We've been kind of dead in the water here, waiting for Dave the Machinist to finish with the coupler. Got a text from Robert today to come over and take a look. You'll recall this piece started life as a five inch interference coupler from EV West. Now it's been completely worked over for best fit on my Porsche EV.
The front has been recessed, drilled and tapped for the flange with the clutch spline that fits the drive shaft. The rear has been opened up to shrink fit the main shaft of the Siemens motor. Dave tells me it is 0.001" undersized so it, too will grip after it cools.
The flange is such a perfect fit and as it sits in the recess of the coupler, it will provide an extra constraint to prevent run-out under load.
Dave suggested one more modification to keep everything in place. The spline length in the coupler is about twice what will engage with the splined motor shaft, so Dave is going to mill a shoulder and washer to run a bolt into the threads in the shaft. We'll cut off the pilot shaft down to the splines on the driveshaft since it doesn't need to spin in neutral. That's one more level of security for this critical link in the drive line. It also allows the motor to be located as far back as possible. Dave says he can get that done by the end of the week, so I'm looking forward to a flurry of activity as we get the motor and accessories mounted in the car.