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Now that the transmission modifications are mostly sorted out I have to get on to figuring out how to couple the motor to the transmission.

In my old setup, there was a coupler attached with set screws and a key to the motor shaft. This seems to have been ok but the general consensus seems to be that this will fail under higher power setups. Since I plan to hopefully make my car a little more peppy, this is a little of a worry so I am hoping to switch to a more durable taperlock setup.

QD Taperlocks work by using a tapered bushing that has a cut in it. The bushing goes on the shaft of the motor and then goes in a matching tapered hole (on the coupler). There are bolts that pull the bushing into the hole and cause it to clamp down on the shaft of the motor. They also can have a keyway cut in them. You can get a tremendous amount of clamping force with them and they tend to clamp all around the shaft instead of just pushing on one or two points like a set screw coupler.

I would have loved to have ordered one from Electro Automotive but they seem to be unresponsive these days. They don’t already have a pattern for my transmission so I would have had to send the transmission to them. I’m a little scared to do this since they don’t seem to enthusiastic about making adapters anymore. So, my plan is to make the coupler myself (or have a local machinist do it for me).

The easiest way to start is to simply cut the end off a crankshaft and modify that. Unfortunately, the flange on the end of the crank is rather small and wouldn’t really supply enough material to install a large enough taperlock bushing.

I designed a coupler from scratch in Rhino but the problem is that they bolt circle for the taperlock bushing interferes with the bolt circle for the flywheel. To get them to not interfere I had to go up to an extremely large bushing (which has the advantage of being able to handle more than 900 ft-lbs of torque). This makes the coupler get very large which in turn pushes the flywheel farther away from the motor which means that the whole motor/transmission gets a little longer.

It seems like the best solution is going to be to make a brand new flywheel that accepts my exedy twin plate clutch and a taperlock bushing. I drew up another design and it definitely makes for a much neater and simpler design. It allows me to get rid of the ring gear easily and it makes the whole assembly pretty light. My current design should way a little bit over 7 lbs when machined out of steel. Now I just have to find someone to make it for me because I think it’s a little too much for our lathe.

Tags: adapter, cnc

This entry was posted on Tuesday, November 27th, 2007 at 10:04 pm and is filed under EV. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.