More speed

[Fiftygrit]

If I want more speed out of my truck, which gear is the best to change, or both of them, the small drive gear or the larger driven gear, I want to do a little more bashing, thanks. sorry I should ha counted them to see what the ratio is now.

[greene7717]

A larger pinion gear (the one thats attached to the motor shaft) will give you more speed but the trade off is lowering torque and increasing the wear and tear on the motor. Another option is upgrading to a lipo battery or a new motor depending on how much more speed you want.

[Olle P]

Changing the gearing will do little. At best you get a bit more speed, at worst you just get a warmer motor. Depends on how much load there is on the motor with your current gearing.
You can try to first run with your current setup. Take note of speed and motor temperature.
Then change to a pinion ~10% larger, and run a bit with it. See if the speed goes up and make sure the motor doesn't overheat.

Speed is primarily a function of motor power. To get more speed the motor needs to deliver more power. This can be done by increasing the voltage and/or using a motor able to deliver more power (and adjust the gearing to fit the new setup).

With the gearing optimised for bashing it will be a poor crawler.

[Whiplashdjs]

You can research batteries too, changing from a 2s lipo to a 3s makes a diff on speed and acceleration. But keep the limits of your esc and motor in mind also!