I'll get a better pic tomorrow. Basically a small wheel is glued to the pin gear on the motor and that is against the a wheel which makes it move.
All the electronics were given to me but that set up could cost about $150 - $200
I am currently waiting to buy PVC pipe for the actual track. Once i have that it'll be complete. Its an awesome set up just one downside.. The motor makes a ringing noise. Working on finding a slower/quieter motor. I have the gas and reverse set to the steering for more control and it runs a little slower