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

The pinion is the little gear that goes on the electric motor (between 13 and 20 teeth, usually). The spur is the gear that the pinion meshes with (between 82 and 90 teeth). Gear ratio is probably referring to the ratio of the pinion to the spur, if you have an 18 tooth pinion and an 82 tooth spur, then 82 divided by 18 is 4.555, meaning that the spur gear turns once for every 4.55 turns of the pinion gear. The final drive ratio is how many times the wheels turn for each turn of the motor. If you go to associated's site, they'll have a list of transmission ratios, find the one for your truck and combine it with your spur/pinion combination to find your final drive ratio.

A less scientific (read: math intensive) way to find your final drive ratio is to put a mark on the side of one of your tires, and a mark on the side of the pinion. Roll the truck on the ground until the tires turn once, and count how many times the pinion turned.
Brian

thanks a lot, now it makes a lot more sense

Check out the back pages of RC Driver Magazine. They always have section sponsored by Tamiya with RC Terms and definitions.
Also RC 101 on this site.
Dan