Well there is your problem, the LRP X12 motors run very hot as they are horribly inefficient. A local guy switched out a LRP X12 13.5 for a Tekin Redline 13.5, same car, same gearing and the motor temp went from 160 degrees to 110 degrees instantly. My Tekin 13.5 never gets above 110 degrees, normally hovers around 100 degrees.

The other key to gearing is whether or not you are doing timing in the ESC. In other words without comparing ESC/motor timing settings it's impossible to compare gearing apples to apples.

My setup:

RC10T4.1 Factory
Tekin RS / Tekin Redline 13.5
Thunder Power Pro Race 50C
78 spur / 20 pinion
Tacoma RC Raceway (80x40 indoor tight clay track)

Here is my Tekin ESC setup sheet with all the timing details. I've got great low end torque and punch in the tight infield and dang near unlimited top end on the straight away.

http://www.amoney.org/rc/AnthonyL_Te...11-11-2010.pdf