Why is my 8.5 novak brushless motor getting hot
07-31-2009, 11:50 AM
#1
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
07-31-2009, 11:53 AM
#2
try different gearing
07-31-2009, 11:55 AM
#3
Originally Posted by roadrashracing
try different gearing
07-31-2009, 11:57 AM
#4
I always try one or two teeth up or down, just watch the temps, check after a few min.
07-31-2009, 12:00 PM
#6
Originally Posted by roadrashracing
I always try one or two teeth up or down, just watch the temps, check after a few min.
07-31-2009, 12:17 PM
#8
Its a big truck and if you have good rear tires on it that will effect it even more.
07-31-2009, 08:25 PM
#10
Tech Initiate
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.
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.
07-31-2009, 09:28 PM
#11
yea what wheelhaus said!!!!!!!!!!!! ha ha
08-01-2009, 09:56 PM
#13
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.
Brushless motors are geared differently than there brushed equivlants.
08-01-2009, 10:03 PM
#14
Originally Posted by wheelhaus
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.
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.
08-01-2009, 10:37 PM
#15
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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.
And which 8.5 they aren't all the same.
