Ready to go brushless? Here we go.
First thing's first, assemble all of the parts and tools necessary. You'll need a GWS 400 gearbox frame, not the entire gearbox, just the plastic frame. I ordered a box of them from All E RC, they cost $1.25 each. Like I said, this is an inexpensive project. If you happen to have an old GWS gearbox laying around, you can use that too. Just remove the spur gear and shaft, and push the bearings out of the frame. You'll also need a Dremel tool with a cutoff wheel, a short (2 or 3 inches) scrap of .188" carbon fiber tube which just so happens to be the same tubing I use for the wing spars in my Evos, a drill bit the same size as your carbon tube, 3 nylon ties to attach your finished mount to your plane, some thin CA, and a hobby knife or two with different shaped blades.
First, we need to ream out the gear shaft hole to fit the carbon rod that we're going to use to reinforce the mount and create a third tie down point to make the motor more secure. I don't recommend using a drill to turn the bit since the plastic will melt if you're not extremely careful. I just twist the bit through with a pair of pliers.
When you've finished enlarging the hole, test fit your carbon tube. The fit should be reasonably tight, but if it can wiggle around a bit don't worry. We'll secure the tube in the hole with a dab of CA later.
Next we'll cut off three sides of the stick mount portion of the gearbox frame. Try not to cut into the top portion of the stick mount, leave a nice flat portion on the bottom of the mount as this will be the platform the entire mount sits on when we zip tie it to the Mugi Evo.
This is what it should look like when you're done, no more stick mount, just a nice flat platform. Don't worry if it's a little rough, the sharp edges will just help to keep the mount from sliding around.
Next we need to make a place for the center nylon tie to sit. If you hold one of your nylon ties around the mount, centered on the large section that's designed to hold the motor, you can easily make a little mark on either side of it with the blade of a hobby knife. When properly modified, these little bumps make a keen retainer for our nylon ties.
Then carefully grind out the material between the marks with the Dremel so that the nylon tie will sit flush like this. Try not to cut too deeply, or you may weaken the mount.
Mount the motor to the plastic mount facing rearward, like this. Think about which direction you want your motor wires to face before installing the screws, and don't overtighten the screws or you'll crack the plastic mounting ears.
Now place the carbon tube into the hole that we drilled earlier. Position the carbon tube so that it hangs just a bit onto the rear portion of the motor can. Make sure that it can't rub on the rotor however, or you'll likely let the magic smoke out of your powerplant in very short order.
This is what your mount should look like at this point with the motor attached and the carbon rod properly positioned.
Drop a little thin CA onto both ends of the carbon tube, allowing it to wick in between the carbon tube and the plastic mount. Use extreme caution not to allow any CA to get into the motor.
If you use a motor like this one with a long, threaded shaft, you'll likely want to cut the shaft off and use a set screw or collet type prop adapter instead of mounting the prop directly. A long shaft like this would likely get bent on the first landing with a Mugi Evo, so cut it off as short as possible while still leaving enough material to mount your prop adapter securely.
Well, here it is, the completed mount. Now let's take a moment or two to blow/wipe off the dust and shavings, then we'll attach our brushless outrunner to our Mugi Evo.
Start by making a small mark on the centerline of the top doubler, approximately where you want the front of your motor mount to be. I prefer to use a pencil since the marks will virtually disappear if you're not looking for them.
Draw a faint line from the center of the rear of the fuselage, to the mark that you just made. This way we'll have a definite centerline with which to align our motor mount.
Using the tip of an Exacto knife, poke a small hole next to the carbon rod at each end of the mount, and next to the large portion of the mount in line with the grooves that we ground earlier. When you're certain that all six holes are where they need to be, poke the holes all the way through the airframe and enlarge them with a small screwdriver just enough so that you can easily pass your nylon ties through.
Next we'll secure the motor and mount to the plane. I start by threading the rearmost zip tie around the carbon rod of the mount, then through the holes in the coroplast. Don't pull this tie tight yet however, since we want to tighten the front tie first to get the proper thrust angle. If you use a pair of pliers and a screwdriver like this, you can ratchet your zip ties down extremely tight, just be careful that you don't suck them right through the coroplast!
And here's the finished installation. If you look carefully, you can see the third nylon tie peeking out from under the motor. By installing the carbon tube, and using it to secure the mount to the plane, we can now switch motors simply by removing the screws. No zip tie cutting involved. All that's left is to install the 3mm prop adapter and prop and hook up the wiring.
Here's a view from the underside. When properly tightened, the nylon ties shouldn't allow anything to move around, but they shouldn't be threatening to pull through the plastic either.