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  1. #1
    RC Enthusiast
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    Best Spur Gear to Pinion Gear Combo

    Ok, I know it's a lot of personal preference but I'm hoping to get some feedback on what is the most popular combo gear set ups for street racing. I am running a 4 pole Castle 5700 with a 2s Lipo 5000 in my Rustler. I am mostly racing my car on my neighborhood streets. Right now I am running a 22/90 set up.

    Also can someone explain what using a larger spur gear versus a smaller gear does? Same thing with the pinion gear? Are there any charts anywhere explaining the performance difference using different gear combinations?

    Any suggestions on what combos to use under the following conditions.

    Fastest out of the hole take offs
    Fastest top speed performance
    Best all round performance combos
    Last edited by gdumond; 09-02-2012 at 08:31 PM.

  2. #2
    RC Champion
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    Using a bigger pinion has the same effect as using a smaller spur gear, only the results of changing the pinion will be magnified roughly 3 times. This is because the spur gear is usually roughly 3 times bigger than pinion, so one tooth change on the pinion is like a 3 tooth change on the spur. A bigger pinion or smaller spur will give you less acceleration, higher top speeds, and higher temperatures. A smaller pinion or bigger spur will give you more acceleration, lower top speeds, and cooler temperatures. I'd definitely get a non-contact thermometer to keep track of your ESC and motor temperatures. Traxxas recommends keeping everything under 200F but I stop running if I reach 150F to be on the safe side. Typical gearing is really any combination of pinions between 16t and 31t and spurs between 90t and 76t. It really depends on preference, ambient temperature, running surface and conditions, and an endless amount of other variables.
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  3. #3
    RC Turnbuckle Jr. O.G.'s Avatar
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    Try a 23/83 gearing and you'll run faster without much more heat in the motor. With this gearing you will have nice wheelies and a good top speed and should be around 50mph with stock tires on 3s.
    My Black & Blue Rally is faster than your color...

  4. #4
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    Thank you for the feedback and info. The nice thing about the new Castle 4 pole motors is they seem to run cooler. My old 2 pole was hitting around 185 degrees wheras my new 4 has only heated up to no more than 145 degrees. I'm using a hand held Duratrax Flashpoint gauge to measure the temps coming off the motor.

    I'll try out your suggestion on playing around with a larger spur and smaller pinion for faster acceleration.

    Quote Originally Posted by TraxxasTuesdays View Post
    Using a bigger pinion has the same effect as using a smaller spur gear, only the results of changing the pinion will be magnified roughly 3 times. This is because the spur gear is usually roughly 3 times bigger than pinion, so one tooth change on the pinion is like a 3 tooth change on the spur. A bigger pinion or smaller spur will give you less acceleration, higher top speeds, and higher temperatures. A smaller pinion or bigger spur will give you more acceleration, lower top speeds, and cooler temperatures. I'd definitely get a non-contact thermometer to keep track of your ESC and motor temperatures. Traxxas recommends keeping everything under 200F but I stop running if I reach 150F to be on the safe side. Typical gearing is really any combination of pinions between 16t and 31t and spurs between 90t and 76t. It really depends on preference, ambient temperature, running surface and conditions, and an endless amount of other variables.

  5. #5
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    Thanks O.G. I love the wheelies! I'll give that gearing a try!

    Quote Originally Posted by O.G. View Post
    Try a 23/83 gearing and you'll run faster without much more heat in the motor. With this gearing you will have nice wheelies and a good top speed and should be around 50mph with stock tires on 3s.

  6. #6
    RC poster
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    Sorry if this is a dumb Q but what do u mean "on 3's and on 2's"?
    Battery cells maybe??

  7. #7
    RC Racer
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    Yes thats battery cells. 2S fast 3S stupid fast! Thats how it was explained to me.

  8. #8
    RC Racer
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    Im running a 4 pole 3656 hobbywing sct 4000kv motor in my Bandit now with a 3 cell lipo - runs very well on the street with the 31 pinion and 76 spur!. Not much heat at all on the motor, just warm, cold esc and lipo.

    **** fast and wheelies at any speed - will flip on full acceleration even with the wheelie bar lol
    Last edited by Stach35; 11-19-2012 at 10:38 PM.

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