Yeti Rear Driveshaft Won't Spin

[robowarrior23]

Hey all,

I'm out of town and took my yeti to entertain myself, but it seems I've broken it pretty good. I only have limited tools with me to help determine the fault, so I'm hoping someone here can give me an idea what is wrong so I can go ahead and order parts.

My pinion and spur spin freely both by hand and using the controller, but the rear wheels do not spin. They appeal to be locked up. Disconnecting the drive shaft will allow the rear wheels to spin freely though. I've got a stripped screw and no tools to remove it that is preventing me from taking the transmission out to check its condition. The front wheels spin freely by hand, but won't spin under power from the motor.

Do you think I've stripped out my transmission gears? I'm running a HH 3500kv puller pro, mamba monster x, Robinson racing pinion and gen 3 slipper on 3s lipo. Could this combo really strip out the entire transmission?

I appreciate and help you insight you can offer.

[PileDriver]

So with everything put together its locked up and free revs?

[magic_yeti]

maybe your slipper or pinion got loose?

[robowarrior23]

Originally Posted by PileDriver

So with everything put together its locked up and free revs?

Yes, that is correct. Motor, pinion, spur all spin under power, but nothing is sent to the wheels.


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[robowarrior23]

Originally Posted by magic_yeti

maybe your slipper or pinion got loose?

I wouldn't think it's the slipper, since the rear wheels won't spin by hand either.


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[magic_yeti]

Maybe rear diff.
Rtr or Kit?
Do the trans Output f/r spin?
Just check the hole drive train what spins and what not easier with discon. motor. Hope u sort it out.

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[robowarrior23]

Originally Posted by magic_yeti

Maybe rear diff.
Rtr or Kit?
Do the trans Output f/r spin?
Just check the hole drive train what spins and what not easier with discon. motor. Hope u sort it out.

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Rear diff is fine. It spins freely when the driveshaft is disconnected. It would appear the trans output shafts aren't spinning, as neither front or rear drive shaft will spin under power.




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[robowarrior23]

Well for anyone interested, I was finally able get the stripped screw out and then get the tranny out.

Gear was sticking out of the case. Looks like a combination of the heat from the heats and the outside temp caused the plastic to expand enough for the gears to move around. Once apart the gears and bearings look good. Would seem that I just need a new case.




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[magic_yeti]

just a guess: I think a screw got lose and i see a lack of grease in it. which adds the heat component. if u need too get a new one may have a look at an alloy version for example
https://www.asiatees.com/display?-Ye...d=101108&pid=1

also i would consider an alloy motor mount if u still use the plastic one.

[DavidH]

Yikes. Thanks for posting the followup. I think that is the only part of my rtr yeti that I have not opened up.

[robowarrior23]

Originally Posted by magic_yeti

just a guess: I think a screw got lose and i see a lack of grease in it. which adds the heat component. if u need too get a new one may have a look at an alloy version for example
https://www.asiatees.com/display?-Ye...d=101108&pid=1

also i would consider an alloy motor mount if u still use the plastic one.

None of he screws were loose and most of the grease was clotted up with plastic shavings. Not to say I couldn't have been more liberal with the grease, but what's shown in the pictures of it being opened is after I'd removed a lot of the plastic and grease mess.

Found a new trans from a yeti rtr on eBay for 19 and picked up a boom racing aluminum case for 40. I'll use the gears from the rtr to put into the aluminum case, since buying new separate gears would've been more than the whole rtr tranny.

I was beating on it pretty hard in 100 degree weather, so it doesn't surprise that something broke. I just wasn't expecting what I found.


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[Cheez]

Let us know how the BR case works out. Considering it myself.

[poohsad]

My money was not on "gear melted through transfer case." Going to go grease mine.

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[CoolRunning]

For that to happen basically the bearing has to spin inside the transmission case which points to either a bearing failure so that a bearing became stuck on a shaft and heated up the case or a pin snapped and it did the same after things jammed up.

I drove my Yeti quite a lot in hot weather and the trans is one part that seems seriously tough.

Odd but unfortunate failure!

[mikemcE]

Have to agree, 100* is the norm here, i beat the tar out of mine on 3s with a Tekin 3000hd and tall super Swampers


Hang up and Drive

[shiftauto]

Have to agree with coolrunning. That looks like pin or bearing failure. The gears shouldn't even be able to move around in the housing if the bearings,pins,shafts are capturing the gears properly

[robowarrior23]

Well, I got the BR case and replacement gears installed and all is well again. I'm had some other boom racing products and been happy with them. The transmission case is no different. It's fit and finish is pretty good. Still pretty light in my opinion, but still nearly twice as heavy as the stock axial case.




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[shiftauto]

That'll get the driveshaft spinning again