Do I Need to Shim?

agreatheight · #1 01-27-2008, 11:12 AM

I recently installed a new Gotoh 201 bridge on to my MIM Jazz. I like it better than the stock (heavier, better quality imo), however, I cannot seem to get the bass set up well now. The relief on the neck is set OK (did the first fret / last fret test with feeler gauges) but the bass has high action on the higher frets with the saddles lowered nearly all the way. I am assuming this means I need to shim the neck, yes? Are there any resources out there for this?

Thanks!

GlennW · #2 01-27-2008, 12:19 PM

I think you need a shim. Find an old credit card and cut a piece off which will fit in the neck pocket between the two screw holes closest to the bridge and the end of the neck pocket. Cutting a short shim increases the neck angle a bit and makes a bigger difference in relation to the saddles than a shim of the same thickness which covers the entire neck pocket.

perucci · #3 01-27-2008, 12:23 PM

That is presumably the classic indicator for a shim; the saddles can't go any higher or lower (both can happen).

Note: The classic shim is whatever you've got: matchbook, business-card, pick, etc. In reading-up on this a bit, the preferred method seems to be using a piece of hardwood veneer that is tapered with a belt sander, to maximize neck/body contact.

GlennW · #4 01-27-2008, 12:32 PM

Good luck trying to sand a piece of wood about 3" long .030" to nothing.

perucci · #5 01-27-2008, 12:45 PM

Quote:

Originally Posted by GlennW

Good luck trying to sand a piece of wood about 3" long .030" to nothing.

I was wondering about that...

GlennW · #6 01-27-2008, 12:57 PM

IMO, that's one of those things that's sounds great on paper, but doesn't work so well in real life. If I was going to try that I'd use a mitre box.

You can get a taper by using layers of tape or sandpaper...longer pieces on the bottom and shorter ones on top...sort of like a squished stairway.

Turnaround · #7 01-27-2008, 01:27 PM

Quote:

Originally Posted by perucci

I was wondering about that...

Start with a piece of veneer about .030 thich. Use double-sided tape to affix it to a board that is about the same with and a bit longer, with the end that is to be the thin one right at the end of the mounting board. Taper the veneer with the sander then remove it from the board. Really not so difficult.

GlennW · #8 01-27-2008, 02:53 PM

I've never used double-sided tape...might have to get some.

agreatheight · #9 01-27-2008, 03:27 PM

OK, so I am not a woodworker, lol. I have no veneer or special sanders, etc. I have never had a bass that has needed this before and I doubt I'll need to do it again so I don't really want to buy any tools or materials. I'll take it to pro to get it done if I need to, but I think I'll try out the business card method first and see how it goes. I mean, it's a $250 mim jazz with a $30 aftermarket bridge, you know? I'd rather aviod buying stuff or taking it to a shop if possible.

So, anyone out there done a successful shim with a business card?

Thanks everyone!

perucci · #10 01-27-2008, 04:36 PM

I did a shim, but I removed it since I misdiagnosed my particular setup problem. I'll defer to others re: the specifics, but in general:

You shim the bridge side of the pocket if the saddles are currently "bottoming-out".
You shim the nut side of the pocket if the saddles are currently "topping-out".
Careful not to cross-thread those screws! "Feel" them as you re-insert them by hand; don't just use a power screw-driver.
You don't "over-torque" those neck screws! Over time, that will cause the "tongue" to bulge, making the upper frets too high.

agreatheight · #11 01-27-2008, 06:27 PM

The shim is in!

I used the thinnest card I could find (a laminated paper insurance card), put the shim in against the neck pocket and everything looks good so far. The saddles are now off of the bottom of the bridge and the action is more even up the neck, lower up high toward the bridge. I am buzzing a tiny small amount on the low end toward the nut, but I want to give everything a chance to settle before I tweak the saddles or the neck again. I'll update in a couple days with the full results.

Thanks all!

Giraffe · #12 01-28-2008, 04:36 PM

Quote:

Originally Posted by Turnaround

Start with a piece of veneer about .030 thich. Use double-sided tape to affix it to a board that is about the same with and a bit longer, with the end that is to be the thin one right at the end of the mounting board. Taper the veneer with the sander then remove it from the board. Really not so difficult.

I was surprised how well this worked when I first started doing it. They will split once in a while, but the veneer is fairly cheap and you can get species in enough variety that you can match the color of the body, avoiding a witness line where the bottom of the pocket is visible in the treble side cutaway.

I make up several at a time so they're at hand when I want it, and I just trim it to fit the pocket. These full pocket shims fully support the neck heel, helping avoid nasty ski jumps when the neck bolts pull on a neck supported only at the very top of the pocket and the strip of business card at the bottom. Someone like Stew Mac or LMI should start pre-fabbing them to save us some dust.

BartmanPDX · #13 01-28-2008, 09:12 PM

Quote:

Originally Posted by tombrien

Someone like Stew Mac or LMI should start pre-fabbing them to save us some dust.

Now that's a good idea right there.

BartmanPDX · #14 01-28-2008, 09:13 PM

Quote:

Originally Posted by tombrien

Someone like Stew Mac or LMI should start pre-fabbing them to save us some dust.

Now that's a good idea right there. I'd gladly pay a few bucks to get a decent premade one and not have to mess with it. They could offer two or three different "sizes" or thicknesses.