[Chrislong]

Hi,
Ok the formula to use is: Spur / Pinion x 2.6

So for 81 spur with 21 pinion, that gives (81/21x2.6) = 10.02:1

This means 10.02 revolutions of the pinion = 1 revolution of the wheel&tyre.


Therefore: a torquey motor such as your stock, requires less turns of the pinion to drive the car forward by one turn of the wheel seeing as it has more power. So perhaps gear this on 81/24 or 25.

If you run a revvy motor which screams, chances are the torque is low, so you have to gear this with a smaller pinion as it will need to be made to rev faster to get the best from it.

Finally, im suprised you have managed to make the 84 tooth Losi sput fit, I am guessing you have had to dremel the chassis and the dogbone pins and the clearance is still tight at the outdrives. I run an 82 Losi spur so I can get low enough ratios with brushless, and for this I have had to dremel the chassis slightly too.

Chris