for gearing, most likely you wont get an all around ratio. what motor are you using because you might be able to convert torque from your motor into speed. but if you are at 18/74, to get more speed get a 19 or 20 tooth pinion. for more bashing torque, a 16 or 17 tooth should do it. just watch your motor temp. cause if you go too high or too low, you can easily fry your motor and that leads, if you dont catch it, to a fried speed control. i mean deep fried. basically if you divide the pinion (your 18) and the spur (your 74), you get your gear ratio. the closure this ration is to one, the more speed you will get. yours right now is 0.2432. with a 19 tooth pinion, it would be 0.256756 making your car or truck or whatever you have a bit faster, but keep in mind that you loose torque too. but also keep in mind that if you are going to be bashing with a friend, slip on a 17 tooth for more power, but if your racing and need more top end speed, slip on a 19 or higher tooth, depending if the motor gets too hot.

ask if you have anymore questions
-ted