Neck Shimming and Neck Relief questions

[Timko]

The Premier Guitar article this month got me interested in trying to shim my neck. While my Jag plays pretty well, the tension and action you get with a high break angle sounds really interesting to try. I have a couple of full neck shims from StewMac (.5 and 1 degree). I wondered if there's a way to determine what size shim would be best to start with. Has anyone used these shims on their offset?

The guitar I'm working on is a Johnny Marr, with the truss for adjustment in the heel of the neck. I had my guitar professionally set up, so I've not done and adjustment on it. Assuming that I may need to adjust the neck with the shim (which may not be the case), can I loosen my strings up enough to remove the neck without removing the string? It may be a dumb question, but I don't want to damage the neck or body.

[andy_tchp]

Hiya,

Choice of shim size is really trial and error. If the bridge is adjusted reasonably high off the guitar already I'd try the smaller one first.

All else being equal shimming shouldn't change the relief necessitating a truss rod adjustment; you should only need to raise the bridge to obtain the desired geometry and action.

You can slacken the strings right off without removing them completely to loosen the neck screws then tilt it up to access the truss rod adjuster. A capo is useful to hold them in place.

You'll have a difficult job getting a full pocket shim in there without removing the neck fasteners/neck from the body entirely though

[Webrocker]

hi,
I think the JohnnyMarr is already "tilted", without a shim. I once tried to install a Mastery on one, and compared to a "regular" old Jazzmaster, it needed to be setup way higher, exactly like when the neck of the JM was tilted by shimming. Taking into account how many little tweaks the Marr Model has, I wouldn't be surprised if they routed the neck pocked so that the neck is slightly pre-tilted. So maybe shimming a MarrJag isn't neccessary.

[theworkoffire]

...can I loosen my strings up enough to remove the neck without removing the string? It may be a dumb question, but I don't want to damage the neck or body.

Yes - as suggested, use a capo. You can normally remove the neck screws with the guitar on its side. Loosen all 4 screws without removing them, then remove them carefully one by one with your hand supporting the neck at the heel end so it doesn't move in the pocket (you can also use a gentle clamp). Once the screws are out, you can wriggle the neck gently upwards out of the pocket. I normally find I haven't loosened the strings quite enough at this stage, so make sure they're good and floppy.

[Timko]

Great to know about the strings. I couldn't imagine restringing the guitar each time I needed to make a neck adjustment.

Looking at my Marr, I believe that it may have angle in the neck pocket, but I'm going to call Fender today to see if I can get an answer.

[fisonic]

The .5mm shim give a fairly big change to kneck angle. Only really usefull if your kneck already has a few shims & needs more angle. You'll know you have too much angle if the strings are touching the bridge body or intonation screws, rather than the saddles themselves. If you have a mastery or other fixed bridge setup, you don't really want too mich angle, as you want the strings to slide over the saddles.
If it's playing well, why bother. Sounds like a solution looking for a problem.

[Timko]

I called Fender this weekend. Their support line told me that the diagrams for the body how a 91.9 degree angle where the neck pocket meets the body. He told me that the ARVI '65 Jag has the same touting as well. I assume that this means there almost a 2 degree shim routed into the pocket.

[BurgMistTort]

hi,
I think the JohnnyMarr is already "tilted", without a shim. I once tried to install a Mastery on one, and compared to a "regular" old Jazzmaster, it needed to be setup way higher, exactly like when the neck of the JM was tilted by shimming. Taking into account how many little tweaks the Marr Model has, I wouldn't be surprised if they routed the neck pocked so that the neck is slightly pre-tilted. So maybe shimming a MarrJag isn't neccessary.

Yup, the Marr neck pocket is carved so that a shim is unnecessary. Mine certainly doesn't appear to be shimmed, and I've barely needed to touch it since I got it two years ago. Best setup I've ever had experienced right out of the box. I did put an authentic Staytrem on it as Marr does with his, but didn't need to touch anything.

I did have the same experience when installing a Mastery on my Jazzmaster. It's got some pretty hefty shimming going on (relatively speaking) and there's a fair bit of daylight underneath the bottom of the bridge, but the resulting playability and tone is awesome.

[deviantkirby]

Happy that this is being talked about! I have a Johnny Marr Jaguar from the original run with a Mastery bridge. My tech and I just experimented with shimming it and the bridge had to be raised super high to compensate . So high in fact I would have to get new pickup screws to get them high enough. Plays like butter mind you! I was having issues with bends high up the neck.

[Webrocker]

Happy that this is being talked about! I have a Johnny Marr Jaguar from the original run with a Mastery bridge. My tech and I just experimented with shimming it and the bridge had to be raised super high to compensate . So high in fact I would have to get new pickup screws to get them high enough. Plays like butter mind you! I was having issues with bends high up the neck.

one of the key elements to get the best out of a mastery bridge is to get it as low as possible. the base should be as close to the body, inserting as much of the stem material as possible into the body, reason being that it's not designed to rock back and forth with the trem movement, but let the strings slide over the saddles. more material contacts with body, better sustain.
that's contrary to what you'd do with the stock bridge, where an angled neck plus raised bridge will give you enough friction over the saddles so that the bridge can rock with the trem movement and you'd have less string slippage and more sustain.
the mastery has no problems regarding string slippage and with the three saddle design enough 'pressure' from the pair of strings over each saddle, so it'll add sustain. even more so, if you can lower it as far as your action will allow. which in my tests got better when I *removed* the shims in the 'traditional' Jag and JMs I tested. With the Marr Jag lowering the Mastery isn't possible beyond one point without lowering the action beyond playable, which made me suspect that the neck pocket is routed differently to add all the 'traditional' benefits without the need for a shim. of course you can set up a mastery riding high, and it'll work just fine, it's just that you'll not get the total benefits it was designed for.
For me (and this is highly personal, so please take it with enough salt), a traditional bridge design worked better for the Marr Jag. Had the string spacing not been too close to the fretboard with the original bridge with mustang saddles, it would have been perfectly set up and playable out of the box, but b/c of the spacing, I ended up with a stay trem, and would otherwise use a stock bridge (with the slotted barrels to adjust the string spacing).

[deviantkirby]

@webrocker Thanks so much for chiming in! I've had the Mastery ever since I got the Marr in 2012. I've seen pictures of Marr Jag's with Masterys that sit really low like you describe. The only thing I can think of is I bought some Mastery thimbles a couple years ago and I wonder if they are too shallow? I will definitely be taking out the shims and see how that affects the action. I'm a jazz/fusion lead guitar player and I also play slide so my Jaguar is setup for big bends!!

[neils]

I have a 60's Lacquer JM and I installed the .5 degree Stew Mac shim. It is exactly right. With the stock or now a Stayrtem bridge it all worked out as planned and plays/tunes/intonates like a dream.

Neil

[joesnewmatch]

Very informative thread.

I wondered if I was going to need a shin before my Marr-guar arrived, but the break angle is great. The action isn't as low as some of my other guitars, but it still plays great.

With the 7.25" radius, I think you need a little bit of clearance for more effective bending high in the frets.

[deviantkirby]

Just a quick update. Took out the shims and was able to lower the bridge significantly. Seems as though I have a couple frets that need attention in the 15th-16th area that are causing me issues. Doris is going on 5 years with a ton of hours on her. Think it's time for a top to bottom setup and check up!!!