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Old 05-30-2007, 08:34 PM   #1
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Default Speed limit on GTB

I recently got a used GTB with a 5.5r but i'm pretty sure i'm not ready for the speed of the 5.5r yet.. apart from getting a slower motor is there a way to slow this beast down? will undergearing it damage the motor or cause overheating? what about if i just set the throttle down on my tx? Thanks in advance
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Old 05-30-2007, 08:36 PM   #2
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Quote:
Originally Posted by dorick
I recently got a used GTB with a 5.5r but i'm pretty sure i'm not ready for the speed of the 5.5r yet.. apart from getting a slower motor is there a way to slow this beast down? will undergearing it damage the motor or cause overheating? what about if i just set the throttle down on my tx? Thanks in advance
you can get the 8.5 (5800) its plenty fast a little faster than a 19t
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Old 05-30-2007, 08:37 PM   #3
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You could definately turn down the throttle EPA on your radio. Undergearing is never good.

-Marcos he doesn't want a new motor.
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Old 05-30-2007, 08:39 PM   #4
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do not turn down the thottle of your tx because it may heat up your esc and cause damage. do not undergear because going beyond the recommended gearing range may heat up your motor.

the best solution would be to get a milder motor
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Old 05-30-2007, 08:40 PM   #5
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Originally Posted by BlueBird-sr
You could definately turn down the throttle EPA on your radio. Undergearing is never good.

-Marcos he doesn't want a new motor.
oops didnt catch that, you can go down to 5 cells instead of 6 and it will be alot easier to drive and less wheel spin ,still will have a descent top end speeds
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Old 05-30-2007, 08:51 PM   #6
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throttle epa will heat up the esc huh... dang.. looks like i'm looking for a new motor :P thanks guys
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Old 05-30-2007, 09:03 PM   #7
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Quote:
Originally Posted by marvi
do not turn down the thottle of your tx because it may heat up your esc and cause damage. do not undergear because going beyond the recommended gearing range may heat up your motor.

the best solution would be to get a milder motor
why would that cause the esc to heat up?
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Old 05-30-2007, 09:18 PM   #8
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Quote:
Originally Posted by RussB
why would that cause the esc to heat up?
quoted from asw7576 - novak brushless thread ...

Quote:
Originally Posted by asw7576
Guys....

Don't set EPA ( full throttle ) below 100% as easy way...... The ESC heatsink will be hotter, why ? because ESC FET work as current limiter. At full throttle, the ESC doesn't limit the current, thus it will unleash full battery power to motor, On the otherhand, the ESC must limit full battery power ( lets say 80% full throttle ) and convert the excess 20% as heat.

You can try 5 cells ( 6V ) with 8 to 9 final gear ratio. Don't go higher or lower ratio ---> follow the gear ratio as in novak specification. However you can reduce the speed or power from battery power, ex. using 5 cells.

( I made mistake in the past, I bought 3.5R for 1/12 car..... it's crazy too fast, I cannot drive it at full throttle. So I keep driving it half throttle, and I notice the heatsink become too hot ...... even 1/12 cars are only using 4 cells. Now I'm using more reasonable power for 1/12 cars : 7.5R ).
Novak Brushless Thread
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Old 05-30-2007, 09:48 PM   #9
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I undergear my Novak Velociti motors (all with sintered rotors) and have no problems with motor heat.

I do run off-road, though, so for on-road, it might be different.

I gear to the point where I can fully squeeze the trigger on the straights but can still control my vehicle.

My gearing for my off-road vehicles:

84/20 on RC10B4 (2.6 int gear ratio) w/ 7.5R (might try 21 on my next race)
87/16 on RC10T4 (2.6 int gear ratio) w/ 6.5R
81/17 on DI (2.94 int gear ratio) w/ 5.5R (17T is smallest I can fit)

As far as I know, brushed motors overheat when they are undergeared or overgeared, while brushless motors only overheat when overgeared.
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Old 05-30-2007, 09:58 PM   #10
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ESC at 80% throttle will convert the rest 20% to heat???? The biggest BS I have ever seen.
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Old 05-30-2007, 10:00 PM   #11
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Quote:
Originally Posted by marvi
do not turn down the thottle of your tx because it may heat up your esc and cause damage. do not undergear because going beyond the recommended gearing range may heat up your motor.

the best solution would be to get a milder motor
I have turned down the EPA on the TX and it doesn't seem to make my ESC run hotter, in fact it runs cooler. I run a 5.5r turned down to 60% and it runs about 115F on both the motor and ESC.

That guy in the Novak Brushless thread said not to, but who is he anyway? It runs cooler if turned down!
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Old 05-30-2007, 10:17 PM   #12
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ok ...

here's what Charlie of Novak has to say

Quote:
Originally Posted by Charlie
...I think gearing the motor correctly, and driving it correctly are the biggest factor. Under gearing can cause heating problems as well. You end up "firing" a lot more often and the motor see's crazy RPM. By under gear I mean to small of a pinion, not the final number.

I've had some offroad drivers run a Motor that is "too fast" for the track, gear it normal, and then turn the EPA down. They report good temps and good feel. But this works because the loads in offroad are much different. Much less traction, so you don't "hammer" on it.

In On road when you have bit, the car setup and how it gets through the corner is super important. I've been to races for years, with regular motors, you can "tell" when the car is good, the motor stays in much better condition. With BL, you end up with no "signs" from the motor other then the temperature.

You're right, if the motor is going slower it's not working as hard. But you have to factor in the Load Now. Put load on the motor, and the RPM will change, as does the amount of current.

So if you're overgeared, and you apply full throttle or 7/8ths throttle, the load on the motor is still the same, its still trying to pull the same gear, just doing it with "less power" so it's making it worse. You see?
Quote:
Originally Posted by Charlie
Pheyhoe, Don't turn your EPA down to make it slower. That actually makes it hotter. If it's over geared, it's overgeared, doesn't matter how little throttle you use.

Gear down on the pinion for a smaller or tighter track.
i dont want to risk burning up $$$ because of undergearing/overgearing and turning down the EPA if there's too much power. i just do what the instructions tell me after all, its their product and they should know

well, i guess to each his own if undergearing or turning down the EPA works for you, then that's good
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Old 05-30-2007, 10:26 PM   #13
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Only turn down EPA combines with overgear will heat up the ESC, the heat comes from overgearing. When you gear it correctly and still think the motor is too fast, turn down EPA will not heat up the ESC more than normal.
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Old 05-30-2007, 10:38 PM   #14
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i run both a 4.5 and a 3.5 motor on my ta05-R and i really can't tell the difference in speed. the 4.5 runs much cooler than the 3.5 tho and i have the radio set at 160% throttle on the m11. i found out i was was breaking too much traction on the 3.5 that it heats the motor up fast and goes into a thremal shutdown on the gtb. i'm also running a max amp 7.4v 6000mah battery.
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Old 05-31-2007, 05:01 AM   #15
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hmmm! I've been running my Nosram brushless system with a 5.5t motor for around8 months now and when i race at my local club i turn my epa right down because the track is so small, and when i race on bigger tracks i turn it back up. Now i run the correct gearing for the motor and speedo and i have noticed that it comes off the track after 8mins (12th circuit) alot cooler then when i race at a big track!!!

my 2 pence
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