After finding a local retailer who carries and special order Hub City parts, I found myself the proud owner of two of them (one as a spare). Here is one, in person:
It will go onto the motor shaft. Here it is, next to the shaft, for scale:
Here is a test fitting on the shaft - it fits *very* well - it takes a fair amount of steady force to remove it after sliding it on gently:
The plan is to find a local machine shop who can turn this into a taperlock hub. Just as in the Electro Auto kit, the idea behind a taperlock is to have a tapered hub that fits into a conical opening in a larger plate, and then the compression of the two with 5 screws also compresses the hub around the shaft. It is going to be tricky with the splined hub, since the splines will tend to resist compression. Here is a first pass drawing of how the hub will be modified:
I need to think about it some more - specifically:
- Will the two cuts allow the hub to compress sufficiently against the splines?
- Should the cuts be partially through the front of the hub (as shown), or through the back of the hub (with the uncut part machined smaller yet), or would a single cut yield better results?
One other option rather than turning the hub into a taperlock is to tap a center hole in the shaft, and then use a center bolt on a machined plate to keep the hub in place. The drawbacks are that any torque opposite the thread direction will tend to make the bolt want to come out. It is possible that the splines will prevent this (especially if the machined plate is also bolted directly to the hub, in addition to the shaft). But the possibility concerns me, since with regen braking, torque is applied in both CW and CCW directions on the flywheel.