Transfer case squeaking noise only in 2WD

[DMP25-06]

I am a new member to the forum .

I have a 1997 Wrangler Sport , 4.0L , Manual 5 speed transmission with a NP 231J transfer case , pure-stock equipped other that 31x10.50x15" tires . Current mileage is 274,730 .

When releasing the clutch and vehicle begins moving , there is a squeaking noise that sounds like dry , worn-out u-joints , but noise only happens in 2 wheel drive . when transfer case is shifted into 4 wheel drive , the noise does NOT occur .
I first presumed that the u-joints were bad (considering the mileage on the vehicle), so I replaced the u-joints on both rear and front drive shafts , and both axle-shaft u-joints .
Then I drove the vehicle again , and still had the same noise when beginning to move forward from stops . So , again I shifted the transfer case into 4 wheel drive , and the noise stopped when beginning movement from stopped position .

Next , I removed the front drive shaft from the vehicle , and did a test-drive .

With only the rear driveshaft in place , the noise was still present when beginning movement from stops , with transfer case in 2 wheel drive position . However , when I shifted the transfer case into the 4 wheel drive position , the noise was not occuring when movement began .

I am certain that the squeaking noise is within the transfer case , I think that maybe a bearing or bushing that supports the gear-shaft is bad , but I have never opened to inspect or rebuilt a transfer case , and I can't locate a detailed diagram of the internal components of the transfer case .
I really don't want to buy a new or rebuilt transfer case if possible .
Do any of you have experience repairing/rebuilding the NP 231J transfer case ?

Thank you for any help that you offer .
DMP25-06

 

[hear]

I am a new member to the forum .

I have a 1997 Wrangler Sport , 4.0L , Manual 5 speed transmission with a NP 231J transfer case , pure-stock equipped other that 31x10.50x15" tires . Current mileage is 274,730 .

When releasing the clutch and vehicle begins moving , there is a squeaking noise that sounds like dry , worn-out u-joints , but noise only happens in 2 wheel drive . when transfer case is shifted into 4 wheel drive , the noise does NOT occur .
I first presumed that the u-joints were bad (considering the mileage on the vehicle), so I replaced the u-joints on both rear and front drive shafts , and both axle-shaft u-joints .
Then I drove the vehicle again , and still had the same noise when beginning to move forward from stops . So , again I shifted the transfer case into 4 wheel drive , and the noise stopped when beginning movement from stopped position .
Next , I removed the front drive shaft from the vehicle , and did a test-drive .
With only the rear driveshaft in place , the noise was still present when beginning movement from stops , with transfer case in 2 wheel drive position . However , when I shifted the transfer case into the 4 wheel drive position , the noise was not occuring when movement began .

I am certain that the squeaking noise is within the transfer case , I think that maybe a bearing or bushing that supports the gear-shaft is bad , but I have never opened to inspect or rebuilt a transfer case , and I can't locate a detailed diagram of the internal components of the transfer case .
I really don't want to buy a new or rebuilt transfer case if possible .
Do any of you have experience repairing/rebuilding the NP 231J transfer case ?

Thank you for any help that you offer .
DMP25-06

They're pretty easy to open, although you will need a set of lock ring pliers (not to be confused with snap ring pliers). There's not a ton of stuff going on inside them, honestly. Watch any video on doing an SYE job, the steps will be identical except for the new output shaft & housing. Bleepin Jeep has a very good video on this.

I can't speak to your problem, but I'm not aware of anything that is in use in 2WD that isn't also in use in 4WD. But maybe the noise is a result of something NOT being under load in 2WD that when loaded the noise goes away. No idea what that would be.

 

[DMP25-06]

They're pretty easy to open, although you will need a set of lock ring pliers (not to be confused with snap ring pliers). There's not a ton of stuff going on inside them, honestly. Watch any video on doing an SYE job, the steps will be identical except for the new output shaft & housing. Bleepin Jeep has a very good video on this.

I can't speak to your problem, but I'm not aware of anything that is in use in 2WD that isn't also in use in 4WD. But maybe the noise is a result of something NOT being under load in 2WD that when loaded the noise goes away. No idea what that would be.

Thank You Sir.

 

[machoheadgames]

Yeah, similar to above I can’t really think of anything that moves in 2wd in a way that would make noise that either stops moving in 4wd or changes how it moves that the noise would go away. Maybe it’s a load issue.

The only difference between 2hi and 4hi is the fork locking the chain sprocket to the main shaft. But even in 2hi, all that stuff is spinning anyways since the front axle is fully live and the front wheels turning means the driveshaft is turning. So that is a very odd problem to have for sure.

They are pretty easy to rebuild if you wish to explore that option. Just need to watch some YouTube videos and get a good set of lock ring pliers.

 

[TJ Jim]

I did not see that you pulled the rear drive shaft? Pull the rear and drive it in 4wd to see if the rear drive shaft is your squeak.

 

[DMP25-06]

But maybe the noise is a result of something NOT being under load in 2WD that when loaded the noise goes away. No idea what that would be.

I would guess that the transfer case chain and drive-sprocket is spinning at all times , since my Wrangler does NOT have lock-out front hubs .

I presume that there is a bad bearing or bushing that supports the main shaft of the transfer case , possibly allowing slight wobble of main shaft that creates the squeaking noise . When I shift into 4WD , the gear assembly that engages the chain drive-sprocket is moved into a position that supports the main shaft , stopping the squeaking noise .

I have not been able to locate information that I can study that will help me .

It may be several weeks before I can remove the transfer case to disassemble and repair it , due to my age -74- and health condition .
My son will have to lift transfer case from rear of transmission .

I will post what I find inside the transfer case that is causing this noise , and what will be necessary to correct the problem .

I may be totally wrong in my thoughts about the inner-working of the transfer case , and if I am not correctly envisioning the main shaft and gearing interaction , please correct me .


Thank You ,
DMP25-06