22 PM

Quote:

Originally Posted by kevin newsham

Somebody mounted a bunker ATK neck, to a non-ATK body. The neck mount screw holes in the neck tell the story. I would contact Dave Bunker to get the appropriate neck adjust screw, and washer, drill the correct access hole in the body, and enjoy your "hybrid" ATK.

You can contact Dave through his son at Treker guitars. Nice guy, and very helpful.

Yep. You can probably pull off a restoration provided you're good with tools. The cap screw, locking nut, and washer are probably available at your favorite hardware store but I'm not sure of the sizes so contacting Dave Bunker would be my #1 option. The pocket needs to be countersunk to accommodate the washer and a hole drilled clear through the body. I sure hope the threads in the tension rod weren't hosed by the insertion of the improperly sized bolt. Not to worry....I've plugged, drilled, and re-tapped a stripped rod.

Somebody should be shot. Forward the pics to Dave Bunker....worth a thousand words! Anywho....mystery solved.

Riis