Need help with a noise

[bbaldwin237]

So I spent two days running trails and cannot figure what this noise is. In the video I start in 4L and you can hear the noise. The first shift is into 2wd and no noise. Then I shift into 4H and the noise is back.

I have checked every joint on the driveshafts and don't see anything obvious with the u-joints and there are no marks anywhere to indicate metal to metal contact. There is a ujoint in the front short side axle shaft that is greasy and collecting dust but still appears tight and not causing any issues. 4wd and lockers both work fine and the Jeep performed as expected on the trails. The noise stayed consistent with rpm but seemed to go away and was unable to be heard at slightly faster speeds.

Also, it sounded like it was coming from directly under me or behind.

View: https://youtube.com/shorts/0aF60nU11iw?is=XUxKtum4o4dOjGoD

 

[Feralkid]

Could the transfer case shift linkage have gotten bent and be rubbing on the front drive shaft yoke when it's in 4WD?
Do you have a body lift? Does it make the noise when your rolling with the transfer case in neutral?

 

[bbaldwin237]

Could the transfer case shift linkage have gotten bent and be rubbing on the front drive shaft yoke when it's in 4WD?
Do you have a body lift?

Have a body lift and Savvy cable shifter. Everything shifts smooth. I actually adjusted the shifter on the trail the other day to see if it was partially engaging. That didn't change anything. This video was actually after the adjustment. Then that actually didn't make sense because it does it in 4H too and there's nothing that would cause a partial engagement in 4H because there's no consoles or metal to limit the travel of the shifter.

I probably should have added in the first post, I have a 4+1.25 lift, mml, "tummy tuck" +1" skid, sssye, Adam's rear driveshaft, adjustable CA's....the standard forum 4" recipe. Gears and shafts are Yukon, lockers are ARBs.

 

[Feralkid]

Transfer case might need rebuilt. Pull the front drive shaft and see if it goes away.

 

[bbaldwin237]

The transfer case is one of my thoughts. I replaced the chain when I did the SSSYE and everything else seemed fine. I can't figure what could be in there causing this noise.

I was also wondering if it could be a cardan joint, but the front driveshaft spins in 2wd so that doesn't seem like it would make sense to me. Which brings me back to the t-case, but again, still confused on what could make the noise. I know that I may not have an answer until I get inside, but hoping someone has had a similar experience.

Also, for what it's worth, I checked all fluid levels and everything was good. No indication of metal flake in diffs or t-case.

 

[Feralkid]

I was also wondering if it could be a cardan joint, but the front driveshaft spins in 2wd so that doesn't seem like it would make sense to me.

In 2WD there's no torque being delivered. It may be a u joint that is worn only enough to have problems while under torque.

 

[bbaldwin237]

In 2WD there's no torque being delivered. It may be a u joint that is worn only enough to have problems while under torque.

But there's no additional torque in 4H as that remains the same 1:1.

It'll be a bit before I can pull the front driveshaft because I've got to work all week and then I'm heading out of state on a trip next weekend. Just wanting to have some ideas of where to start when I can get to it. I don't want to be down too long!

 

[Feralkid]

But there's no additional torque in 4H as that remains the same 1:1.

In 2WD the front drive shaft and axles are turned by the wheels, in 4WD they're turned by the engine against the resistance of the wheels.

 

[JMT]

My first thought was something in the TCase, but noises are hard. Lay your phone on the ground and record in slo-mo as you drive over and at least then you can isolate where in the drivetrain it’s coming from. I did that once to identify a u joint as a culprit. Didn't think that could be it because I’d already sent the shaft to Adam’s to rebuild.

 

[bbaldwin237]

My first thought was something in the TCase, but noises are hard. Lay your phone on the ground and record in slo-mo as you drive over and at least then you can isolate where in the drivetrain it’s coming from. I did that once to identify a u joint as a culprit. Didn't think that could be it because I’d already sent the shaft to Adam’s to rebuild.

In 2WD the front drive shaft and axles are turned by the wheels, in 4WD they're turned by the engine against the resistance of the wheels.

If it's something in the front driveshaft I may just use that as an opportunity to replace it with an Adam's.

I'm hoping that it's front driveshaft and not t-case