What happens when I add one pinion tooth?
Adding a pinion tooth lowers final drive reduction, increases rollout, and can raise motor and ESC load. Check temperatures after the change.
Live tool / gearing plan
RC Gearing Change Planner
Compare your current setup against a controlled next pinion move. Keep the math visible, then test temperature and track response.
Pinion range
Adjacent pinion comparison
Select a realistic adjacent option to make it your specific comparison target. The recommended plan still advances by one tooth.
| Pinion | FDR | Rollout | Change | Action |
|---|---|---|---|---|
| 15T | 9.71:1 | 28.2 mm | -16.7% | |
| 16T | 9.10:1 | 30.0 mm | -11.1% | |
| 17T | 8.56:1 | 31.9 mm | -5.6% | |
| 18T · current | 8.09:1 | 33.8 mm | 0.0% | |
| 19T | 7.66:1 | 35.7 mm | +5.6% | |
| 20T | 7.28:1 | 37.5 mm | +11.1% | |
| 21T | 6.93:1 | 39.4 mm | +16.7% |
Keep calculating
Need the raw drivetrain math or a deeper speed estimate? Keep this change plan open, then verify the same inputs in the supporting tools.
Setup reference
What this calculator does
Compare your current pinion setup with a controlled next move to see the percentage change in final drive ratio, rollout, and estimated speed. Use it to keep gearing tests deliberate and repeatable.
FAQ
RC setup questions
Should I change pinion or spur gear first?
A one-tooth pinion change is usually the cleanest first test because it makes a smaller, easier-to-track adjustment.
How much gearing change is safe for an RC car?
Use small single-variable steps and monitor motor and ESC temperature. The safe range depends on the vehicle, surface, motor, and ambient temperature.