Gearing?
 

I am running a slash 4x4 with 3s lipo. I have put a motor fan and the speed control fan. It still overheats. I was told if I lowered the teeth on the pinion gear it wouldn't overheat. I currently have a 13 tooth pinion and a 54 tooth spur gear. Also how would this effect acceleration and speed?

How hot have you had it? Do you have a temp gauge? You said it still overheats ,you might have ruined the rotor runing it hot to many times .

Another guy at the track had a temp gun it read 160. The truck would shut down from a couple seconds to a minute. It only took about 10 minutes to reach this temp. With the fans I was able to get about 25 minutes before it started to get hot enough to shut down.

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also check your drive train for resistance, just remove the pinion and try to roll it. it should roll nice and free with no friction, if you feel it does not have a problem with the drive train then defenately lower your pinion gear. Also alot will have to do with the track surface and your driving habits. let us know how it turns out.