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  1. #1
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    I broke my Machined Spiral Cut Differential Gears

    I installed the spiral cut gears on the front and rear of my Xmaxx. On the second set of batteries with these Machined Spiral Cut gears, I managed to wheelie and to prevent from flipping over I tapped the brakes but I ended up hitting the brakes to hard and the truck slammed down and heard a LOUD click. Within 10 minutes 1 click turned in to 30 clicks and I pulled it apart.

    This is what I found:



    In case you guys are wondering, I am using a star pattern to tighten the diff. Cover screws and it's running completely stock everything except gearing... 15/54 gearing and using Traxxas 8400 Lipo's other than that the truck is completely stock.

    I'm not mad lol. But what now?!

  2. #2
    RC Qualifier NBViper's Avatar
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    I broke my Machined Spiral Cut Differential Gears

    All hope is with the Kershaws Design diffs now. Should be getting one of the prototype sets soon
    -=/ X-Maxx - 8S XLX/2028 \=-

  3. #3
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    Quote Originally Posted by NBViper View Post
    All hope is with the Kershaws Design diffs now. Should be getting one of the prototype sets soon
    Are the KDs spiral cut also??
    X-Maxx - 8S Castle XLX/2028

  4. #4
    RC Qualifier NBViper's Avatar
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    Quote Originally Posted by B1gDawg View Post
    Are the KDs spiral cut also??
    No clue, he's keeping the design under lock and key
    -=/ X-Maxx - 8S XLX/2028 \=-

  5. #5
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    Note to self. Do not brake.

  6. #6
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    Well this is interesting.
    Man i need more than 50 characters.

  7. #7
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    I have used the brakes hard on mine, flipping the truck over sometimes when I checked the differentials and greased them the front was in such good shape it was so sharp it pricked my finger

  8. #8
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    I beat the crap out of my truck last Saturday and my diffs are holding up well. I surely do hope this is not the norm for these gears :-(

    I'll just have to see how long mine last.

  9. #9
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    That's some crappy looking metal that they machined it out of.

  10. #10
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    My stock ones still look new

  11. #11
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    Wow that sucks I just ordered mine both front and rear this morning,doesn't Traxxas should replace that ?

  12. #12
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    Quote Originally Posted by Apexracing View Post
    Well this is interesting.
    Yea no joke!!!

    Here's some more pics:

    Some more information:
    When I pulled the stock ring gear and pinion out, I inspected the bulkhead for cracks, pits or anything out of the norm.

    I also thoroughly cleaned everything completely out and made sure there were no metal fragment from the stock gears and make sure it was 100% clean and ready to go before putting the machined gears in place.


    Last edited by Xmaxximum; 03-30-2016 at 09:19 PM.

  13. #13
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    Quote Originally Posted by Xmaxximum View Post
    Yea no joke!!!

    Here's some more pics:

    Some more information:
    When I pulled the stock ring gear and pinion out, I inspected the bulkhead for cracks, pits or anything out of the norm.

    I also thoroughly cleaned everything completely out and made sure there were no metal fragment from the stock gears and make sure it was 100% clean and ready to go before putting the machined gears in place.


    This made me feel that I just made a mistake spending $65 on a piece of metal;(

  14. #14
    RC Turnbuckle Jr.
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    Sorry this happened @Xmaxximum but thanks for sharing!

    Those gears cost a little too much to end of breaking off like that My stock gears have been holding up just fine so i'll stick with those.
    We are all one race. The human race.

  15. #15
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    Quote Originally Posted by PATS4LIFE View Post
    This made me feel that I just made a mistake spending $65 on a piece of metal;(
    How you think I feel!! I spent $95!! In fairness, mine haven't broken yet. Hopefully they won't break at all lol.

  16. #16
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    Please do us a favor of contacting traxxas and asking what to do next. I would like to know if they will warranty these parts or not. That tooth sheered off.
    Man i need more than 50 characters.

  17. #17
    RC Champion rizz0d's Avatar
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    i think your slipper is too tight. just coming down from a wheelie should not break that gear. i've landed some humungous jumps full throttle on the front wheels with no damage to the diff.
    Last edited by rizz0d; 03-30-2016 at 11:17 PM.

  18. #18
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    I would like to know what end of the car was the diff in? What surface was being run on, and how fast were you going when the brakes were applied?
    Man i need more than 50 characters.

  19. #19
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    Quote Originally Posted by Apexracing View Post
    I would like to know what end of the car was the diff in? What surface was being run on, and how fast were you going when the brakes were applied?
    On concrete on a residential Street.
    Probably around 15-25mph and it was the front diff.


    I guess I'm gonna loosen the slipper a little and try again.

    I'm calling Traxxas now.

  20. #20
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    Quote Originally Posted by Xmaxximum View Post
    On concrete on a residential Street.
    Probably around 15-25mph and it was the front diff.


    I guess I'm gonna loosen the slipper a little and try again.

    I'm calling Traxxas now.

    Just as I thought high grip surface and the front diff blows. The front diff is going to go every time braking hard on a high grip surface. Doesn't matter what the diff is made out of. I set all of my monster trucks with 30 percent brakes. Too much brake strength and stuff starts breaking.
    Man i need more than 50 characters.

  21. #21
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    Paint it black, and stamp a Heavy Duty sticker on it.
    Only 50 characters... :(

  22. #22
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    Quote Originally Posted by Apexracing View Post
    Just as I thought high grip surface and the front diff blows. The front diff is going to go every time braking hard on a high grip surface. Doesn't matter what the diff is made out of. I set all of my monster trucks with 30 percent brakes. Too much brake strength and stuff starts breaking.
    This is what I need to do. Thanks for the input.

    Just got off the phone with Traxxas and they were SUPER nice as always and wanted my diff gears shipped to them ASAP.

    They sent me a UPS shipping label and they are sending me new front diff gears today.

    Unbelievably helpful.
    I will also be loosening my slipper clutch quite a bit.

  23. #23
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    Quote Originally Posted by Xmaxximum View Post
    This is what I need to do. Thanks for the input.

    Just got off the phone with Traxxas and they were SUPER nice as always and wanted my diff gears shipped to them ASAP.

    They sent me a UPS shipping label and they are sending me new front diff gears today.

    Unbelievably helpful.
    I will also be loosening my slipper clutch quite a bit.

    Thats awesome news! Sweet!
    Man i need more than 50 characters.

  24. #24
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    Quote Originally Posted by Xmaxximum View Post
    This is what I need to do. Thanks for the input.

    Just got off the phone with Traxxas and they were SUPER nice as always and wanted my diff gears shipped to them ASAP.

    They sent me a UPS shipping label and they are sending me new front diff gears today.

    Unbelievably helpful.
    I will also be loosening my slipper clutch quite a bit.
    Are they sending u the same one or stock ones?

  25. #25
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    Quote Originally Posted by Xmaxximum View Post
    This is what I need to do. Thanks for the input.

    Just got off the phone with Traxxas and they were SUPER nice as always and wanted my diff gears shipped to them ASAP.

    They sent me a UPS shipping label and they are sending me new front diff gears today.

    Unbelievably helpful.
    I will also be loosening my slipper clutch quite a bit.

    I don't care if I get labeled a fanboy but that right there is why Traxxas is the RC RTR leader. Make sure you note for them the condition under which the diff (pinion) failed.

  26. #26
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    Quote Originally Posted by PATS4LIFE View Post
    Are they sending u the same one or stock ones?
    They are sending me the machined spiral gears of course

  27. #27
    RC Qualifier rtmike's Avatar
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    Are the wear marks normal. Looks like one bearing has more "wear".

    I thought I read the spiral stuff doesn't need to be shimmed. Any truth to that?



  28. #28
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    Yikes, that's not a good picture. I ordered my spiral gears and they should be here tomorrow. I specifically ordered these because my stock ring gear broke teeth. Good to hear Traxxas is taking care of you.

  29. #29
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    Looks an awful lot like powder metal.....
    Caution, this message contains words.

  30. #30
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    Quote Originally Posted by rtmike View Post
    Are the wear marks normal. Looks like one bearing has more "wear".

    I thought I read the spiral stuff doesn't need to be shimmed. Any truth to that?


    Does the stock ones need to be shimmed?and where does the shim go?i notice there's al little play on my stock gears

  31. #31
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    Yep. People keep throwing the machined word around. That just means it was cut from a solid block with a machine, but what was the block of metal made from? That should be solid and shinny where it broke off, it shouldn't have a cement type texture to it if it's high quality.

  32. #32
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    Quote Originally Posted by DreamState View Post
    Yep. People keep throwing the machined word around. That just means it was cut from a solid block with a machine, but what was the block of metal made from? That should be solid and shinny where it broke off, it shouldn't have a cement type texture to it if it's high quality.
    Yea almost looks like cast material. Apparently it seems like its a hardened coating, vs hardened steel.
    Man i need more than 50 characters.

  33. #33
    RC Qualifier rtmike's Avatar
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    Please correct me if I'm wrong. But shimming is required due to the tolerances from the manufacturing process being inconsistent.
    So in my mind it shouldn't matter whether it's spiral cut or stock, the tolerances won't be much different & should be firmed up regardless.
    I don't know, curious.

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