One area I found that needed improvement was the motor cooling. There is an internal fan which does a decent job, but on longer commutes like mine the temperature of the motor just continues to rise. On really hot days I found the motor would cut out a little from time-to-time. My theory is this is the springs that hold the brushes down becoming too hot and allowing the brushes to float briefly.
My plan is to install four small fans directly above each set of brushes that turn on when the motor heats up using a thermostat. The thermostat is basically a temperature driven switch that will trigger a relay to turn on the fans. I selected 40C or 105F as the turn on. This will keep it from turning on during short trips but will ensure it starts cooling as soon as possible.
Here are the fans I used. They are 2" fans that do 20 CFM and draw .25 amps.
Here is one of the mounted fans and the thermostat. I made a bracket that attaches to the old temperature sensor and the thermostat bolts to the bracket.
When I manually enable the system I can feel a good breeze coming out the back the motor so that's a good sign. We'll see what happens after I get it back on the road.