Parts Used:

8Bitdo RB8 - https://www.amazon.com/Retro-8Bitdo-Wireless-Blue...

Gamecube Joystick Replacement - https://www.amazon.com/Redesigned-REPLACEMENT-Joy...

And you know where to get an original OEM controller.... I STRONGLY urge you to start with a non-working controller. Something that, say, has a terrible condition joystick. There are a limited number of good controllers out there so don't take one out of the pool!

You'll need a small (jewlers size) phillips head screwdriver and a soldering iron (with desolder pump, solder and tweezers). If you don't have experience soldering, get a cheap kit and just practice.

Step 1: The Joysticks

Originally I just wanted to cram the 8bitdo controller (because of its bluetooth feature) into the OEM nintendo controller, but as I started taking things apart I realized this was a perfect chance to upgrade to the Gamecube replacement joystick (see description for link). It fits the OEM plastic casing, the 8bitdo joystick doesn't exactly fit the Nintendo plastic.

The three joysticks from left to right: 8bitdo rb8, OEM Nintendo, NEW Gamecube Joystick for N64 (replacement part).

Start by taking apart the gamecube joystick. Note that the plastic is glued/fused together around the edges. I had to break it to open it up.

If kept in tact this wire harness could be re-used to replace other parts.

Step 2: Re-wire the Joystick

Remove all the wires, resisters, chips everything, don't forger the capacitor on the back. All the highlighted pieces need to be removed. Just desolder them all, don't worry about damaging the pieces you don't need any of them. Try not to destroy the PCB though.

I had a 6-wire ribbon that I used, (stranded, 28 awg). I recommend a solid core, they are just easier to work with. Note the pins and coloring. Individual wires work too, I just like using ribbons.

Step 3: Take Apart the Controllers

Now its time to take apart the Nintendo and 8bitdo controllers. Both controllers have the same screw locations and they are easy to find: 2 in each of the 3 handles, two extra in the center body, and two smaller screws tucked inside the memory bay.

Keep the buttons, screws and keymats separated. You do NOT want to mix them up. Give the pieces a good wash (if they are dirty); I used an old toothbrush to clean them up. Give plenty of time to dry.

Step 4: Dismantle the OEM

Desolder the L R and Z buttons, two pads each noted in circles. I removed them at the board because the wires used by Nintendo are much sturdier than the 8bitdo wires.

Top/Front Mainboard of the Nintendo OEM controller (picture with the black chip, green body).

Back/Bottom of OEM Nintendo mainboard, with the same pins circled (picture with the brown board, and memory card slot).

Step 5: Solder to the New Board

Bottom/Back of the 8bitdo mainboard.

Do the same thing, Desolder the L, R and Z wires. Also remove the 6 wires lined up on the left. Those connect to the joystick potentiometers (high, common, low for each of the two).

Once you've removed the parts from the 8bitdo board, solder the OEM Nintendo parts back onto the board. Make sure to match up the wires in the correct order for the joystick. The L, R, Z order does not matter but if you get it wrong the case might be more difficult to put back together.

As you can see, I had trouble getting the ribbon wires on and burned the PCB a bit. Damaged some of the solder points/pads so I added a bit of hot glue to study up the whole set. DO NOT add hot glue until you have tested the joystick to work.

Step 6: Adjust the Casing

The 8bitdo mainboard has a slightly different shape than the OEM board, and additional pieces like the sync button on the back, USB port on the top and the battery.

Grind down the middle pieces; the wire port needs to be ground down, or cut to make room for the USB connection.

The purple controller was my first attempt, I used a hot glue gun to melt the plastic. It really is not pretty. That was before I realized I had a dremel in the garage. I used a hobby knife to cut off the excess melted plastic.

The green controller was my second attempt (both are in great shape, no dead bodies!).

FYI You need to take off more of the top than of the bottom.

Step 7: Put It All Back Together

Make sure you test before you put it together. I used the Nintendo Buttons, Keymats (silicone pads) and screws (duh) to go in the shell. The N plastic just feels better, and the buttons "click" better along with having a softer and more smooth/curved shape to them.

Note access to the bluetooth Sync button. Key feature here is that the expansion slot functions as a holder. It will lock a pack in place, but cannot transfer anything (no connection).