Sunday, September 20, 2009

Connecting the motor to the transmission

I've been very remiss about updating this blog, so I'm going to do my best to "catch up" a bit. It might take a few entries to do it, but if I don't do it now it might never get done.

Attaching the AC24LS motor to the Saturn transmission

The motor-transmission adapter that comes with the ElectroAuto kit is quite impressive.  Very professional machining job, and I especially like the elegance and strength of the flywheel adapter which uses a taperlock design. The flywheel adapter is a special 2-piece unit that converts the keyed output shaft of the AC24 motor to a flange with the proper bolt pattern so that the Saturn flywheel can be attached to it, the same way it attached to the ICE output shaft.  Sorry to say I have no pictures of this, though. I was so excited to actually be putting something together that I completely forgot about documenting it!  And at this point I'm not going to take it apart just to take pictures. You'll have to take my word for it. (or look at other websites where they actually remembered to take pictures)

Anyway, after following the directions and installing the flywheel adapter so that the "magic distance" is correct (the magic distance is a measure of the location of the flywheel relative to the end of the motor output shaft and is important so that the clutch will work properly), a friend and I muscled the transmission onto the adapter and bolted it together.

A little background here.... the front face of the AC24, where the output shaft exits, has four bolt holes in it which serve to allow the motor to be attached to whatever it is powering, whether it be a conveyor belt, lathe, or electric car. So the motor can be installed in any 1 of 4 orientations.  A typical DC motor is cylindrical in shape and so doesn't really have a top or bottom side to worry about during installation.  The AC24 motor, on the other hand, has cooling fins which basically turn it into a rectangular prism, with a definite top, bottom, left, and right side. One side, which I shall call the "top," has a large electrical box on it where the main power cabling is attached. Looking from the back face with the electrical box on top, the right side has 2 grooves cast into the casing which are designed to accept the head of a 10-mm hex bolt. These are how the motor is supposed to be mounted. (I actually have a picture of this! Though as you can see the motor has been turned 90 degrees - more on that later!)

The other two sides are basically blank, though supposedly one of those sides can have a lifting eye installed (mine didn't).

Ok, where was I? Oh yeah, the four mounting positions. So, because of the 4 bolt holes in the front face, the "top" (with the electrical box) can be mounted either in the up position, right (toward the front bumper), down, or left (toward the firewall). My initial thought was that it would be easiest to mount the motor with the mounting side in the up position (electrical box to the firewall), and construct a simple bracket made of angle iron to secure the motor to the existing upper engine mount. It would require the least amount of metal (less weight) and it would be easy to access the mounting bolts in case I needed to pull the motor out. Too bad I didn't think about the driveshaft. As soon as the transmission was attached I immediately saw the problem. The driveshaft to the passenger side wheel runs alongside the motor, and very close to it. So close, in fact, that the electrical box will interfere with it. I have a picture which sort of shows where the driveshaft exits the transmission, but it's hard to see from this angle that it will interfere. Trust me, it does. Bummer. Ok, plan B.

If I rotate the motor 90 degrees clockwise (when viewed from the back face) there will be a "blank" side toward the firewall, which is good for the driveshaft, but now the mounting side is toward the bumper, which makes a motor mount design tricky. More complicated, more metal required, and worst of all the electrical box is now "up", which means it is unlikely that I'll be able to install components above the motor. Not a good Plan B.

If I rotate the motor another 90 degrees clockwise, another "blank" side is toward the firewall (good again) and the electrical box is toward the bumper (good, since it frees up room above the motor), but the mounting side is now "down." This basically rules out using the upper engine mount, but it was possible that I could instead use the lower engine mount. It seemed the only way to go, so again with the help of my friend we disassembled the motor from the transmission and re-installed it in the new orientation. Yep, no pictures of the assembly process, but here's a picture of the assembly in the engine compartment.
Next, the motor and transmission mounts.....

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