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  1. #1
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    Exclamation Severe drivetrain bind

    I found some crazy drivetrain bind while servicing my bearings. I'm assuming this may be leading to a lot of diff and gear issues. Doesn't seem normal to me and this is my only rc that does it. Yes I checked them all. First remove gear cover. With truck sitting on table fully compress front end, let it come back up then the rear end. Do this as many time as you wish and you will see all your driveline gears lurch forward and reverse. The tires and cv shafts never turn. It's caused by something else and I'm not sure yet. As it appear to me, while jumping or bombing ruts, if the suspension doesn't move in tandom and one bottoms out first as it would bombing through a field or not jumping and landing on all four, the front and rear riffs are fighting eachother. I could be wrong as this is just an assumption. But my other trucks don't do this. My gears learch nearly a full revolution about the same as 6" of forward or backward movement. But the tires never move. It's just the diffs, center driveshafts, spur and pinion. If anyone needs a video I'll try and put one on YouTube. But, as I said, heres how I did my test. Randomly grabbed the front shocktower and just squished the truck to bottom out. Gears lurched. Do it again and nothing. Pushed the rear and same thing. Once you push the front down and gears lurch it'll do it again when you do rear. However. Front makes them move in REVERSE!!! and rear makes them lurch FORWARD!!! If you land nose first with wheelspin, the front and back will fight eachother. Same thing with bombing a rutted field going forward. If this is an actual issue and I'm not just understanding something, then traxxas definitely needs to get this fixed!! Let me know if you guys experience the same

    Check out this video on YouTube:

    http://youtu.be/G8qT21x15S4
    Last edited by Double G; 01-20-2016 at 08:02 AM. Reason: merge

  2. #2
    RC Racer dwilli9013's Avatar
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    well after trying mine Id have to say thats a very odd video. I do not get that kind of slipper movement.
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  3. #3
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    That's weird. Just checked mine and it does not do that.

  4. #4
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    Hmm... I did change to 16-50 gears. I wonder if that could have anything to do with it



    Tried to take a better video. Hard with one hand. The harder I push the more they lurch. Any ideas? I'm rather baffled. The chassis doesn't flex and it isn't broke. The only mods are simple gear change and integy fans. I just tore the slipper apart and cleaned it and tightend it down a bit more as it was slipping under heavy throttle. I have 50k in the diffs as I went heaver a couple nights ago when I serviced them. They both have a slight leak. Repacked them with hightemp marine grade bearing grease and also repacked diff bearings and both slipper shaft bearings with same grease as I found some seized. The bearings aren't very waterproof.
    Last edited by Double G; 01-20-2016 at 08:03 AM. Reason: merge

  5. #5
    RC Racer dwilli9013's Avatar
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    ahight just a guess here but with that gear combo when you flex the drivetrain hard not to get any kind of movement. From what Im reading you have very little give in your diffs. This would make this kind of slipper movement possible. Not a pro just my observations.
    XMAXX EREVO SAVAGE Digging Ditches

  6. #6
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    Here is my guess. First put the Maxx on a stand and feel how the wheels move by turning them by hand. I bet they are very tight with very little slop.

    I think with the diff's being packed with grease, you won't have much give in the gearing and drive train. As you move up and down in suspension movement, the drive shafts want to move and adjust during this movement. Then you tightened the slipper clutch even further. Step back a few steps and change the diff's lubricant back to what you had originally and loosen the slipper a bit and see if this changes things a bit. Sometimes too tight is not good in the differential with the marine grease.

  7. #7
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    Already gave that a shot. Refilled with 30 and barely applied the grease. Still doing it. I'm going to tare it down tomorrow and inspect all the driveline components. I've had a few on fb claim there getting some movement in there's as well. Two guys also did gear changes but one didn't. The guy that claimed to be stock said he had some bearing bind in both diffs and the problem went away after he replaced them. I'm going to recheck everything tomorrow. Even if both diffs were locked the driveline shouldn't turn just under suspension. I placed in on my stool so tires were off the ground and raised the arms and still had gear movement.

  8. #8
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    Hmm mine does do it and I have not changed a single thing except for adding a castle fan.

  9. #9
    RC Racer
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    Gotta be some kinda driveshaft bind. That's the only thing moving when the suspension moves. Are your drive cups that come out the sides of the diff severely worn? Like did the axle wear a round spot in the diff out drives? I believe that would do what what your seeing when when the axle moved in and out of the worn spot.

  10. #10
    RC Turnbuckle Jr. rag6's Avatar
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    Even though the tires are not turning, there is so much suspension travel that the large angle change when the suspension bottoms causes the bulkheads to rotate around the diffs. BOTH diffs. They are not fighting each other. Try the same thing with blocks under the suspension arms with all tires off the ground. You will see all the tires move very slightly and the center driveling will stay still. The tires will only move a little tho due to difference between the big ring gear and small opinion at the diff outputs, this is nothing to worry about. Does the same thing on my peed 4x4.
    Ya can't polish fertilizer...

  11. #11
    Marshal Double G's Avatar
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    Quote Originally Posted by rag6 View Post
    Even though the tires are not turning, there is so much suspension travel that the large angle change when the suspension bottoms causes the bulkheads to rotate around the diffs. BOTH diffs. They are not fighting each other. Try the same thing with blocks under the suspension arms with all tires off the ground. You will see all the tires move very slightly and the center driveling will stay still. The tires will only move a little tho due to difference between the big ring gear and small opinion at the diff outputs, this is nothing to worry about. Does the same thing on my peed 4x4.
    I agree with this. Note the spur spins different directions depending on which side you push down. If there is any binding in the system you will know it by higher motor temps and drag either by premature stopping or turning to one side. If you want to make sure, isolate parts of the drive train to determine where the binding may be.

    This "issue" happens in my nitro Revo and is nothing to worry about.
    The Super Derecho

  12. #12
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    Seems most think it may be ok. Eitherway, I'm tearing the entire driveline down tonight. I'm going to clean and grease everything and check for any binding. If it still does it, I'm still bashing. Lol I only worry cause it's the only truck to do it. Doesn't seem normal but hey, I'm just a hobbiest not an engineer

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