The stock mini-z motor mount holds the the motor around its parimeter. Shims are used to adjust the pinion gear mash. However, most aftermarket motor mount holds the motor with 2 screws to allow for pinion gear mash. Stock motor, the Kyosho X-speed motor, and some aftermarket motors does not come with threaded hole on the end of the motor. If you want to upgrade to an aftermarket motor mount, either get a motor that have threaded holes on the end, or drill and thread the motor.
Good news is it is relatively simple to drill the motor. Is not required to even open up the motor. Pretty much the only thing you might have to purchase is just the right size drill.
Drill - For the M2 X .4 screw that the motor use, the standard drill size is 1.6mm which is equivalent to 1/16" drill. However, for a stronger thread, a smaller drill size should be used. Too small a size drill makes it hard to start the tapping process though. I would say don't go below a #55 (.052") drill.
Tape - Need double sided tape and some regular tape.
Screw - M2 X .4 metric screw. Best to get the kind with a deep socket head that give a stable hold when you are threading the screw into the hole.
The easy way to drill the motor if you already have an empty motor case avaliable that is drilled already. Just put the empty motor case on the shaft of the motor you want to drill, and use the holes on the empty motor case as a guide to drill the blank motor.
Here is what you can do if you don't have an empty motor case.
Mark the centerline of the motor. Use a caliper to scribe a thin line or use a thin marker. This will help you drill an accurate hole.
Apply double sided tape to the motor. This will help hold the motor in place during drilling. The PN racing rim tape worked pretty good.
Tape drill bit so it is the same diameter as the hole in the motor mount. Set the tape 1 drill diameter back from the tip of the drill. The tape serves both function as a centering tool and as a drill stop to prevent the drill from going too deep into the motor and damaging the motor internals.
Align the motor on the motor mount. You can see the scribe line helps a lot in alignment.
Use the round hole side of the motor mount as a guide to drill. When starting the drill, carefully apply light pressure while making sure the motor has not moved in the mount until a dimple is created by the drill in the motor housing. Watch the break thru, and ease up on pressure also when it is breaking thru.
Use the M2 X .4 screw the tap a thread in the housing. Housing is soft enough that just the screw is enough to create the thread. Hold the motor close to you so you can apply strong pressure when screwing the screw in. If you don't apply enough pressure you may strip the first few thread trying to get the thread to start. Holding the motor in a vice may also help.
Once one side is done, rotate the motor 180 degrees, and screw the motor onto the mount with the one screw on the slotted hole side of the mount. With one screw on, align the motor and drill the other hole. This way, you are guaranteed that the holes will line up. If done properly, you can get a perfect drill or near perfect drill everytime.
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