RC Car GearCalc
Proper gearing is one of the most essential tuning options required to maximize the performance potential of a touring car. The key to proper gearing is finding and maintaining the best rollout for each track environment, motor/chassis setup and driving style. Rollout is the distance a car will travel in one revolution of the motor shaft. Pinion and spur gears are used to generate the rollout desired, considering the diameter of the tires mounted. Rollout determines top speed and acceleration. Usually a higher rollout will provide less acceleration and more top speed, and a lower rollout will be quicker off the line, but with less top speed.
TRANSITION RATIO
The transition ratio is the ratio of all the internal gears from the transmission, including differentials and pulleys. The transition ratio is usually different for each model of car. Your owner’s manual should provide this information, but keep in mind that some manufacturers use the words transmission reduction to indicate the transition ratio. The transition ratio in most cases cannot be changed, unless you are able to change the number of teeth on the pulleys and/or gears.
PRIMARY DRIVE RATIO
The primary drive ratio is the ratio between the pinion and spur gear. This number is commonly rounded up to the nearest thousandth after the decimal point.
FINAL DRIVE RATIO
The final drive ratio is the ratio between the transition ratio and the primary drive ratio.This number is commonly rounded up to the nearest hundredth after the decimal point.
ROLLOUT
Rollout is the distance that the car moves forward for one revolution of the motor shaft (or pinion gear). Rollout is not affected by the motor, batteries, or electric components you are using; it simply defines how all of the gears, belts/shafts and tires work together to make the car accelerate and reach top speed. Rollout is calculated using the circumference of a tire and therefore the diameter of both foam and rubber tires make a difference. The diameter is more important if using foam tires since they can be used with a diameter anywhere from 64 mm down to 54 mm. As foam tires wear and get smaller, your rollout value will change a lot more quickly. Rubber tires do not wear down nearly as quickly or as much so the change to rollout will be very small over time.
Category : Tools
Reviews (16)
Good app but it's missing one major feature. It needs to be able to store multiple models! This is not usable for those of us with more than one rc car :(
Best one if your doing tire, pinion and battery swaps. This app allows you to switch metric to standard includes battery voltage, speed tire diameter. Only thing I would change would be maybe having both mph and kilometers maybe. It's pretty good as is I appreciate the work
I like it but I'd like some kind of tips or lesson with it, I did not know what some ratios where and how to work it out, for a beginner very annoying 😂 but it's good learning I'd like more from it and also maybe a nicer interface it's pretty dull and sad but it's such a exciting app calculating speed etc
For being free its a great tool even for just inputting hypothetical gearings and so forth to see what you can realistically achieve for speed running .. * this wont_cant include physics and real world effects as that would be impossible. Its already helped me get 84 out of an overweight Big Rock BLX on 4S if that says anything . Working on what i can get out of a tuphon on 6/8S . To the moon and good luck space cowboy....
Nice helpfull app. But would be better if we had the option to run mm tyre size and mph at same time. I work in mm and mph so have to keep flicking over in the setting.
Nice app, It would be good to be able to save settings for multiple cars and add motors.
Excellent app and excellent developer. After reporting a glitch the developer response was immediate, fixing the app in less than one hour. Priceless!!!
Otherwise good, but spur gear can't be lower than 50 *Edited, silly me, didn't notice setting. 5star and fast responce from Dev👍
works great for finding top speed and doing speed runs
Super useful for setting up cars
It was great i have a eztec rc car and i tuned it and it got faster
Works like it should. Great tool.
How do i add a decimal point? No option on keypad
Spur only goes down to 50? I have a 46 tooth spur what do I do now use 92 and double my pinion?
Add a compare option, meaning add new sliders for the pinion and spurs above the current ones(but smaller). Above all the results (if i use this pinion and this spur you get ???)
Could be improved by having slider options with settable limits and step amount for voltage (to make adjusting # of cells easier) and KV (to make common motor ratings divisible by 100 or 50 easier to set). Excellent app in any case. Edit: Thanks for adding sliders! I have another suggestion - Can you add a bookmark option for different car setups? I'd be happy to pay a few bucks if you added that feature to a paid version.