Choosing correct pinion and spur
- Thread starter Cumminz
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I don't do calculators but use my existing top speed to see where I'll end up. Say I have a 2050KV motor, and switch to a 1650KV.
To keep the same speed, say I have a 15t pinion, I'd have to go 15*(2050/1650) which is 20t when rounded up.
Of course, if it's a bigger or higher quality motor that you're upgrading to, you can gear up a couple of teeth for more speed.
Or google to see what the other guys are running
To keep the same speed, say I have a 15t pinion, I'd have to go 15*(2050/1650) which is 20t when rounded up.
Of course, if it's a bigger or higher quality motor that you're upgrading to, you can gear up a couple of teeth for more speed.
Or google to see what the other guys are running
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I use gear calculator apps to calculate approximate changes to speed using the stock setup as a baseline. Everything you need to calculate (internal gear ratio, tire sizes, etc) can be found on the arrma website and plugged into any number of calculators out there. The only thing that is sort of a guess is how much torque a motor will have vs. another and that is based on physical size of the motor as well as KV value so from there it's educated guessing and experimentation to find a good balance of torque and speed and avoid heat issues.
Here's some screenshots of calculations using a gear ratio calculator website (used to verify calculated internal gear ratio matched arrma's website) and an Android app I use called RC Car GearCalc. In the speed calculator screenshot I compare stock infraction with stock 4074 (2050kv) motor vs. stock infraction with the 4275 leopard motor (the 2200kv version).
The speed app doesn't care about motor rpm so note that both exceed 50k rpm with 6s meaning both of these setups are going a little beyond the typical max rpm (50k) for these motors so if you ran these this way the motors would be running quite hot if run flat out for long periods.
Links to apps/sites I used for reference.
RC Gear Calculator:
https://www.radiocontrolinfo.com/information/rc-calculators/rc-gear-calculator/
RC Car GearCalc App:
https://play.google.com/store/apps/details?id=redscrew.gearcalc
Infraction Spec Sheet for #s needed for calculations:
https://www.arrma-rc.com/vehicle-comparison/ARA109001
Here's some screenshots of calculations using a gear ratio calculator website (used to verify calculated internal gear ratio matched arrma's website) and an Android app I use called RC Car GearCalc. In the speed calculator screenshot I compare stock infraction with stock 4074 (2050kv) motor vs. stock infraction with the 4275 leopard motor (the 2200kv version).
The speed app doesn't care about motor rpm so note that both exceed 50k rpm with 6s meaning both of these setups are going a little beyond the typical max rpm (50k) for these motors so if you ran these this way the motors would be running quite hot if run flat out for long periods.
Links to apps/sites I used for reference.
RC Gear Calculator:
https://www.radiocontrolinfo.com/information/rc-calculators/rc-gear-calculator/
RC Car GearCalc App:
https://play.google.com/store/apps/details?id=redscrew.gearcalc
Infraction Spec Sheet for #s needed for calculations:
https://www.arrma-rc.com/vehicle-comparison/ARA109001
