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Bearings mayhem

Discussion in 'Chassis & Drivetrain' started by JvG, Dec 21, 2017.

  1. JvG

    JvG Well-Known Member

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    Hi all,
    i need some help. I have a Kraton V2 and a Typhon V2 on 6S. Both are the best RC's i have owned. Fast, very tough and easy to maintain. The only thing that is really starting to anoy me are the rear hub inner bearings.
    After 2 to 3 packs i have to replace them otherwise they get stuck and destroy the hub. The front ones last for over 20 packs. I know the rear ones are more stressed but it's no fun anymore. I have found multipule threads in different forums about this problem.

    So i started to investigate what the problem is. I first made an outer protection but it made no difference:

    20171128_204235.jpg

    When i was cleaning the hubs yesterdey i noticed the inside of the hub and bearings is full of sand.
    So i started to investigate why and figured the problem is in the wheel axle. The slots in which the dogbone moves are too long and stretch beyond the bearing. Thats where all the sand comes in:

    20171221_173630.jpg
    20171221_173712.jpg
    20171221_173752.jpg
    The sand gets behind the bearing and is pushed in. The front CVD's do not have this design, they are closed, so i think that's (also) why the front ones last much langer.
    Now i am trying to find a solution. I have tried to close the slots with heatshrink tube:
    20171221_181327.jpg

    It doesn't really feel like a solid solution.
    I thought of placing CVD's in the back, but that's an expensive solution if possible. Maybe some kit or shoegoo but i doubt that's going to last. There is very little space between the bearing and the hub so the options are limited.
    Does anybody have an idea how to fix this for all Arrma enthousiast facing the bearing problems?

    Thanks!!
     
  2. Dustin Mustangs

    Dustin Mustangs Well-Known Member

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    Are you using sealed bearings? If not, those will likely take care of it.

    Another idea... is that exposed portion of the dog bone slot needed? If not, it would be pretty easy to fill it from the inside to plug up the gap. There are a ton of ways to skin that cat but I am thinking a 3D print would work great right there as long as it doesn’t get too hot.
     
  3. slick2500

    slick2500 Premium Member!
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    Dude this explains so much, my rear bearings would always be full of crud after a run but the fronts would be fine.

    @Dustin Mustangs if you look at the one picture you can see the blue seal on the bearing.
     
  4. Crash

    Crash Well-Known Member

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    Thanks for this post. I was unaware of this issue. Here are pictures of the fronts on the rear!
    20171221_185002.jpg 20171221_185113.jpg 20171221_185033.jpg 20171221_185345.jpg
     
    #4 Crash, Dec 21, 2017
    Last edited: Dec 21, 2017
    JvG likes this.
  5. jk420

    jk420 Well-Known Member

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  6. slick2500

    slick2500 Premium Member!
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    What the hell, I was always told that the front cvds didn't work.
     
  7. Crash

    Crash Well-Known Member

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    I ran the truck with the front drive shafts in the rear and it seems to run fine. The only issue I see is lifting the rear a arms creates a little binding near the differential cup. Depending on who you are that might not be okay.
     
    #7 Crash, Dec 22, 2017
    Last edited: Dec 22, 2017
  8. JvG

    JvG Well-Known Member

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    Do the CVD's in the rear hold up ok?

    I was looking for something like this (Tamiya):

    20171222_072226.jpg
     
  9. Crash

    Crash Well-Known Member

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    Yeah it's really close but in the end I definitely think a millimeter or two at the most on the axle shafts will probably be helpful. There's got to be some other brands that are Tad shorter that would work.
     
    #9 Crash, Dec 22, 2017
    Last edited: Dec 22, 2017
  10. slick2500

    slick2500 Premium Member!
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    Well color me intrigued. Guess who just so happens to have a spare set of axles.
     
    WoodiE likes this.
  11. Crash

    Crash Well-Known Member

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    Never worked on any other arrma vehicles. Is there one that might have a hair shorter cvds? Or shorter out drive cups from the diff. I do remember somone one here using the light weight losi out drive cups. If they were a bit shorter you would have plenty of room.
     
    #11 Crash, Dec 22, 2017
    Last edited: Dec 22, 2017
  12. JvG

    JvG Well-Known Member

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    I think the best option is to ask Arrma to fix it!
    I will sent my thoughts to them and let you know.....
     
    jk420 likes this.
  13. JvG

    JvG Well-Known Member

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    The Typhon front CVD's don't fit. I think the Kraton works because they are almost the same length as the dogbones.
    Back to the Typhon: the diff outdrives have sort of a stop. What if we use a dremel to remove them so the CVD's fit?
    20171222_215827.jpg
     
  14. Crash

    Crash Well-Known Member

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    They look like they don't stick out as far. Talking about the shaft that starts at the bottom of the cup and goes into the differential to the pin. Would be interesting to see that outdrive cup next to a kraton outdrive cup. Might just be the picture or the fact that I've been staring at my kraton for too long. But the shaft itself looks to be shorter. The only thing I own at this point from arrma is a kraton so I really wouldn't know.
     
  15. slick2500

    slick2500 Premium Member!
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    Just tossed the front cvds on the rear of my Outcast, fit like a glove, I have my grub screws turned down far enough to not have any sort of binding.
     
  16. Piecejointe

    Piecejointe Well-Known Member

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    And maybe Hot Racing so they can make something we can use soon?
     
  17. slick2500

    slick2500 Premium Member!
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    Idk how well aluminum stub axles would hold.
     
  18. Piecejointe

    Piecejointe Well-Known Member

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    They have nice steel cvd for some cars.
    Ok so maybe MIP.
     
  19. slick2500

    slick2500 Premium Member!
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    Have you actually read any reviews of their cvds and axles?
    I'll let the picture tell the story.
    Poop_Emoji_7b204f05-eec6-4496-91b1-351acc03d2c7_large.png
     
  20. Piecejointe

    Piecejointe Well-Known Member

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    Nobody seems to agree, are they bad?
    Re:Hot Racing I have a pair I'm pretty happy with on an ECX truck but it's their most expensive model (spring steel and stuff) and I've had the cheaper ones fail quickly.
    Does anyone make good cvds?
     
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