Mating the motor to the transmission and mounting the motor in the engine bay was a time consuming and critical part of the conversion process. I learned a great deal in the doing of it and the solution I came up with seems to work well- I haven’t experienced any trouble with it. The front engine, front transmission layout with symmetrical motor mounts lends itself to relatively straightforward motor mounts. One interesting thing to note is the way the Miata drivetrain is laid out- there are no transmission mounts. The transmission is bolted through the bellhousing to the engine, and in the rear to the “power plant frame”- a long aluminum piece, C shaped in cross section- that connects the transmission to the differential. This very effectively supports any rotation of the engine and transmission in the plane that would bisect the car between the seats. It also provides a certain amount of rigidity to counteract the torque of the driveshaft on the differential, preventing that torque from acting on the chassis.
After removing the engine and transmission together, then splitting them apart I began to plan the motor mounts. This was aided by photos and drawing in shapes using Photoshop. At the time I hadn’t learned to use any CAD software.
Note how close the motor hangs just above the steering rack! The motor mount was made from some steel tube, some 1/4″ plate and a motor ring clamp from an EV conversion parts dealer. At this point I finished installing the adapter plate and hub, and assembled the new clutch. The adapter plate/hub was from Electro Auto. They had the drawings for the Miata adapter on file- aside from some discrepancy in number of bellhousing bolts the adapter system works and fit very nicely. The taper-lock hub adapter works very nicely and is easy to install and adjust. The flywheel was machined and Exedy stage II clutch installed.
From an empty engine bay, to a sturdily mounted motor! It was about at this point that I jumper-cabled the motor to a spare 12v battery and drove it up and down the driveway a bit. What a great feeling! And some toasty jumper-cables!