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Why is my 8.5 novak brushless motor getting hot

Why is my 8.5 novak brushless motor getting hot

Old 07-31-2009, 11:50 AM
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Default Why is my 8.5 novak brushless motor getting hot

i ahve a traxxas slash and i jsut got a 8.5 motor put on it and it seems like i rune it for like 10mins and its hot already idk wat setup to use with it and also i ahve the gtb esc from novak also
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Old 07-31-2009, 11:53 AM
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try different gearing
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Old 07-31-2009, 11:55 AM
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Originally Posted by roadrashracing View Post
try different gearing
like waht kind of gearing right now i have a 19/90 on it
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Old 07-31-2009, 11:57 AM
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I always try one or two teeth up or down, just watch the temps, check after a few min.
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Old 07-31-2009, 11:59 AM
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Probably too high of a gearing. I would drop down to a 17t pinion. Remember, the slash is a heavy truck.
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Old 07-31-2009, 12:00 PM
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Originally Posted by roadrashracing View Post
I always try one or two teeth up or down, just watch the temps, check after a few min.
i changed to 19/83
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Old 07-31-2009, 12:15 PM
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Originally Posted by Leroy1234p View Post
i changed to 19/83
That's just going to make it run even hotter. Try the aforementioned 17/90.
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Old 07-31-2009, 12:17 PM
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Its a big truck and if you have good rear tires on it that will effect it even more.
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Old 07-31-2009, 07:14 PM
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Originally Posted by Leroy1234p View Post
i changed to 19/83
you need to go down on the pinion to get a lower gear ratio...by changing the spur gear you actually raised the gearing instead of lowering it
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Old 07-31-2009, 08:25 PM
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Yes, the ratio between the pinion and spur gears is what makes the difference. If your motor is getting too hot, you're either driving it too hard or it's geared too tall.

If your gearing is too tall, the motor just plain can't "spin-up" easily enough and its trying REALLY hard to get up to speed. Using a smaller spur gear is the same type of change as using a larger pinion, either way you're making the ratio taller, and that makes the motor's job more difficult.

18/86 is stock. That's a pinion/spur reduction of 4.77:1. (divide 86 by 18 and you get 4.77, so the motor turns 4.77 revolutions for every one revolution of the spur).

19/90 is nearly the same ratio, 4.73:1. Since both gears are bigger by about 4%, you really didn't change much and the ratio is almost identical. Using a 20/95 (4.75:1) would also be nearly identical.

going to 17/90 gives you a 5.29:1 ratio. That's the direction you need to move, bigger reductions. Now the motor spins 5.29 times for each rev of the spur. Since the number is bigger, you have a "shorter" ratio, meaning the motor spins more easily and the truck moves a "shorter" distance for the same number of motor revolutions. This is like 1st gear in a car. As the motor's job becomes easier, it won't overheat as much. The difference in numbers is what makes the, uh, difference.

If you want, you can multiply any of these ratios by 2.72, (the transmission's own internal reduction) and you get the final drive to the tires. There's a chart that shows the final drive numbers in the manual, but its all based on the stock motor. The idea is still the same by changing pinion/spur sizes.
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Old 07-31-2009, 09:28 PM
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yea what wheelhaus said!!!!!!!!!!!! ha ha
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Old 07-31-2009, 10:06 PM
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I quit after the 2nd paragraphAnd have your sliper 1 1/4- 1 1/2 turn out from tight on your sliper for racing
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Old 08-01-2009, 09:56 PM
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For an 8.5 with a 90 spur, in a slash, you will need aproximately a 16t pinion depending on your track, or surface your using it on.

Brushless motors are geared differently than there brushed equivlants.
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Old 08-01-2009, 10:03 PM
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Originally Posted by wheelhaus View Post
Yes, the ratio between the pinion and spur gears is what makes the difference. If your motor is getting too hot, you're either driving it too hard or it's geared too tall.

If your gearing is too tall, the motor just plain can't "spin-up" easily enough and its trying REALLY hard to get up to speed. Using a smaller spur gear is the same type of change as using a larger pinion, either way you're making the ratio taller, and that makes the motor's job more difficult.

18/86 is stock. That's a pinion/spur reduction of 4.77:1. (divide 86 by 18 and you get 4.77, so the motor turns 4.77 revolutions for every one revolution of the spur).

19/90 is nearly the same ratio, 4.73:1. Since both gears are bigger by about 4%, you really didn't change much and the ratio is almost identical. Using a 20/95 (4.75:1) would also be nearly identical.

going to 17/90 gives you a 5.29:1 ratio. That's the direction you need to move, bigger reductions. Now the motor spins 5.29 times for each rev of the spur. Since the number is bigger, you have a "shorter" ratio, meaning the motor spins more easily and the truck moves a "shorter" distance for the same number of motor revolutions. This is like 1st gear in a car. As the motor's job becomes easier, it won't overheat as much. The difference in numbers is what makes the, uh, difference.

If you want, you can multiply any of these ratios by 2.72, (the transmission's own internal reduction) and you get the final drive to the tires. There's a chart that shows the final drive numbers in the manual, but its all based on the stock motor. The idea is still the same by changing pinion/spur sizes.
Good job.......
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Old 08-01-2009, 10:37 PM
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How hot is too hot? I've seen people say thier BL motors is too hot and I temp it at aoubt 125 deg. which is fine. If you put your fingers on a BL motor running at 160 deg. ( which is fine for any BL motor0 and it's gonna feel really hot. You really should give us a temp. so we better know what's going on.

And which 8.5 they aren't all the same.
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