Selecting the perfect gearing setup is a balancing act between torque and top speed. Our Kotouč Gearboxes Calculator shows the trade-offs clearly so you can tailor your build with confidence.
Mastering Our Gearbox Ratio Calculator : Step-by-Step
1) Start with Your Final Drive
Enter the Crown wheel and Pinion shaft tooth counts. The calculator computes the final-drive ratio (crown ÷ pinion).
If you have a single final drive gearbox enter in final drive number one, and the calculator will automatically read this information. If you have a 3 shaft gearbox with two separate final drives, then it does not matter which final drive number you use. Later, you will select the correct final drive, related to the specific gear.
Exploring hardware options? See our latest gearbox updates in STILL SHIFTING AHEAD: What’s New 2024–2026.
2) Define Your Tyre Size
Provide either the tyre circumference (cm) or the standard width / aspect / rim.
Want stronger, smoother parts? Learn why we build Isotropic Superfinishing into our gearboxes.
3) Set Your Maximum RPM
Enter your engine’s Max RPM. This defines the top-of-rev calculation point so the tool can estimate speed in each gear at your redline.
4) Add Tooth Counts for Each Gear
Depending on how many speeds your gearbox has, you can enter the correct number that fits your gearbox.
*for the 3 shaft gearbox it is important to select which final drive selects each gear.
Looking for no torque-interruption? Read our explainer on Seamless Shifting.
5) Read the Results & Graph
You can graphically see the results, if you want to change any parameters in the above table, the graph will change dynamically.
6) Experiment & Fine-Tune
Try taller or shorter final drives and adjust gear teeth until your speeds and RPM drops match the track. Pair your gearing with our Universal AWD Controller to tune torque split and response for surface and weather.
Ready to build the perfect gearbox?
Explore the calculator, lock your ratios, then talk to our team about a sequential solution tailored to your car.
Contact Kotouč GearboxesTip: Save multiple setups (different final drives or tyre sizes) and compare printed sheets in the pits to pick your gearing for the day.