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Thread: Diff oil help

  1. #1
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    Diff oil help

    I race my Slash on a loose dirt oval and am having heat issues with my motor. On a 4 minute run I get my motor gets near 200 and that is in cool weather. I currently run 100 k in the front 200 k in the center and 10 k in the rear. My gearin is 11 pinion and 51 spur both steel gears and oversized bearing. The truck handles and pulls great the way it is setup but I need to fix my heat problem. Any suggestions with reasoning so I can learn would be greatly appreciated. I left out I use a 3s lipo.

    Thanks
    Last edited by Cowboy; 11-19-2012 at 04:58 PM.

  2. #2
    RC Turnbuckle Jr. spenniepoos's Avatar
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    Get a vxl esc fan and a fan for your motor and cut out some of the body to let cool air in to help with your temps..peace
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  3. #3
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    Quote Originally Posted by spenniepoos View Post
    Get a vxl esc fan and a fan for your motor and cut out some of the body to let cool air in to help with your temps..peace
    I have the front window open with a screen to keep dirt and rocks out and also run a fan on the esc. Do you think the motor fan would cure this?
    It was 45 outside during this weekends race and still hot.

  4. #4
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    Are you running the stock motor/esc? If so thats where your problem is. The Velineon runs fairly well on 2s but ALWAYS overheats on 3s. A cooling fan on the ESC and heatsink/fan combo on the motor helps somewhat but nothing alleviates the heat problems completely other than changing the motor/esc. Im running a Tekin RX8/T8 2650 combo with 23/50 gearing and mine stays very cool, no fan needed on the motor. It stays so cool in fact that I havent used a temp gun ever since I installed it and did tht initial set up. No matter how I geared it I never got above 135 on the motor after dogging it hard on 3s.

    You differential weights seem a bit high to what Im accustomed to running. I have mine set up F/C/R 10k/30K/5K but that has nothing to do with motor heating problems, just the way the truck handles.

  5. #5
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    Quote Originally Posted by JustinThyme View Post
    Are you running the stock motor/esc? If so thats where your problem is. The Velineon runs fairly well on 2s but ALWAYS overheats on 3s. A cooling fan on the ESC and heatsink/fan combo on the motor helps somewhat but nothing alleviates the heat problems completely other than changing the motor/esc. Im running a Tekin RX8/T8 2650 combo with 23/50 gearing and mine stays very cool, no fan needed on the motor. It stays so cool in fact that I havent used a temp gun ever since I installed it and did tht initial set up. No matter how I geared it I never got above 135 on the motor after dogging it hard on 3s.

    You differential weights seem a bit high to what Im accustomed to running. I have mine set up F/C/R 10k/30K/5K but that has nothing to do with motor heating problems, just the way the truck handles.
    I need to upgrade my motor esc combo definitely but don't have the cash right now, maybe I will try the fan on the motor. As far as the diff oil I have a lot of front pull out of the turns and I like that. Could I lower my diff oil F/C/R 25k/50k/2500 and have the same effect? I don't understand gear oil effects. Also do you think if I put a bigger pinion in it so I don't run wide open down the straightaways would that run cooler?

  6. #6
    RC Turnbuckle Jr. rag6's Avatar
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    It has not been mentioned, but once you get the motor over 200, you have done damage to the magnets. Repeatedly overheating it makes the problem worse, and the damaged motor will overheat even faster due to loss of efficiency. Putting a fan on an abused motor will not do much good. You may need a new motor, and surely a different (lower kv)wind to race a 4x4 on 3s.
    Wanna bash at Greenwood Bashplex in Pittsburgh ???

  7. #7
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    If you don't have the cash to change motor and or ESC, change your gearing. Hot Motor means you are undergeared, i.e. your ratio between spur teeth to pinion teeth is too big. Try with a bigger pinion. rag6 is right in saying you need to check your current motor as when temps exceed 200F it is not a good thing.
    Always get a 2nd Opinion!

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    Thanks all for the advise I don't think I have hit 200 on the motor but I will get a bigger pinion and a heat sink fan combo for the motor. I will post back with final set up if I can get it cooled down. Could anyone shed some light on diff oil and how it effects handling with thicker and thinner oils?

    Thanks again,

  9. #9
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    Put simplistically,

    In front, the heavier the diff oil, the more front traction you will have, but at the expense of steering.

    In the rear, the heavier the diff oil, the more rear traction you will have, but at the expense of steering, "rotation" in a turn, and stability over bumps.

    In the center, the heavier the diff oil, the more aggressive the car will feel.
    Always get a 2nd Opinion!

  10. #10
    RC Turnbuckle Jr. spenniepoos's Avatar
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    Yeah try a 13t pinion and see how it goes
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