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  1. #1
    RC Racer
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    rear end smoking

    I was running my car the other day and noticed a loss in power so i pull over to check things out. I can smell burning plastic so i turn off the truck. I pick it up and the bottom on the rear skid plate it super hot. First i thought maybe i burned the slipper. I pull it out and check the clutch plate and everything looks fine. so i start to poke around and the bearing going into the rear dif was extremly hot. so now my question toall you experts is did i burn up my rear dif? I have yet to pull it apart but am curious if this problem has ever occurred to anyone else? TIA!
    Slash 4x4 MM2 2400kv

  2. #2
    RC Qualifier
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    Probably have some grit in the bearing, pull the diff apart and see if the bearing turns freely. If it's "lock'd" up, you'll have to replace it.
    rc10T3, TT Sparrowhawk XXB, Slash 4x4, 1/16 Rally

  3. #3
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    Do you have the aluminum bearing adaptor? I would get it if you dont. I have heard of lots of people having problems with it getting really hot and meltiing bearings without it.
    Slash 4x4 built from Proline RPM STRC TRX and MIP

  4. #4
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    thats the plastic piece that is between the spur and the slipper nut right?
    Slash 4x4 MM2 2400kv

  5. #5
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    Quote Originally Posted by pa4ul View Post
    thats the plastic piece that is between the spur and the slipper nut right?
    you may have melted that, or a bearing in the motor mount seized, spun and melted the plastic, or same thing in the rear diff...
    i'd find a bearing thats bad, and carefully inspect whatever plastic it rides in for signs of melt..

  6. #6
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    +1 ^^^

    Jackslash hit it on the head - I dont think its in the diff - I think its on the input shaft

  7. #7
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    Well i pulled apart the dif. The bearings all look to be in good shape. The only area i see any signs of melting or rubbing is where the clutch plate meets the bearing at dif housing. Can someone tell me how i can diagnose a bad clutch pad or bad playe. I can post pics tomorrow of it taken apart if you guys wanna take a peak.
    Slash 4x4 MM2 2400kv

  8. #8
    RC Turnbuckle Jr. El Sob's Avatar
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    You need to change your bearing adapter if it is plastic. To check the tightness of my clutch, I hold one end with a pair of pliers and turn the other with another pair. You can immediately tell how tight it is.
    Slash Ultimate, ET-3S, 2400, MIP, King Headz, RPM

  9. #9
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    you can see the weared area where the clutch plate meets the dif.



    Slash 4x4 MM2 2400kv

  10. #10
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    The slipper clutch got to far back and rubbed the housing. The only thing that holds in in place is the differential pinion gear. You need to replace the entire rear housing traxxas Part # 6680 and I would be looking at the bearing for that pinion as well to make sure its OK.

    My guess is the screws that hold the housing together were not tight. There are 4 coming in through the bottom skid and two that go through under the shock tower. If these are loose it will allow the differential pinion to slide back and make the whole rearend loose.

    If that wasnt it than you got a rock or something wedged in there.

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  11. #11
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    but everything else looks good right. that was the only part i could see that looked worn. Funny thing is when i pulled the truck apart those bottom screws appeared to be tight. Either way ill stop by the lhs and get the part stick it in and report back. Thanks for the help guys!
    Slash 4x4 MM2 2400kv

  12. #12
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    Just rebuilding my diffs too, does anybody know whats the heaviest weight oil I can use?

  13. #13
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    Quote Originally Posted by pa4ul View Post
    but everything else looks good right. that was the only part i could see that looked worn. Funny thing is when i pulled the truck apart those bottom screws appeared to be tight. Either way ill stop by the lhs and get the part stick it in and report back. Thanks for the help guys!
    Cant say if the diff is OK cant see in it LOL but it didnt cause your problem.

    Quote Originally Posted by TraxxasTMaxx2.5 View Post
    Just rebuilding my diffs too, does anybody know whats the heaviest weight oil I can use?
    Its all about how you want it to handle. the heavier the diff lube you use the closer it brings you to a locked diff. Too heavy will cause it to understeer in turns. Whats your primary use? If you have a stock ESC/motor with a slipper clutch 50K is a good starting point for bashing.

  14. #14
    RC Racer
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    well i replaced the dif case and all the bearings inside. I went out to run the truck and the exact same thing happened. not sure where to go from here.
    Slash 4x4 MM2 2400kv

  15. #15
    RC Turnbuckle Jr. El Sob's Avatar
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    You never included a picture of your motor mount. That could be the source of your problem. The plastic hub adapter is known for going out.
    Slash Ultimate, ET-3S, 2400, MIP, King Headz, RPM

  16. #16
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    i have a kingshead mount that is basically new. Could it have gone bad that quick?
    Slash 4x4 MM2 2400kv

  17. #17
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    Im trying to fathom how the slipper is getting that far back to rub the housing Even with a worn slipper shaft bearing but thats what its looking like, either that or something missing in the assembly. Did you remember the screw that goes in from under the slipper area on the chassis into the motor mount? When you pull your slipper out does if practically fall out or do you have to work at it. Should take some finagling to get it out. If it slops around its back to the slipper bearing. You can wear out a slipper shaft bearing really fast if you have the gear mesh set too tight. To set the Pinion/Spur gear mesh put a piece of paper between the two then push it snug, lock it down then remove the paper.

    If when you loosen the motor and swing it away from the spur and the slipper assembly wobbles around in the bearing either the bearing, the adaptor or both are shot. I just pulled the rear end out of my sons 4x4 with stock velineon and King Headz Motor mount and it wasnt even close and took me a few minutes to finagle the slipper out. Had to pull it back until the shaft popped off the front diff then pull the center shaft back forward before I could tilt it down to get it out. If none of these ring true can you post pics of both the slipper installed viewed from the rear end of the truck and the rear assembly in one piece? And also a pic of the slipper/motor mount from the top with it still installed.

    Looking over your photos I do note that you still have the plastic slipper shaft bearing adaptor but it doesnt appear to be worn, a bit hard to see.
    Last edited by JustinThyme; 02-07-2013 at 11:05 PM.

  18. #18
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    Justin Thank you for taking the time to help me! I actually solved the problem. I had read on a other thread about something expirencing the same smell. They ended up tightening the slipper nut and that solved the problem. So i tried it out and all is well again. now im popping wheelies nonstop. I might need to back out the nut a bit more.
    Slash 4x4 MM2 2400kv

  19. #19
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    That would explain a burning smell but not a melted housing. Either way is your slash even old enough to smoke?

  20. #20
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    lol! AT this rate i might need a breathalyzer before i begin to drive this rig the speeds im getting at!
    Slash 4x4 MM2 2400kv

  21. #21
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    Its scary sometimes! Ive only run mine at ludicrous speed a couple of times. Really fast is good enough. The first time you roll it at 70mph its enough to make a grown man cry! Been there and done that with a MMM/2200. I keep it down to the national rural road speed limit of 55 that is still stupid fast for an RC car.

  22. #22
    RC Racer
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    Talking

    oh man let me tell you. I think the fastest ive been up to is near 70 but i dont think i broken the threshold yet! YET! i run mine at the local mall parking lot which is huge and its next to a fairly busy road. I will sit there and wait for cars to get the green light and then race them to the end of the lot. I cannot count how many people have turned around and come to ask what in the heck i was driving! for me the speed hunt will never end though!
    Slash 4x4 MM2 2400kv

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