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  1. #1
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    Should I change gear ratio from stock? 11.1vLiPo3s, 4x4 Ultimate

    I''m wondering if I should I change gear ratio from stock?

    I've had this 4x4 Ultimate for 2 weeks. It's my first fast RC car. I'm running 11.1V LiPo's 3s 20c only.
    I have a cooling fan on the controller.

    I normally don't run it very hard without some slower stuff mixed in. I've never really noticed crazy heat on the motor until I let a more advanced driver run my car for 10+ laps at an indoor track this week. He ran it very fast and hard.

    I was impressed to see what my car could do in more skilled hands, but the motor was very hot afterward and someone mentioned I should consider changing the gear ratio away from stock to save the motor.

    What is the stock gear ratio? 4x4 Ultimate
    Should I leave it? Change it?
    Advice?
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  2. #2
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    I would invest in a heatsink fan combo on the motor and i would only run 2s on the stock velinion. Way less trouble. But on 3s i would leave it stock gearing . On mine 2s i run 15/52 or 19 /54 depending on where im runnin. Im runnin two fans and heatsink on motor and fan on esc. Good luck
    EFFORT EQUALS RESULTS

  3. #3
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    Cool, Thanks,
    What kind of 2-fan heatsink do you have on the motor?
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  4. #4
    RC Turnbuckle Jr. El Sob's Avatar
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    I don't recommend a dual fan heatsink setup on 3s. The problem I had was, it overloads the bec in the esc. The truck will stop and freeze for no reason at all. Go with a single fan. You can also cut a hole in the windshield for more airflow to the motor. You can gear it down to a 11 or 12. That would also help.
    Slash Ultimate, ET-3S, 2400, MIP, King Headz, RPM

  5. #5
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    Quote Originally Posted by El Sob View Post
    I don't recommend a dual fan heatsink setup on 3s. The problem I had was, it overloads the bec in the esc. The truck will stop and freeze for no reason at all. Go with a single fan. You can also cut a hole in the windshield for more airflow to the motor. You can gear it down to a 11 or 12. That would also help.
    Thanks for the advice and help.
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  6. #6
    RC Turnbuckle Jr. El Sob's Avatar
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    You are welcome! We are here to help
    Slash Ultimate, ET-3S, 2400, MIP, King Headz, RPM

  7. #7
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    I guess it's time to put my ASE-Traxxas hat on...
    Gonna change the pinion / ratio tonight. I've heard it's an easy job...
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  8. #8
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    Quote Originally Posted by KewlToy View Post
    I''m wondering if I should I change gear ratio from stock?

    I've had this 4x4 Ultimate for 2 weeks. It's my first fast RC car. I'm running 11.1V LiPo's 3s 20c only.
    I have a cooling fan on the controller.

    I normally don't run it very hard without some slower stuff mixed in. I've never really noticed crazy heat on the motor until I let a more advanced driver run my car for 10+ laps at an indoor track this week. He ran it very fast and hard.

    I was impressed to see what my car could do in more skilled hands, but the motor was very hot afterward and someone mentioned I should consider changing the gear ratio away from stock to save the motor.

    What is the stock gear ratio? 4x4 Ultimate
    Should I leave it? Change it?
    Advice?
    i ran my 3s stock gearing at the track, my motor got 170 degress, god knows why it didnt burn out, i have 17/54 now and my motor doesnt overheat at all, you have to go to your lhs, pick up a 50,52/54 spur gear and several different size pinions and expiriment. get a heat gun by dynamite to moniter your temps.

  9. #9
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    Quote Originally Posted by El Sob View Post
    I don't recommend a dual fan heatsink setup on 3s. The problem I had was, it overloads the bec in the esc. The truck will stop and freeze for no reason at all. Go with a single fan. You can also cut a hole in the windshield for more airflow to the motor. You can gear it down to a 11 or 12. That would also help.
    would the pinion 11 and 12 run with a 54 spur gear? does the motor get hot? How fast will you go? on 3s right ?

  10. #10
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    Quote Originally Posted by traxxasFTW View Post
    would the pinion 11 and 12 run with a 54 spur gear? does the motor get hot? How fast will you go? on 3s right ?
    I haven't made the gear change yet. Perhaps today.
    I'll have to check on gear fit. My local shop told me the gear I need is in the kit that came with the car.
    The motor did get extremly hot during some very hard running (I loaned my car to a semi-pro / semi-abusive friend)
    It currently has way more top end than I need, so I can afford to lose some.
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  11. #11
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    Remember when looking for the right gearing and checking temps, if the motor is hot but the ESC isn't then it's undergeared. A lot of people don't realize that the motor will run hot when undergeared and they just keep going lower making it worse.
    I need R/Cers anonymous.

  12. #12
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    Quote Originally Posted by RobWilJas View Post
    Remember when looking for the right gearing and checking temps, if the motor is hot but the ESC isn't then it's undergeared. A lot of people don't realize that the motor will run hot when undergeared and they just keep going lower making it worse.
    Thanks, good info.
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  13. #13
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    I run 3s 20c no fans I have temp guage and I never get any problems no matter how hard I run it. Gear ratio 12/54. I use to run 19/54 learned the hard way. Fried the stock motor, the magnet was spinning on shaft rotor trXxas sent me new one week later. Props to traxxas.

  14. #14
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    My stock gearing is 13-54. The controller (ESC) does not really get hot, and I already have a cooling fan on it.

    My new car kit came with an 18 to replace the 13, but with a written warning to not use it on dirt tracks, and only on open road. So, I'll not change the 13>18

    Leaving the 13 in place, I could change the 54 to either the 52 or 50?
    I got a heatsink and single fan for the motor today. If that keeps the motor cool enough I'll leave it as is...

    I guess I'll look into the aformentioned dynamite motor temp checker...?
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  15. #15
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    The heat sink on the motor did the trick. I ran it hard today, and I was able to keep my hand on the motor afterward. It was too hot for that before.

    Thanks for the help
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