RC Car Gearing Ratio and RPM

RC Car Gearing Ratio and RPM
7 June 2022 20 view(s)

RC Car Gearing Ratio and RPM

Spur / Pinion Gear ratio calculation
If you want to get more speed from your RC car or truck you could
* Increase the pinion gear's tooth count or
* lower the spur gear's tooth count.
Both of the above options will decrease the low-end power of the truck while simultaneously increasing the overall top speed. 
If you want to gain more power, you could
* decrease the pinion gear's tooth count or
* increase the spur gear's tooth count. 
To determine your gear ratio, you divide the spur gear tooth count by the pinion gear tooth count:
 
STOCK 8S OUTCAST Baseline Gear ratio and RPM calculation
* Spur Gear divided by Pinion Gear = Gear Ratio
* 47T  divided by 23T = 2.04:3
* Spektrum Firma 1250KV x 29.6v divided by 2.04:3 = 18137rpm to Transmission

Alternative 8S OUTCAST Motor Castle 2028 - 800kv  
* Spur Gear divided by Pinion Gear = Gear Ratio
* 44T divided by 39T = 1.12:8 Gear Ratio
* Castle 2028 800kv x 29.6v / 1.12:8 = 21142rpm to Transmission
 
RPM INCREASE OVER STOCK SET UP IS = 3005rpm
 
IMPORTANT NOTE:
YOU MUST keep an eye on the heat of the motor if it gets too hot then a pinion or spur change may be required.
 
I hope this helps it might also be useful in selecting pinions and spurs for your other models if you ever decide to change
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