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Old 11-17-2008, 09:11 AM   #1
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Default Outdoor gearing and temperature...

After my last meeting at a track outside, I began thinking if the weather temperature has that much to do with gearing.

If my motor has cold air rushing around it in the winter months, compared to much warmer air in the summer months, surely this could well change how I gear it?

If you are smooth on the throttle and you have cold air around the motor, surely the motor wouldnt go off so quickly than in summer. Or is it not that significant to worry about?
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Old 11-17-2008, 09:26 AM   #2
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Hi Chris,

With brushed stock motors (as you're running) being cold does not give more power to the motor so you should be gearing it to rev out towards the end of the straight. The outside temperature only really comes into play when it is hot and you have to gear more conservatively to make 5 minutes.

With brushless motors, it is slightly different in that you normally gear to the temperature at the end of 5 minute run - meaning you keep on adding teeth until it is gets to the target temperature. Then the cold air would aid in keeping the motor cool and allowing you to gear up (within the power limit of the motor of course).

Hope that helps,

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Old 11-17-2008, 09:31 AM   #3
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It definitely makes a difference. But it also depends on a few other factors.

When it is colder, your batteries may have less punch depending on how much colder it is.

Tire Grip drastically changes. This can make it feel like you have more power due to wheel slippage.

Also, it depends on the class and how if any of the air can get to the motor. When I used to run brushed it could make as much as 3 pinion teeth difference on the motor from 70 to 90 degree days in off-road.

In on-road, I can't really tell you a difference, as my 1/12th scale doesn't really get hot either way since I can't gear it up all the way. (Otherwise I wouldn't make run time on the open layout we have.)

In touring car, yeah it's made a difference. Most notably that temp difference is big on my lipo battery. When above 90, I have to keep a close eye on my lipo as I had one swell up on me due to high track temps.
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Old 11-17-2008, 09:49 AM   #4
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Thanks for the inputs, having raced indoors for quite a few months its not something i've had to consider factoring into the racing recently

Adding to which, when I did go racing about a week ago outdoors, my motor was barely warm after 5 minutes although the gearing/punch/speed seemed to be good for the motor I was using according to the regulars, hence got me thinking about it.

Dont get me wrong, I love speed as much as the next guy standing next to me on the rostrum, but surely if I gear the car to rev out at the end of the back straight, it will struggle to accelerate that well on the tighter infield, the length of the back straight is not likely to be as long as the total length of the infield, where time is made up from a car that will accelerate well out of the corners, well to a certain degree.

Maybe my thinking is flawed though....
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Old 11-17-2008, 11:53 AM   #5
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correct me if i am wrong, but the batteries would perform worse in the cold.
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Old 11-17-2008, 01:00 PM   #6
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With no discredit to who have already replied, are there any motor tuners out there reading this who have visited the same track with the same motor, but on a hot and cold days racing and noticed the need to change gearing between the two?
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