I took some vacation time, so I finally accomplished the install. It turned out as good as I could have hoped. Please pardon the less than stellar photography I was using my Android tablet which isn't the best camera.

I did quite a bit of studying on Sunday before diving in.

Once I got under the hood, I found that there was ample room for the GK Circuit Board, but it is very busy under the pick guard. I decided to put the GK volume on the lower cut away as far forward as possible to keep me from punching it on those big Pete Townshend chords. I also decided to forgo the bank buttons or switch, and the Output selector. I can easily navigate banks and patches with the foot pedals on the GR55, and if you don't plug anything into the output selector header plug, the board thinks it is in the "Mix" position which is fine for me since I'll be running the JTV signal through the HD500. Here's some pics of my planning layout:

No matter how I approached it I couldn't find a way of adding the 13 pin while keeping both the VDI and the 1/4 inch. The 13 pin would have run into Variax Circuit board if I tried routing a location on the VDI side of the OEM jacks, and it would have been too low on the body if I'd put it on the 1/4 side, which would have had it pointing almost straight down.

I figured the only way was to replace the 1/4 inch with the 13 pin, which is fine for me because I can count the times I've used the 1/4 inch on no hands.

The next problem was to figure out how to do this. The OEM injection molded plastic jack plate is sculpted to the point that I would have very likely destroyed it in trying to alter it enough to be able to mount the 13 pin on it, so I took an old pick guard that I had from a Variax 300 that I had long since sold, and I fashioned my connector plate from it. It wasn't too difficult and I had enough material to make several tries if the first one didn't work out. Luckily the first attempt was fine so about an hour later I had this:

I was never all that fond of the trap door on the OEM model anyway.  I metered the 1/4 inch jack assembly, and though there are some capacitors, ferrites, and switching on the jack, I was able to determine that when the jack is empty, it is essentially as if the jack isn't there. So, I unsoldered the header from the jack assembly and taped it up.

Now for the scary part; Drilling and Wood Removal

I used a standard Dremel Tool that I picked up at Lowes and a saber action rotary saw bit to route out the compartment for the GK Volume, and to square the jack plate cavity so the 13 pin would fit:

Oh and I also taped up that little ground wire you see there that went to the 1/4 jack.

After testing to see that the jacks and the GK Volume pot would fit into place, I moved on to mounting the GK Pickup.

The GK Kit instructions say to mount the pickup as close as possible to the bridge pieces, so I masked and carefully marked the area. You may notice that I also trim the original upper mounting tab of the pickup, and redrill it. I don't know why Roland puts this extra 1/4 inch or more on it, unless it is the same piece as on the external GK where the wire exits off that end, and they don't want to retool the factory, so they use the same piece on the kit as well.

I decided to drill the cable hole first, so that I could lay the pickup flat on the top to use as a template for drilling the initial pickup mounting holes for accuracy. I determined that I would have to go at an angle to exit in the trem cavity for easy routing of the cable through the same hole as the Variax bridge cables into the circuit board cavity.

Here are 2 pics showing the entry and exit wound, and the angle of the entry:

If you're thinking that the header plug won't fit through that hole, you are correct. I have experience with this type of plug from my work as a radio technician. A straight pin or needle will act as  a pin releaser, so I wrote down the color code and removed the pins. All the pins grouped together was still too large for the hole when taped up, so I folded 1/2 of them back on them selves to reduce the girth when taped, and was then able to work them through. Pic:

Now to finish the pickup mounting. I found these nifty little inserts in the specialty fasteners in the drawer indexes at Lowes under Furniture Fasteners.

Unfortunately, I had to go to a different hardware store to find 6-32 thread machine screws with an allen head. I used an allen because all the pan head screws I could find were too wide for the mouting bracket and would bind against the metal cover of the pickup. I used electrical tape on the bits to control the depth of the drilling, and progressively stepped up from the eigth inch hole in the bracket to a size just under the thread width of the inserts. A set of calipers is very handy for this type of measurement. I would prefer a drill press for this, but I took my time and was able to freehand it. Here are several pics for this step:

As you can see, the inserts are recessed just below the surface of the top, which gives a resting place for the springs. Hint, the springs provided are too long for most applications, so take some side cutters and trim about 1/4 inch off each spring. This will also keep them from shooting across the room when you try to install them.

Ready to assemble! I have a staple gun that is made for captivating cable, so I put a couple under the springs in the trem cavity to keep the GK pickup cable from moving around any more than necessary, but loose enough to have some play if I need it.

Here's the electronics cavity with the board installed, and the newly fabricated jack plate installed.

A quick trip to a local music store for a nearly perfect match chrome knob, about an hour to set up, and intonate the guitar, and then set up the parameters of the GK installation in the GR55, and the job was done. Start time approximately 7:30 a.m. finished at about 2:30 p.m. plus about 2 hours of study and planning the day before.

If you've made it this far, thanks for hanging in there.  This may be more than a lot of folks would want to take on, but if you are good with your hands, take your time, and maybe read the book "Zen And The Art Of Motorcycle Maintenance" before getting started, the payoff at the end is too much fun!!!

Good Luck!

Mark