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Designs for the driver's side engine mounting frame are now done after two month hiatus. Have built in a mix of steel and 3D printed parts to confirm fit. Current plan for the offside front mount is to bolt a clamp around the subframe to avoid having to weld anything on, finalising the design for that this week then will get all the parts laser cut.

Given the constraints of the existing subframe and motor mount positions, the i3 motor only just fits, but it does fit.

Will post the CAD files on here once I've built the mounts and confirmed fit.

To whom i should give my arm and a leg to get that CAD file from roadster subframe?

https://roadster-ev.blogspot.com/2016/0 ... embly.html

This guy I assume

That's the model I'm using.

Started welding the motor mounting frames this weekend. The main crossbar that picks up the two existing rear engine mounts is complete, and the driver's side frame that picks up the front engine mount and bolts to the right hand side of the i3 drive unit is almost done. Just a couple of corner plates to add for reinforcement, then onto the offside frame.

Have ordered a couple of rear wheel bearings so will then fit those and get the Smart's CV outer sockets in place in order to size up the CV axles and see what the options might be for connecting to the i3 CV outer sockets.

Offside frame done and everything fits reasonably well, though some of the bolts are a bit tight bringing it all together. Going to make a few tweaks to the CAD a mm here and there to improve the fit in case anyone else decides to build one.

Removed the skateboard that the drive unit's been sitting on so it's fully supported by the motor mounts and took a few photos. Position seems good and the mounts are supporting the weight well, while allowing some movement via the polymer bushings.

Just the offside front clamp left to do now.

Offside front subframe clamp now complete and motor fully supported. The tube coming off the motor mount ended up 15mm lower than expected so had to modify the top half of the mount to move the bushing carrier down. The base of the mount is also a bit close to the subframe seam.

Have since realised that the design can be improved to make it easier to fit/change bushings so will build another top half from scratch, with the bushing carrier 15mm lower and another 1mm of clearance between the bottom of the mount and the subframe seam. Planning to use a custom 3D printed TPU bushing (half of a test printed one is currently in the lower half of the bushing carrier).

The current top half of the clamp is good enough to support the motor for test fitting to the car, and also for measuring up the CV axles, which are next on the list.

Made good progress on the CV axles this week. Have fully dismantled and cleaned the outer Roadster CV joints, and the inner CV joints on the BMW i3 axles. The BMW end of the axles looks fairly straightforward with a set of 32 splines, but a potential issue is that the inner race on the Roadster CV joints appears to be part of the axle, rather than a separate piece that slides over a set of splines on the axle. A few images below.

Roadster CV axle end and a dummy wooden axle with a 3D printed inner race (I'm using a pair of wooden axles installed in the CV joints to get the lengths set up correctly): The Roadster's outer CV joint, with wooden axle installed: BMW i3 inner CV joint: The plan is to use some collars to hold the BMW i3 inner races on the other ends of the wooden driveshafts, for the inner CV joints. Will then line up the balls on the inner CV joints with the existing wear patterns throughout their movement range, and also check there's enough play to slide the axles into the inner CV joints in order to remove the outer joints from the wheel bearing. Can then send the two wooden axles off along with the original metal ones to have a custom pair machined.

I'm going to speak to some driveshaft specialists to see what they think the best solution is for incorporating the Roadster's inner race onto the shaft end. I'm guessing the options will be:
1. Cut the Roadster's shafts off around 30mm in from the inner race then externally spline the shaft stub and attach to the new CV axles using a splined collar.
2. Cut the Roadster's inner races off, drill them out and internally spline so they can slide over a splined end on a new CV axle (potentially not strong enough).
3. Find a different outer CV joint that has a splined inner race and a housing that either fits the Roadster's wheel bearing and ABS ring, or can be machined to fit (no idea what range of options exist here or how to check them).
4. Start with a large piece of steel and machine the Roadster's inner races onto the outer ends of the CV axles (assuming prohibitively expensive).

Ideas welcome!