i'm 13 and i just got an electric powered T4 (this was my first r/c car) and i am trying to figure out what a couple terms are and what the part does for the car, they are pinion, spur, final drive ratio, and gear ratio

thx,
alex

pinion is small gear attached to motor

Spur is bigger gear attached to transmision, pinion and spur work together to make car/truck go.

gear ratio is number of teeth on spur gear devided by number of teeth on pinion gear like 70/17=4.12 now 4.12 in your gear ratio

final drive ratio is the gear ratio times trany ratio like this 4.12(gear ratio) * 2.5(trans ratio)this trans ratio is diffrent for each car/truck so 4.12*2.5=10.30(fianl drive ratio)

hope this helps

Check out RC 101 in this forum. Great information for the begining racer!
Also, check out RC Driver Magazine. They have an informative article in each issue on RC Terms and technical information.