You have to put something in there for tire diameter as this greatly affects the overall gear ratio. I think buggy tires are about 4" in diameter.

Here is what it says:

Spur/Pinion Reduction Ratio (?): 3.29 : 1
Total Reduction Ratio (?): 10.86813 : 1
Tire Circumference (?): 12.57 inches (319.19mm)
Total Motor Speed (?): 27750 RPM
Final Vehicle Speed (?): 30.38 MPH (48.81km/h)
Effective speed rate (?): 2.05mph/V (3.3kmh/V)

Since I would liek to go way above this speed; hoping to be about 45mph; how should I change the gearing to make it go faster, yet still keep the temps down?

I always use 4.5" for buggy tires. For the Lipo voltage, 3.5v/cell would be a more accurate figure.

Well, it did increase 2mph, so thats a start. Now if I changed the gearing to 41 and 19, do you think the system would run hot? Even with a fan and/or heatsink? It says it will be about 49mph, so that would just be awesome.

bump...bump. Anyone??? :012:

41? What spur gear is that?

The way I like to set up my vehicles' gears before trying anything out is by achieving a speed I know I can get out of them (based on a speed calculator like BrianG's). For XL motors on ~4s-5s, I like to shoot for 40mph. For my Revo, this way of theoretical thinking worked perfectly, as my motor has yet to exceed 150 deg. In some cases, the real speed might be higher than the theoretical speed. Like, for example, my X-Terminator. A highway patrol guy clocked it at 42mph, but based on the numbers I put into the calculator (46/13, Feigao 9L, 5 cells @2.8v, 4.5" tires) I should be getting 39mph.

Thanks. I guess that is what I will do. About the spur, I actually have no idea if one exists unless it is custom made. I just geared the spur down and pinion up to increase the speed a little.