Np231 Transfer case noise

Anyone have any idea what this noise could be? I put the transfer case together years ago, have zero issues with it other then this noise. I’ve never noticed because it was in a wheeler. Just installed in a Jeep I plan on driving to the trail. Driving 70 mph it sounds horrible in the cab.

It’s got a AA SYE kit and Teraflex 2 low kit otherwise the case is a 23 spline transfer case from a 97 Xj

https://youtu.be/D0NX5yj5D8I

You can get a rough idea of T-Case chain stretch by poking around in both the drain and fill holes at the same time. Inspect drained fluid for aluminum sparkles.

Check that the flex plate is not cracked and the flex plate bolts are not loose.

Tim_MN said:

You can get a rough idea of T-Case chain stretch by poking around in both the drain and fill holes at the same time. Inspect drained fluid for aluminum sparkles.

Check that the flex plate is not cracked and the flex plate bolts are not loose.

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I did already drain the fluid and it’s nice and red, a little silver but nothing I’d consider startling. I’m going to just pull it and see what’s up. I know the bearings were in good shape last time I had it apart which in reality wasn’t very long ago.

This Jeep is also a manual so I know it’s not loose torque convertor bolts. Not a bad idea if it was a auto though. I am 99% positive the noise is coming from the transfer case though.

I’m not convinced it’s your tcase. In your video the Jeep isn’t moving while the motor is running so there shouldn’t be anything happening in the tcase. If you’re hearing the noise while you’re parked with the motor running, I would think that something between you crank shaft and transmission input is causing the noise. Maybe a throw out bearing?


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DocTremp said:

I’m not convinced it’s your tcase. In your video the Jeep isn’t moving while the motor is running so there shouldn’t be anything happening in the tcase. If you’re hearing the noise while you’re parked with the motor running, I would think that something between you crank shaft and transmission input is causing the noise. Maybe a throw out bearing?


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Click to expand...

In that video that’s 5th gear clutch engaged with no driveshafts hooked up. Guess I should have led with that.

Got the transfer case town apart nothing looks damaged, and the bearings look and feel good. However this transfer case originally a 21 spline transfer case that I swapped to a 23 spline input. I know I didn't change the sun gear so that may very well be the problem.



video:https://youtu.be/liJiAbPPIro

Confirmed this noise is from the planetary gear and the sun gear not meshing properly, I ended up getting a new donor transfer case and will swap out all my guts into the case.