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  1. #1
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    Broken diff output shaft. Surprised that other parts didn't broke.

    So now I've had mu first broken part.
    I don't really remember doing anything stupid. While climbing some easy (but slippery) rocks the left rear diff output shaft just snapped.



    What broke is the part inside de diff. (Sorry for the bad picture). I was surprised that neither joint or the plastic axle broke. I expected them to break first and "protect" the diff parts.

    I already ordered replacement parts and I am preparing myself to removing an opening the diff, so my question is just for my understanding.

    Shouldn't other said parts break first? Could this be a deffective part?

    Thanks.

  2. #2
    RC Turnbuckle Jr. Wolfslash16's Avatar
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    Shouldn't other said parts break first? Could this be a defective part?
    Yes, and Traxxas did have a bad batch awhile back, I'd give them a call, they should cover it. I'd bet it's defective, judging by how the metal looks discolored. Good luck.
    2SummitE/TmaxxVillainSlash2&4SlayerPndeTeton

  3. #3
    RC Turnbuckle Jr. jamann's Avatar
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    There must be another bad batch or some of the original....original bad batch
    Diff lock side that's two in a week now,that I have seen.the bad ones were all diff lock output originally so it is the same issue? man,they must have a huge warehouse full of diff parts
    Fatski broke one yesterday when we were running.
    Email traxxas they will likely send you the parts.


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  4. #4
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    When did it break? Was that one axle caught on something? I've had sticks and weeds wrenched in the half shafts. Also, bad bearings will travel through the rest of your drive train.

  5. #5
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    It was not on the diff lock side. At least this is my understanding from looking at the exploded views.

    It sure didin't look as the wheel was caught up, but I can't rule that out.

    When I could't climb I backed up to go a different path and at first I thought that the rear diff didn't lock didn't engage as one wheel was spinning and the other was not. I disengaged the diff lock and picked up the truck and moved to smoother terrain to check the locking of the diff and saw that rear traction was compromised. That was when I saw the broken part.

    It really surprised me that the joint didn't suffer anything. I also found the color of the metal strange.

    It's not really about the 10 bucks of the replacement part. It's the "disassemble the rear part of the truck and open the diff and close everything back again" part that frustrates me.

    Also I live in Brazil so most probably Traxxas warrrant does not apply to my case. But I'll send an email to them. Can't hurt

  6. #6
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    I do not believe that it's a case of failing bearings as the truck is brand new. Probably doesn't have 3 hours total of running with it.

  7. #7
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    Haha. I broke the same one last night. But mine broke right at the gear and shaft so it wouldn't come out and couldnt see what was broke. Mine was my fault well my daughter fault. It was a summit dog pile and i was up side down and there was 3 other summits on mine and she hit the gas and peeled out on me and mine broke.
    _______^_
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    l_l O l_____l O l

  8. #8
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    Mine broke on the first run out of the box. Front left... took over 2 weeks to get the part. Really had me frustrated.

  9. #9
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    dont feel to bad. i broke the right rear out put on my first pack. iam going wirh bad batch. traxxas sent both sides right out
    My posts and summit are a hazard to your health

  10. #10
    RC Turnbuckle Jr. jamann's Avatar
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    You broke the "short" output?longer axle side
    That I haven't heard of.


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  11. #11
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    I broke the long on mine.
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  12. #12
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    yeah the short side on my first pack after the doing circles break in pack. first nite of a four nite camping trip. just my luck i guess. i need to leaen to post pics. how do you do it from a phone? would somebody be nice and pm this technology retard and help.
    My posts and summit are a hazard to your health

  13. #13
    RC Turnbuckle Jr. jamann's Avatar
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    I use tapa talk but photobucket has a mobile app as well.


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    Mountains cant stop me
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  14. #14
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    I've broken many half-shafts, but never an output shaft. All of the breakages happened because of my stupidity though
    This is a signature.

  15. #15
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    this pics for you jman and thanks for the heads up on tapatalk

    Sent from my PantechP9070 using Tapatalk 2
    My posts and summit are a hazard to your health

  16. #16
    RC Turnbuckle Jr. jamann's Avatar
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    no worries and that looks odd too me the pattern in the metal doesn't look right to me.
    no way that should break before a axle or the slipper slipping .I've twisted center shafts into pretzel's but never broke a short output ever. Bad locker side output broke one of those (bad one) way back.
    Mountains cant stop me
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  17. #17
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    yeah iam good at weard breaks . my old man says i could start the day with two steel ball bearings in my pocket and have them both broke by the end of the day.
    My posts and summit are a hazard to your health

  18. #18
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    Looks exactly like mine, from what I can see. As jamann said, it must be a bad part.

    I am waiting on the replacement parts to arrive to open the diff. I'll post some pictures as well.

    I'll also use the opportunity to do some small upgrades, such as changing rear shocks to double orange.

  19. #19
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    Broke my front output shaft on the front yesterday on the locking side. I'm like brunobaptista don't know when or how I broke it just noticed my front wheels were not turning.

  20. #20
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    So I received the parts and followed the guide in Traxxas' website on how to disassemble the rear end and take the diff out.

    I then opened the diff and replaced the broken output shaft. I decided to only replace it and the diff cup seal. I left everything else as it was. Reassenbled everything (put some grease in the pinion gear) and everything seemed ok.

    I didn't take any pictures of the process but here is the offeding part:



    Gave it some runs and everything was OK. As I grew more confident I tried harder courses in rocks when:



    And it happened EXACTLY on the rear left side where the old output shaft broke. Yes I am happy that it happened because this is the way it is supposed to break. I am OK with the concept of a cheap, easily replaceable "weak point" that protects other internal, more expensive stuff from breaking.

    And yes, it was user error (this time). Call it "learner's tax"

  21. #21
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    Quote Originally Posted by brunobaptista View Post
    Gave it some runs and everything was OK. As I grew more confident I tried harder courses in rocks when:

    WOW! I've never seen one look melted like this.

  22. #22
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    I believe the wheel was stuck pretty hard and I didn't notice until it was too late.

    I do have the metal center shafts installed. I believe that it may have helped to transfer the full wrath of the motor's torque to the half axles.

    I still have to get used with the amount of torque that the motor can deliver.

  23. #23
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    Those output shafts definitely look like bad casting. You can see where the break was before it actually let go.

  24. #24
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    Crock, can you point me to how can you say that based on the image?

    Not that I am doubting you, I want to learn .

    Thanks

  25. #25
    RC Turnbuckle Jr. jamann's Avatar
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    Quote Originally Posted by brunobaptista View Post
    Crock, can you point me to how can you say that based on the image?

    Not that I am doubting you, I want to learn .

    Thanks
    What leads me to that is the discolouration of the metal in a almost pattern.the shiny area in the middle hasn't been exposed to oxygen as long
    From what it looks like to me I'm no metal expert but that's what I see


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  26. #26
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    Quote Originally Posted by jamann View Post
    What leads me to that is the discolouration of the metal in a almost pattern.the shiny area in the middle hasn't been exposed to oxygen as long
    From what it looks like to me I'm no metal expert but that's what I see


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    i was thinking the same exact thing when i looked at it.

  27. #27
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    Yep that's what I was looking at. Could have been a hairline crack from casting that you would never see

  28. #28
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    Thanks guys.

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