Rear t-case output shaft loose

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arielflash

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Hi all...
I have vibrations starting at 60~ mph...
While inspecting rear driveshaft, axle angle, etc - I have noticed that when I grab the front of the rear driveshaft (where the harmonic balancer is) and try to move it up and down - there is a play... feels like the loose part is the shaft/transfer contact (and not the ujoints on the driveshaft which has been replaced recently)

Is it supposed to be a bit loose or no movement at all ?
 

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mrlavalamp

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I checked mine and I have a small amount of movement here as well, but very small. Hard to tell if it is the spline or the output shaft, but it is not sloppy movement and parallel to the axis of the shaft. I don't have a dial indicator to measure it, but its that hard to tell how much it moves.

Have you seen the thread by SAString: http://www.jeepkj.com/forum/f196/mission-50mph-rumble-63431/index8.html Lots of great stuff in there about diagnosing these issues, and the end of the thread is SAS removing the harmonic damper from his driveshaft. Definitely worth a read.
 

arielflash

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I checked mine and I have a small amount of movement here as well, but very small. Hard to tell if it is the spline or the output shaft, but it is not sloppy movement and parallel to the axis of the shaft. I don't have a dial indicator to measure it, but its that hard to tell how much it moves.

Have you seen the thread by SAString: http://www.jeepkj.com/forum/f196/mission-50mph-rumble-63431/index8.html Lots of great stuff in there about diagnosing these issues, and the end of the thread is SAS removing the harmonic damper from his driveshaft. Definitely worth a read.

Thanks! much appreciated...
I am not sure whats considered small/large movement but it does feel mine is not small :\
and another friend with a libby just checked and said no movement at all on his ...

Yeah I have seen that thread... my harmonic damper is still there but before I remove it I wanted to first check if the play is ok or not...
 

mrlavalamp

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It is pretty quick to remove the rear driveshaft. Then you can get ahold of the output shaft directly to see how it feels by itself.

Also, I went looking through the manual and it seems that you can get a fair bit of diagnosis from the outside if you remove the seal here (manual shows a special tool required though). You should be able to see the bearing behind it with the seal out of the way, and getting a look at it end on while you try to move it could show you if this bearing is sloppy. If this bearing is not sloppy, the shaft will stay perfectly concentric in this opening, and it will act like a lever moving the bearing internally (the one you can't see without complete disassembly).

Not sure if you have the factory service manuals, but they are easy to find and free if you google for it. They have some sections regarding diagnosis of various issues as well, but I could not find any spec about the amount of play allowed in this output shaft.

It looks to me like a bearing failure on this shaft would most likely be followed by a seal failure shortly after, causing a leak. The bearing could also seize and then you are wearing the shaft/housing, but less likely and would probably be MUCH more noisy(grinding).

If it is a bearing, you may have caught it early enough before the seal goes, which is good because you can do your best to stop the collateral damage from driving the price to repair up.
 

SAString

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It may sound strange, but I hope it is the bearing. It's the one thing I have suspected, but not replaced after thousands of $ of suspected parts and systems elsewhere.

I have asked this forum if it is possible that the Transfer case could be the issue, but no replies. I have moderate play in that output shaft also. It's no wonder due to the leverage the driveshaft has on it. Please let us know the status and where to find instructions on replacing that bearing, hopefully without removing the transfer case!
 

SAString

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It's not the output bearing! I spent $150 on parts and the better part of day. Learned a lot, but still feel the slight vibes peak around 53mph under load. My wife can't feel what I'm talking about. I think she wants me to give up.... Nah!
 
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SAString

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The parts were not very easy to get at the auto parts chains. The numbers listed for the Bearings and Seal were incorrect (The 206 bearing is too small !)

After 2 returns, I decided on the dealer, since I couldn't find the Oil Slinger anywhere inside of 3 working-days for shipping.

Here are the part numbers I needed for my NP231J (Mine does not have the speedo hole)

attachment.php


HELP ! I totally missed the opportunity to check something while I was changing the bearing. Given the shaft movement, something else is happening. I noticed the bearing isn't required to be pressed in. BUT I DIDN'T NOTICE IF THE BEARING ITSELF WAS LOOSE IN THE HOUSING! It just slid right in place. This could be what has loosened up over time. If someone else knows or does this job sometime in the future, please report if the bearing could be wobbling in the housing. Thanks!
 

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