I just finished mounting the Grainger 12 volt motor in my fresh air heater.
To make the shaft adapter, I used a piece of copper tubing with an outside diameter of 5/16" and an inside diameter of 1/4". The copper tubing was about one inch long. I had to sand down the outside of the tubing a bit to get it to slide into the fan shaft hole. I also had to run a 1/4" drill bit down the inside of the tubing to get it over the new motor shaft.
Only other thing I did was to drill through the tubing where the fan set screw goes so the set screw would bottom out on the motor shaft and keep everything in place.
I have always had trouble trying to run the six-volt motor with the resister. Just easier to change the notor to twelve volt and eliminate the resistor.
I wonder if I ran the resistor in line to my horn if it would make it sound better?
