This has been a hot summer and even though the Boxster is a convertible, I DO want air conditioning. Plus I didn’t really want to mess with getting the existing air conditioning system professionally discharged. So, I’ve been working on a scheme that will let me keep the existing compressor and drive it off of the tail shaft of the main drive motor. In order to do that, I needed a way to mount a pulley to the tail shaft that matches the belt type of the pulley on the compressor. I tried finding something off the shelf, but didn’t have much luck. It is a six rib flat belt. However, I noticed that the water pump (on the engine that I removed) has a nice pulley on it that mounts using a simple three bolt hub. So, I decided to fabricate a hub that would bolt to the pulley and fit my tail shaft. It’s a simple part, except for the keyway. In order avoid buying a broach to cut the keyway (they are $80, and I would only use it once), I found a steel chain sprocket from McMaster Carr that already has the proper bore size and keyway. Then I cut off the sprocket teeth and machined it down so that it was thin enough to fit inside the pulley. I left a little alignment shoulder to make sure it mounted concentric. Drill three holes and it’s ready to bolt together.
I also wanted to start planning my battery placement. So, in order to visualize the cell placement, I laser cut a plastic box that has the same dimensions as my cells (ThunderSky LPF160’s). I used this online box maker to make the pattern. This should let me safely test fit different locations for cells without having to worry about shorting something out.