Mark Dodrill wrote: > I'm pretty sure I'm pushing the thermal limits of the motor as it is. I > live in an area with lots of hills, so even keeping the motor speed up to > keep the cooling fan working well isn't enough. > > Perhaps someone can tell me what temp levels are okay, and what is too > high--case temp, and brush temp is about all I can measure given how the > motor is installed.
When I asked Otmar about sensing motor temperatures, I found out that unless you have a dragster (such as I have a lo-perf 96V street car), the case temperature is the way to go, and a lot less complex than trying to measure brush temperatures. Otmar indicated a case temperature of 150-degF is as high as the motor should go. The ADC 8" motor, and probably the 6.7" motor as well, has an open threaded hole in the case. We went to the VW shop, purchased a water temperature coolant sensor, replaced the thermistor in the sensor with a different one from Allied Electronics, and last but not least machined up a little brass adapter to fit the VW sensor into the ADC hole. We then hooked this up to the Rabbit's stock temperature gauge wires. We had to make an addition, though, that I wasn't planning on, which was to add 15.4 ohms of resistance to the circuit, as the current in the temp gauge circuit was apparently overpowering the thermistor. So now I have a temp gauge reading just at the bottom of the red band when the case temperature hits about 150-degF. If your motor gets real hot, like you can't hold your hand on it, you need to get something done about it (fan)! There is probably an internal switch in the motor that you can use to turn on a light on the dash, but I don't know what temp this triggers, but it's most likely signifiicantly above 150-degF. Chuck Hursch Larkspur, CA www.geocities.com/nbeaa
