The first part to go on the motor is the taper lock bush. This piece has a slight taper, and as you bolt it together with the hub, the taper provides a clamping force that grips the motor shaft. This is one of the most secure ways to mount a hub to a shaft. I used a dial indicator to keep the face of the hub square to the motor shaft, as I tightened the mounting bolts (marked 1, 2, and 3 in the photo). Any error here will cause the flywheel to wobble and the vibration will be annoying and cause excessive wear in the drive train. I was able to get the wobble down to 0.003” (75 microns), and run out down to 0.002” (50 microns).
The flywheel is bolted to the hub.
The clutch is centered on the flywheel with a special alignment tool.
Then the pressure plate is added. The clutch is squeezed between the flywheel and pressure plate, and transmits power from the motor to the transmission. When the clutch pedal is pressed, the pressure plate is pulled away from the clutch disk and the motor and transmission are de-coupled, making it easier to change gears.