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need to gear down..

need to gear down..

Old 09-08-2010, 10:53 AM
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Default need to gear down..

i need to slow down. im currently running a 2200kv motor with a 43spur and a 15pinon. i easily overjumping the triples by 10+ feet
using the rc calculations website if i drop to a 12 or 13 pinion, ill take about 10mph off my top speed..
would that help make life a little easier on the track?
or would i be losing too much torque
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Old 09-08-2010, 12:04 PM
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Originally Posted by monkee
i need to slow down. im currently running a 2200kv motor with a 43spur and a 15pinon. i easily overjumping the triples by 10+ feet
using the rc calculations website if i drop to a 12 or 13 pinion, ill take about 10mph off my top speed..
would that help make life a little easier on the track?
or would i be losing too much torque
going to a smaller pinion would gain you torque. Your acceleration should be better also.
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Old 09-08-2010, 12:11 PM
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You don't need to really gear down, you just need to learn throttle control.

How to ease over the jumps and feather the throttle.
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Old 09-08-2010, 09:13 PM
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how would a smaller pinion gain me torque??

a smaller pinion and larger spur should give me less performance and longer runtimes yes?
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Old 09-08-2010, 10:08 PM
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Smaller pinion = more torque, less top speed, simple as that.
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Old 09-10-2010, 08:53 AM
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Originally Posted by Metalsoft
You don't need to really gear down, you just need to learn throttle control.

How to ease over the jumps and feather the throttle.
Originally Posted by racer1812
Smaller pinion = more torque, less top speed, simple as that.
Exactly on both.

I'm sure someone will jump in with all kinds of mathematical formulas as to why this is true but just know that it is. You can also gain more torque/less top end with a larger spur gear. The way it was explained to me is by thinking of a bicycle. The spur is the back wheel and the pinion is the pedals. Pretty easy to see from there.
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Old 09-16-2010, 11:15 AM
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Originally Posted by Neu_Racer
Exactly on both.

I'm sure someone will jump in with all kinds of mathematical formulas as to why this is true but just know that it is. You can also gain more torque/less top end with a larger spur gear. The way it was explained to me is by thinking of a bicycle. The spur is the back wheel and the pinion is the pedals. Pretty easy to see from there.
Here's a quick easy mathematical explanation:

The motor makes a set amount of torque. That torque gets mutliplied by the gear ratio (actually that and the internal ratio). The gear ratio number goes up as you go to smaller pinion. Therefore, the torque would go up.

Neu_Racer's bicycle analogy is spot on. You can only push so hard on the pedal. That force gets multipled through the sprockets to the wheel. Let's say you can push 100 lbs of force. If your gear ratio is 43 spur to 15 pinion as in OP's post, then that gives ratio of 2.87. 100 X 2.87 = 287 lbs.

Change the pinion to a smaller number, like 12. 43/12 = 3.58. 100 X 3.58 = 358 lbs.

The same is true with real cars. In 1st gear you get the most torque. 2nd gear is less and so on. That's because your gear ratio number is getting smaller because the pinion is getting larger.
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