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  1. #1
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    I think I found the next weak link

    So I got the Front axle fixed last night made it through another two tanks this morning now I seem to Have broken the trans. This seems to just become a 2 Wheel Dr. Rear wheels only! Front driveshaft still looks good just the front wheels Are not turning! Should I fix this trans or is there better one I can put in it?
    Desmosedici RR

  2. #2
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    What engine do you have in the truck? What trans and is it FOC'd? If it's not FOC'd you may have stripped a gear and caused it to only be RWD. You can disconnect the driveshaft from the trans and spin the driveshaft, and if the wheels move freely, then you know that the problem's on the trans and not the diff.

  3. #3
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    It's a fresh 3.3, stock black trans with no FOC. Now that its cooled off every thing seems to be in working order. If I turn the front axles in the same direction the rears will turn too and it doesn't feel notchy or any thing. If I turn the brake disc all axles turn. Turning the front axles in different directions I don't feel any binding or notchy feeling like the diff is damaged I drove it around for a while in 2WD. A little squirrely but fun before packing it up and heading home I held it in the air and did a few light revs and there was nothing to the front wheels.
    Desmosedici RR

  4. #4
    RC Turnbuckle Jr. Wildman4910's Avatar
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    I would look at the front center yoke pins, then front diff first.

    The output shaft in the trany is one piece.

    Below is a FOC output shaft.
    Look out for the tree/crunch!

    LiPo? Naw NITRO!!

  5. #5
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    When you say ctr yoke pins are you talking about an internal part or where the ft drive shaft goes onto the trans and the ft diff?
    Desmosedici RR

  6. #6
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    Don't know if this will help or not. If I lock the front pinion in place, I. Can still turn the front axles in the same direction with very little drag.
    Desmosedici RR

  7. #7
    RC Turnbuckle Jr. Wildman4910's Avatar
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    Do you mean if you hold the front diff pinion you can spin both front tires in the same direction?

    The tires should rotate in opposite directions with the pinion held still.

    The pins that hold the driveshaft yokes to the output shaft & diff pinion.
    Last edited by Wildman4910; 01-19-2013 at 05:00 PM.
    Look out for the tree/crunch!

    LiPo? Naw NITRO!!

  8. #8
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    If I hold the pinion and only spin one axle the the other will turn the opposite direction. If I wedge the pinion and use both hands I can spin them both in the same direction. PinS appear to be good.
    Desmosedici RR

  9. #9
    RC Turnbuckle Jr. Wildman4910's Avatar
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    You should not be able to spin them in the same direction with the pinion wedged/jammed.

    Time to pull the front diff & see what detonated, I think your gonna find a damaged Ring & Pinion.
    Look out for the tree/crunch!

    LiPo? Naw NITRO!!

  10. #10
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    It could be one of the pins or you could have stripped a hex so that the diff unloads to that tire giving the impression that something else broke.. Spin the front center shaft and try to hold one or both of the tires and see what happens.
    The Super Derecho

  11. #11
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    If it's a front diff for a ring and pinon I'm stylin! Got a spare diff sitting right on the bench waiting for a home! I can't complain much, it's original and it's been through about 9 gallons of fuel!
    Desmosedici RR

  12. #12
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    Well boys and girls I don't see any catastrophic failure of the diff? Aside from a questionable side bearing every thing looks stellar. Any more advice would be appreciated.


    And +1,000,000,000 to Traxxas for coming up with the worlds only non dilutable/cleanable/cutable/thinable diff lube!!!!! What in the world do you clean this stuff up with????????
    Last edited by Redvegasgt; 01-19-2013 at 10:01 PM.
    Desmosedici RR

  13. #13
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    Well, I guess now it's time to open up that trans and see what's messed up in there if nothings wrong with the diff. You might want to drive it again and make sure that there still isn't any power going to the front wheels.

  14. #14
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    I'd swap out the diff any way as long as your there and have it all apart.

  15. #15
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    I pulled the new diff apart to compare and there was a catastrophic failure. Just not to my untrained eye. The ring gear that would be attached the the carrier assy in a real diff were separated in this one. Looks like the four screews the go through the back side of the ring gear got ripped out of the plastic drum that contains the spider gears. Putting the new diff in right now.
    Desmosedici RR

  16. #16
    RC Turnbuckle Jr. Wildman4910's Avatar
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    PIC'S!.......Must......Have.....Carnage......PIC'S !

    Good to hear you found it.
    Look out for the tree/crunch!

    LiPo? Naw NITRO!!

  17. #17
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    LOL there's really not that much to see but I'll post em as soon as I get the parts cleaned up. The only clue was that the one piece thingy in the good diff was a two piece thingy in the bad one. All the spiders and the ring and pinion look to be in really good shape. When the rear one blew up THAT was carnage! KABLOOEY
    Desmosedici RR

  18. #18
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    Good thing you caught it. Nothing worse than thinking you're golden then it turns out you'll have to rip the dang thing apart again just to fix what could've been done the first time!

  19. #19
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    Not much to see but here the carnage Wildman.

    http://pic20.picturetrail.com:80/VOL.../405353395.jpg

    http://pic20.picturetrail.com:80/VOL.../405353394.jpg

    Any one know if I can get just that piece? I can put this thing back together and have another spare sitting on the shelf again.
    Desmosedici RR

  20. #20
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    if its the older style 2.5-3.3 grease filled diff you cant just buy the cup
    you need part 4981 which comes with the cup ring and pinion

  21. #21
    RC Turnbuckle Jr. Snook Man's Avatar
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    Quote Originally Posted by Redvegasgt View Post
    And +1,000,000,000 to Traxxas for coming up with the worlds only non dilutable/cleanable/cutable/thinable diff lube!!!!! What in the world do you clean this stuff up with????????
    Carb cleaner cuts diff oil/lube like warm butter and a sharp knife.
    No slipper/tall gearing/power = broken parts.

  22. #22
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    Carb cleaner also makes the entire block smell like carb cleaner for a week. Wife would not appreciate this!
    Desmosedici RR

  23. #23
    RC Turnbuckle Jr. Wildman4910's Avatar
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    Brake Clean works well too, just use gloves & safety glasses as it is some mean VOC that you don't want soaking into your skin or getting into you eyes/on your face when spraying.
    Look out for the tree/crunch!

    LiPo? Naw NITRO!!

  24. #24
    RC Turnbuckle Jr. Nitronaught's Avatar
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    Quote Originally Posted by Redvegasgt View Post
    If it's a front diff for a ring and pinon I'm stylin! Got a spare diff sitting right on the bench waiting for a home! I can't complain much, it's original and it's been through about 9 gallons of fuel!
    So do you think that maybe there had been a problem in your front diff that could have possibly caused a chain reaction and caused your driveshaft issue?
    Founder of H.U.A.
    Hop Ups Anonymous

  25. #25
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    If any thing I'd say it was vice versa. Drive shaft might have caused the diff. I remembered afterward (with the dshaft) that straight out of the packaging one of the joints was pretty stiff. All the others were nice and loose. But one was really right. I figured, well it's not seized, just put it in and it will loosen up while running. Oh it loosened up alright! Any way. Those are steel driveshafts. I highly doubt the plastic diff took one of those out.
    Desmosedici RR

  26. #26
    RC Turnbuckle Jr. Nitronaught's Avatar
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    Quote Originally Posted by Redvegasgt View Post
    . I highly doubt the plastic diff took one of those out.
    I'll give you a great example of a plastic diff cup witha plastic diff case that CAN do that...

    Screw backs out of the ring gear slowly, just enough for it to catch on the internals and lock solid,,,, SNAP goes your steev cvd ot the output shaft of the tranny... OF course that happens when you are in 2nd gear going full tilt boogie and you watch your RC tumble down the road as the front wheels had locked up...

    Just because the diff case and diff cup maybe plastic, the ring gear, the bearings,,, those are hardened steel... SO do not be fooled, it can and does happen...
    Founder of H.U.A.
    Hop Ups Anonymous

  27. #27
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    Didn't think about it that way. That prob would have provided some more exciting carnage shots!
    Desmosedici RR

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