February 25, 2002

The next challenge is how to connect the electric motors to the differentials, so that the power can get to the wheels.

To do this we are going to have to design, and have fabricated, a drive shaft that can connect the female metric spline of the motor ...

motor female spline
to the flat plate of the differential. differential to drive shaft plate

The simplest connection would be the appropriate spline with a flat plate welded on its base. To avoid binding, we would need to build our motor and differential mounts to a very fine tolerance. In addition, we would have to make sure the motor and differential did not move in relationship to each other under our torque loads.

A better solution is to plan for a little slop and use a Constant Velocity (CV) joint to allow it. CV joints are usually used between the differential and the wheel, to allow torque to be transmitted to the wheel while the suspension is moving. The movements we expect between motor and differential is tiny compared to a wheel going over a bump.

We draw up a rough design using a Formula Ford CV joint.
motor to diff diagram rough
We contact Taylor Race Engineering for advice and assistance in getting our drive shaft built. Not only is Taylor Race Engineering a well regarded racing driveline specialist, but Craig Taylor advised and drove for a college electric vehicle race team. His practical experience and willingness to share that knowledge make him a great resource.
After a few emails back and forth of designs, we agreed on a final design and ordered 3 drive shafts. One for each motor and a spare. Since it is an unusual spline size, it will be four weeks before we will receive the part and we will need to ship them a motor to assure a perfect fit.
drive shaft final


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