Quick question about pinion gearing for young kids

[GodSpeed999]

I have my boys' Jeep geared (48P) with a 13T pinion combined with the 87T spur that came with their Recon G6 (AX90034).

Motor is a HH TorqueMaster Expert 35T. ESC is CC Sidewinder 3.

I intentionally chose the smallest pinion I could find to provide them with a nice slow crawling speed to learn with and to have lots of climbing power.

Now that they're quite comfortable with its control and a really quite good at slow obstacle crawling, it might be time to gear up a bit and allow them a bit more speed.

What I don't want is to lose low end power/torque. Does that happen with electric motors or no?

If I were to use the stock 20T pinion, is it going to be way faster and compromise low speed control, or is low speed control with these things more a matter of having high quality motor/ESC combos and good driver input?

Does that question make sense? Follow me?

Thanks.

[EeePee]

Originally Posted by GodSpeed999

What I don't want is to lose low end power/torque. Does that happen with electric motors or no?

...Follow me?

The motor is what makes the torque, not the gears. They have a specific output.

Ever ride a bicycle with gears? You're the motor, the gears are the same as a spur and pinion.

Follow you?

[wings_of_fire]

To elaborate on EeePee's reply,

The motor outputs power. Power in electric motors is composed of voltage and Ampere. In DC motors, voltage controls the speed of motor and load determines Ampere.
More volts = more rpm of dc motor.
More Ampere = when more torque is demanded by load.

So basically the motor tries to balance its input power to the fluctuating load requirement

[GodSpeed999]

Originally Posted by EeePee

The motor is what makes the torque, not the gears. They have a specific output.

Ever ride a bicycle with gears? You're the motor, the gears are the same as a spur and pinion.

Follow you?

Sorry if "follow me" was patronizing.

Anyway, yes I've ridden a bicycle and driven trucks and tractors. Gearing is important. You down shift when more torque/climbing power is required so I'm not sure this was the best example if I'm reading your information correctly.

What I think you're saying is that they will not lose climbing power (or slow speed control) if I increase the pinion gear; they'll just gain more top-end speed.

[meatmonkey]

That's not how gearing works. It's definitely a tradeoff of speed for torque, or vice versa. If you gear up and still try to crawl your going to put more load on the motor, which equals more amps, which equals more heat and reduced runtime.

If you have kids playing with it then leave the gearing alone. Slower is better for young drivers. You'll get longer runtimes, longer motor life, less broken parts, and the best possible crawlibility.

[Postclanker]

When I raced "go fast" on-road pavement/carpet racers....a smaller spur gear meant more torque out of the corner and less top end speed down the straight. If you wanted more top end, then you upped the spur gear (more teeth). This was with a brushless motor as well.

With a crawler, you need to consider weight more since it makes your motor work harder to move the mass....hence the meat monkey's comment...I am assuming that's with a brushed motor.

I would try a one or a two teeth increase at a time and watch your temp...a 13-20 tooth change is way too drastic at one time. You will eventually find your sweet spot

[nharkey85]

Originally Posted by Postclanker

When I raced "go fast" on-road pavement/carpet racers....a smaller spur gear meant more torque out of the corner and less top end speed down the straight. If you wanted more top end, then you upped the spur gear (more teeth). This was with a brushless motor as well.

This sounds backwards but i know you onroad guys ran ridiculous gearing to get the most out of motor limits

[Postclanker]

Originally Posted by nharkey85

This sounds backwards but i know you onroad guys ran ridiculous gearing to get the most out of motor limits

Yup, burned up my share pushing the limits...I'd much rather finess some rock

[bryantjt]

If you want to do both fast and slow, you have a few options.

1. 2 speed conversion kit from RC4WD but that requires at least a 3 channel radio to shift from 1st to 2nd.

2. Higher voltage batteries, if you are using 6 cell NIMH go to a 7 cell if your esc allows it. If you are using 2 cell Lipo go to 3 cell if your esc will allow. I believe the Sidewinder will work with either of the above options. Higher voltage spins the motor faster but you may need to adjust your gearing a bit if you run a 3 cell to keep temperatures under control since that is a big jump in voltage.

3. Gradually increase your pinion size to get the speed you are looking for. Yes, your low speed torque will suffer but that's just the way it is.

I have a G6 SCX-10 running an RC4WD 55 turn on a 2s lipo and have it geared 22/75 and it tops out at 4.35 mph according to RC Car Gearing (Android app). This is just over a walking pace at full throttle and has plenty of torque to drive straight up a wall.

If your 35T motor was similar in specs to an RC4WD 35T your trucks, with my 22/75 gearing would be running 6.89 mph which is pretty quick for a crawler. With this same thought in mind, your current setup should top out around 3.51 mph. Going to the 20 tooth pinion should put it up around 5.4 mph. Regardless of the MPH, going to the 20 tooth pinion would be about 1.5 times faster than your current gearing with a subsequent decrease in available torque. It's not that you won't be able to climb with it, just everything will get hotter than before because you will be working the motor harder, just like climbing a hill on your bike in top gear.

[GodSpeed999]

Thanks. Good post.

I think I have a 16T pinion gear too. I forgot. I think I'll try that one.