I bought some recycled 1/2" aluminum plate off Dr. Bill that had vulcanized rubber on one side to use for my motor adapter plate. I did some calculations and 1/2" aluminum is plenty thick for the stresses it will be seeing. I am also going to be using a couple pieces of 3/4" thick aluminum as a spacer to complete my adapter and put the motor where it needs to be with respect to the transmission.
I attached the drawings I made for the plate and the assembly.
I am going to be keeping my clutch. I would like to autocross this car just to raise some eyebrows so I want to be able to make quick shifts if needed. I had the flywheel lightened & ring gear removed by a machine shop. I wish I had weighed it before I took it in, but too late now.
I wanted to maintain the pilot bearing that the end of the transmission shaft slides into to ensure the transmission and motor are aligned properly. The problem is the pilot diameter in the Warp 9 motor is not the same as the pilot on the BMW crankshaft. I found a bearing with an OD the same as the Warp pilot diameter, but it didn't have the same ID as the transmission shaft. I found a some tubing that had the same ID as the transmission shaft and an OD that would fit in the bearing. In the end it all fit very tight and there was no slop.
I had my motor coupler machined out of 4130 at a local machine shop. The 1/4" keyway should be sufficient with a 1/4-20 set screw to hold it all together. I also made a spacer to position the coupler the correct distance from the bearing on the electric motor. I found that a coupler for 1" copper pipe has a 1.125" ID which matches the motor shaft. This setup allows the clutch force (only ~400lb) to be transferred to the drive end bearing instead of the shaft. The clutch will hold the coupler in position from the other side, so all the set screw does is keeps the keyway from sliding out.
I decided I wanted to keep the existing motor mount points and mounts that BMW used. To do this I made a bracket that bolts onto the front of the motor at one end and bolts to the motor x transmission adapter plate at the other end. This ended up being a more complex project than I anticipated, but it should work out well. I did not want my motor to be rigidly mounted to the frame of the car. By keeping the motor mounts it is somewhat isolated, just like the ICE was. I also took this route because I don't completely trust the band clamps that others use to hold the motor in place.
One issue I ran into is the placement of the motor. My goal was to have the motor positioned so that the transmission was in the same place and at the same angle as with the ICE. When in this position the Warp9 blows right through the power steering rack and the subframe/crossmember. The interference is ~80mm (3"). The power steering rack sat higher than the crossmember so I decided to drop it down ~.5" to put it at the same height. This would allow me to position the motor closer to where I wanted it, but it would still be at a slight angle. After test fitting the motor I do not think the angle difference is going to be an issue with the u-joints on either side of the driveshaft. To drop the power steering rack i cut up the brackets, bent them down and then welded filler plates back in. I don't even think it will affect my alignment, but I'll check before I get the car on the road.
The vacuum pump is for the power brake booster. I'm not sure if this pump will be sufficient, but it was 10x cheaper than other pumps out there and thought it would be worth experimenting with. I may run 2 if it can't keep vacuum built up for the brakes.
Right now I am waiting on some parts and trying to figure out what batteries I am going to use. I wanted to use LiFePO4 but they are not going to fit into the budget right now so AGM will need to work. I did not want to worry about adding water to flooded batteries, and need to mount a few on their side. I also don't want to worry about high discharge rates of 5C+ for short periods.
I plan on putting 4 batteries under the car where the gas tank was, 5 or 6 in the trunk and 3 or 4 in the engine bay.