studysession

A lot of people ask a lot of questions on gear ratios. I will edit this post from time to time making it more complete. For right now I am posting the internal gear ratios for most RC cars/trucks/buggy on the market. If you know an internal gear ratio that is not posted here, please send me a PM not an email letting me know. If I get an email and do not know who it is from, I delete them without reading.

Many thanks -

Q1. How do I figure out what gear ratio I am running?
A1. Take the # of teeth on you pinion gear and divide that # into the # of teeth of you spur gear. Then multiply that by your internal gear ratio of your transmission.
Example: I am running with a 72t spur gear and a 25t pinion gear in my TC3 and a TC3 has a 2.5 internal gear ratio. To figure out the final gear ratio, the math would look like this: 72 / 25 * 2.5 = 7.2 This means the TC3 with this setup is running a 7.2:1 gear ratio. Which means it takes the motor to turn 7.2 time for the tire to do 1 complete rotation.

Q2. How do I calculate my tranny gear ratio on a belt drive car?
A2. On a belt drive system, the gear that is in your differential is usually the bigger of the two and is called the spur gear. The pulley gears are usually where near where you mount your motor and those are your pinion gears. So take the pinion gear and divide it into your spur gear which gives the tranny ratio of your car.
Example: I have an electric Colt10 which is belt drive. The pulley/pinion gears have 15t and the diff/spur gears have 35t. The math would look like this - 35 / 15 = 2.33. So my tranny ratio for my car is 2.33:1. Now use this along with the math in question # 1 to get your final drive ratio.

Internal Gear Ratios:
Associated TC3 == 2.5
Barracuda R2/R3 ==2.4375
Ho Bao Hyper 10 elec == 2.13
HPI Micro RS4 == 1.0
HPI RS4 MT == 2.6
HPI RS4 Sport == 2 2.1
HPI Pro3 == 2.25
HPI Pro 4 == 2.4375
Kyosho mini-z == 1.0
Kyosho mini-z Monster == 5.0
RCLab (15/32) == 2.133
RCLab (15/37) == 2.466
RCLab (17/32) == 1.882
RCLab (17/37) == 2.176
Robitronic ETCV1 == 1.59
Schumacher 98/99/Axis == 2.00
Schumacher Mission/Mi2 (17T) ==2.12
Schumacher Mission/Mi2 (20t) == 1.8
Tamiya F1 == 1.0
Tamiya M01 == 2.4375
Tamiya M02L == 2.4375
Tamiya M02M == 2.4375
Tamiya M03 == 3.134
Tamiya M04L == 3.134
Tamiya M04M == 3.134
Tamiya TL01 == 4.447
Tamiya TRF414M == 2.133
Tamiya TXT-1 == 12.7575
Tamiya TT01 == 2.6
Tamiya TB02 == 2.6
Tamiya TB Evo III == 2.6
Tamiya Wild Dagger == 8.321
Traxxas Spirit == 2.94
Traxxas 4-TEC == 2.1
Traxxas Stampede == 2.72
Traxxas Rustler == 2.72
Traxxas Bandit == 2.72
Traxxas Sledgehammer == 3.75
Traxxas Nitro Sport == 2.81
Traxxas Nitro Rustler == 2.81
Traxxas Nitro Stampede == 3.75
Traxxas Nitro Buggy == 2.72
Traxxas Nitro Street == 2.72
Traxxas Monster Buggy == 2.71
X-Ray standard == 2.125
X-Ray low == 1.77
Teeam Losi XXXS == 1.83
Team Losi XX == 2.1905
Team Losi XXT-CR == 2.61
Yokomo MR4 TC-SD == 2.352
Yokomo YR4 == 2.333
Yokomo YR4 64DP == 2.333
Yokomo YR4 Jtype == 2.20
Yokomo YR4II MC == 2.20
Yokomo YR4II SP == 2.333

mkranitz

My Feedback: (60)

Great post. Please take a look at our Gearwizard calculator in the Community area and check out the Rollout value. I'm dividing the tire circumference by the final gear ratio to come up with that number. Is that correct? We've had some questions on it and I'd like your view.