ASK Cubby- Legit Questions, Bogus Answers

“Brushless Motors

Cubby,

Hi Cubby, I have been reading your columns forever, keep the good stuff coming.

My question for you is this, will a lower kv motor have more torque than a higher kv motor? I have a pair of Dynamite 540 brushless motors. The two motors have a different kv, yet both feel like they have the same torque. Everybody online says the lower kv should have more torque but that’s not what I feel when I drive them, they feel pretty much the same as far as torque goes.

Frank O.”

Cubby- Yo to the yo Frank, I hope you’ve been having an awesome week.

Ya know Frank, brushless motors are a much different beast than our old brushed units. I learned so much about them in the days when they were starting to take over from my homeskillet Shawn. I was from the brushed generation, he was 100% brushless from the air market, thankfully he was willing to share all the good inside info that would have taken me years to learn by myself.

So here’s the scoop Frank. I don’t have a good motor dyno at my disposal, like a proper, no BS one. So… I can’t simply grab a couple motors and find out for myself.

Yes, the science says that the lower kV unit should provide more torque, but I can not tell you first hand. Assuming you are comparing motors from the same company, that are the same size, but are simply different kV ratings, then yes, the lower kV unit should have more torque.

However, this is why you may not actually feel that while driving. All brushless motors today have an insane amount of torque. 4 poles have more than 2, but even a 2 pole unit has crazy torque from a dead stop, especially if you are geared tall. And it’s not like our cars/trucks are pulling heavy weights around (or climbing long hills), they are not. Therefore, if you pound the throttle on a high kV 2 pole, the amount of torque it has is wayyyy more than enough to rocket away from the starting line. You could then bolt in a 4 pole low kV unit, which only has more torque. Chances are, it will be hard for you to notice the difference between having way too more torque off the line, compared to even more wayyy too much with a 4 pole low kV unit.

And ya I know. On all the forums people will clamor on for days about why they spent more money on a 4 pole low kV over a 2 pole high kV just to get more torque, but if 2 pole is already more power than their tires and chassis can put down to terra firma, chances are they won’t notice a whole lot of real world difference.

“4-Tec 2.0 Or Other?

What’s up Cubby? I have never owned a touring car before, should I buy one with belt drive or one that is shaft driven?

Thanks,

Barry D.”

Cubby- Yo hey there Barry, thanks for taking the time to write in.

First off, I would like to say that it’s super cool that on-road is getting more publicity now days. As far as bashing goes (and racing too), on-road has been slowly dying off for years. Now, thanks to cars like the Traxxas 4-Tec 2.0, they are starting to gain some strength again. About time I say.

OK, so you want to know whether you should buy a touring car that uses a belt or one that uses a shaft. If you were to go around the room here, you would probably get plenty of answers for both sides, but here is how I see it.

I would go with shaft. Why? For reliability purposes. Yes, during heavy bashing you WILL end up bending the center driveshaft on a touring car, but the beauty of that is, it is easily bent back. You won’t have to spend much money, or time, to get it back to 100%.

I’ve found that belt driven cars handle a bit better and feel a bit smoother when on the gas. They also don’t have the torque steer that you find in shaft driven cars. But, I’ve also found that tiny rocks love to chew up the belts. I’ve simply had more issues with belt driven cars, that’s why I would stay away from them for hardcore bashing. Sure, if you are racing on a nicely groomed track and every tenth of a second is a big dealio, then yes, that is when you would want a belt driven car.

Just my opinion, which is worth exactly 0.000001 cents, but you asked for it. 🙂

There ya have it for today, another edition of ASK Cubby is in the books. Feel free to shoot me an email about anything or everything- thecubreportrc at gmail dot com.

YOUR Cub Reporter