Wheel Speed vs. Torque

By AR on Feb 01, 2013

Rock crawlers such as the Axial XR10 are “geared low” to provide the torque and power needed to climb over difficult obstacles. That’s pretty simple. For rock crawling, it may seem that the lower, the better. The more time you spend around rock crawling circles the more you may start to think differently as people talk about wheel speed and how rapidly spinning tires are sometimes the only way to conquer some obstacles. So which do you want, super slow torque or rock hopping wheel speed? How about if you have an Axial Racing Wraith which is known as a rock racer? Is the Wraith supposed to be slow of fast? How about a scale machine like the SCX10?

GEARING EXPLAINED
The quickest way to adjust the gearing on your Axial Racing vehicle and achieve readily noticeable results, is to change the pinion gear. If you were to change the stock 20-tooth pinion on your Honcho SCX10 RTR to a 25-tooth pinion, you would immediately notice the truck is faster. You will also notice less runtime and warmer electronics. And, you would additionally observe less climbing power. The opposite would happen if you changed to a smaller pinion. The spur gear, the counterpart to the pinion, works exactly the opposite of the pinion, so a larger spur gear than stock slows a vehicle down and a smaller spur gear speeds a vehicle up. It is important to note that a change in the same number teeth in the spur gear as compared to the pinion will yield a far less noticeable performance change. To see all of your gearing options, check out the Gear Ratio chart in the back of your Axial instruction manual.

MOTOR TURNS AND POWER
Axial’s ready-to-run SCX10 trucks, the Honcho and 2012 Jeep Wrangler Unlimited Rubicon, include 27-turn motors and the Wraith and AX10 Ridgecrest include 20-turn motors. Axial offers a 55-turn optional motor. A lower the turn rating equates to more speed but less torque. In contrast, the higher the turn, the more torque and less speed. Choose the motor that best fits the terrain and type of use you will most often encounter. For example, if you plan to enter your SCX10 scale competitions, swapping out the 27-turn for the 55-turn motor will provide low speed power and fine low speed control. If you want to have some high speed fun with your Wraith and don’t plan on technical rock crawling, a big change like swapping in Axial’s Vanguard 2900Kv brushless system may be in order.

VOLTAGE AND SPEED
When choosing gears and motors you essentially have a compromise on your hands. If you gear for speed with a large pinion, you give up low-end power. If you select a high-turn motor for torque such as a 55-turn, you won’t see a lot of speed. As they say, you can’t have your cake and eat it too. Or can you? The key to getting speed and power is voltage. If your speed control is rated to handle more than 7.4 volts, switching to a 3S LiPo pack (11.1 volts) will allow you to use a high turn brushed motor or low Kv brushless motor (both normally slower but higher in torque) and still have great wheel speed without needing a big pinion gear. The Axial AE-3 Vanguard can handle 3S LiPo and is also compatible with brushless and brushed motors. Always check your electronics specifications before making changes.

Because a higher voltage setup means smaller pinions can be used along with high turn or low Kv motors, the end result will actually be a system that isn’t working as hard as systems relying on large pinions and/or low turn or high Kv motors for wheel speed. This means the higher voltage setup can last mean longer lasting components.


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