15T pinion, 61T spur
A 15T pinion on a 61T spur is a 4.067:1 spur ratio. With an assumed 2.85:1 internal ratio that is a 11.59:1 final drive, which on a 3200KV motor at 2S with 4.7 in tires works out to about 28.6 mph theoretical and 24.3 mph realistic.
5-Pack Steel Metal 32P 5mm Pinion Motor Gear Sets 13T 14T 15T
- 1/8
Pinion sets in 0.8 mod, the pitch this 61T spur uses. Buying a set lets you step one tooth at a time instead of guessing.
$12.99 listed price, changes often
Check price on AmazonWhat final drive does 15/61 give?
The spur ratio is 61 / 15 = 4.067. Your car's transmission or differentials multiply it. The internal ratio varies by model, so here is the final drive across the common range; find yours in the manual next to the gearing chart.
| Internal ratio | Final drive (FDR) | Character |
|---|---|---|
| 2:1 | 8.13:1 | typical 1/10 basher range |
| 2.5:1 | 10.17:1 | typical 1/10 basher range |
| 2.72:1 | 11.06:1 | typical 1/10 basher range |
| 3:1 | 12.20:1 | typical 1/10 basher range |
| 3.5:1 | 14.23:1 | short: torque, cooler |
How fast is 15/61?
Example: a 1/10 2WD truck, 3200KV motor, 4.7 in tires and an assumed 2.85:1 internal ratio (FDR 11.59:1). Theoretical speed is a no-load ceiling; the realistic figure assumes about 85 percent of it, which is typical on stock tires. For your own motor and tires, use the gear ratio and top speed calculator.
| Battery | Motor RPM | Theoretical | Realistic |
|---|---|---|---|
| 2S LiPo (7.4 V) | 23,680 | 28.6 mph | 24.3 mph |
| 3S LiPo (11.1 V) | 35,520 | 42.9 mph | 36.4 mph |
What does one tooth up or down do?
Speed scales with the pinion on a fixed spur. The heat rating compares each option with 15T, assuming 15T runs at a sensible temperature today.
| Swap | Speed change | Motor heat |
|---|---|---|
| 15T to 13T | -13.3% | cooler |
| 15T to 17T | +13.3% | high |
Which cars use a 61T 0.8 mod spur?
The 61T spur on this page is listed as fitting Arrma 1/10 2WD platforms such as the Fury, Mega Gorgon and Vorteks 4x2. Pitch matters more than tooth count: 0.8 mod gears only mesh with 0.8 mod gears. Set the mesh with a strip of paper between the gears as you tighten the motor, then remove it; there should be a tiny amount of play. See how to change a pinion gear.
15T on other spurs
Every pinion on the 61T spur
Gears and a thermometer for this swap
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Frequently asked questions
What is the gear ratio of 15/61?
61 divided by 15 is 4.067, so the spur ratio is 4.07:1. The final drive ratio multiplies that by your car's internal transmission or differential ratio, which is printed in the manual. At a 2.72:1 internal ratio it is 11.06:1; at 3:1 it is 12.20:1. Use the calculator with your own internal ratio for an exact figure.
Is 15T faster than 14T on a 61T spur?
Yes. On the same spur, speed scales with pinion teeth, so 15T is about 7.1 percent faster than 14T at the same motor RPM. The motor also works harder at every speed, so it runs warmer. Check the temperature after two or three minutes of running before going up another tooth.
Will a 15T 0.8 mod pinion fit my car?
Only if the spur is also 0.8 mod and the motor mount has enough adjustment for the pinion size. Pitch must match exactly; 0.8 mod gears will not mesh correctly with other pitches. Bore size must match the motor shaft, commonly 3.175 mm (1/8 in) on 1/10 motors and 5 mm on larger motors. The spur here is listed as fitting Arrma 1/10 2WD platforms such as the Fury, Mega Gorgon and Vorteks 4x2.
RCCarCalc is researched guidance, not professional advice. Figures come from published manufacturer specifications, listings and verified owner reports, not hands-on testing. Speeds are theoretical or as listed; real results depend on gearing, battery, tires and terrain. See how we research.