# John Deere 990 rear end explodes!



## Hoodoo Valley (Nov 14, 2006)

*OH DEERE* This looks like it's going to be expensive! What do you suppose would have caused this? The left side is fine as you can see, but the right was extensive. The whole planetary gear set, splined shaft, pinion and bearing are crushed. The plate directly beyond the pinion is destroyed as is the wheel bearing sets and seal. Began growling horribly immediately after my first hydraulic oil change about 350 hours and 8 years ago. While still under warranty, the dealer insisted it was just the wet disc brakes. Thanks local dealer! Now I drive 40 miles to another dealer where I actually bought the tractor. We're up to close to $3,000 in parts thus far.


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## Thomas (Nov 1, 2006)

OUCH:dazed: Bearing would be my first thought because of damage.


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## drmonsterbrain (Jun 7, 2013)

Looks like an inner final-drive/axle bearing failure to me. Two things could cause this on a new machine. Either the bearing was bad out of the box or (and most likely) the rolling drag torque was not set correctly during assembly.


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## Hoodoo Valley (Nov 14, 2006)

You've got my interest peaked here, because as I move toward fixing it, I'd like to avoid this again, and the manual says nothing about rolling drag torque setting, but then my John Deere manual reads like a modern Chiltons which are as vague as can be. My manual will say things like "Remove Differential. *GREAT!  How?*


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## wjjones (May 28, 2010)

tractor beam said:


> You've got my interest peaked here, because as I move toward fixing it, I'd like to avoid this again, and the manual says nothing about rolling drag torque setting, but then my John Deere manual reads like a modern Chiltons which are as vague as can be. My manual will say things like "Remove Differential. *GREAT!  How?*




What where you doing when it happened? Did you step on the rear diff lock, or ??. I hope you get it fixed Chris we have a few John Deere techs on here I bet they will know what you need to do.


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## drmonsterbrain (Jun 7, 2013)

If you stand the assembly on end with axle down, and rotate the axle housing with your hands while axle is fixed, it's the amount of force needed for the axle housing to begin to rotate. Essentially it's the same as setting bearing preload. There are shims in there. If this is set incorrectly, it will cause bearing failure! I will give you all info plus tips & tricks.


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## Hoodoo Valley (Nov 14, 2006)

So I located shims at the differential, but never saw any shims in the planetary pinion set. Where would these shims be, or perhaps this is why we had failure, because there weren't any shims?


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## drmonsterbrain (Jun 7, 2013)

There should be a shim set when you lift the planetary off the axle. I will look up info in a lil bit & get back at ya.


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## Hoodoo Valley (Nov 14, 2006)

drmonsterbrain said:


> There should be a shim set when you lift the planetary off the axle. I will look up info in a lil bit & get back at ya.


I would really appreciate that, thank you!


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## drmonsterbrain (Jun 7, 2013)

Best I can tell that lil tractor doesn't have shims like the larger ones. I attached some pics. Hope the info helps you.


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## Hoodoo Valley (Nov 14, 2006)

I have the same book. Okay, so I'm okay then. Still waiting on parts for assembly. My dealer is sure slow!


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