Chasing a chain dragging noise

[boganst]

I have been chasing this noise for a while... sounds like a chain dragging under my seat. Was told it might be the front drive shaft, so I removed it and have been driving like that for a while. However, I can still hear the chain dragging noise. Seems be mostly in 3rd or 4th when I don't have any torque going on... like coasting or shifting up too early and having to wait for the speed to catch up to the gear. I have also noticed that when I push the clutch in the chain dragging noise goes away.

At first I thought it might be my transfer case chain, but the clutch causing it to disappear has me questioning that. I've read it could be a throw out bearing... which looks like a lot of fun to get to. Wondering if anybody has any other thoughts or ideas before I start taking stuff apart.

Thanks!

 

[JKP]

With the front DS out, the chain isn't turning in 2WD.

The TO bearing only turns when you push the clutch in if everything's working correctly.

 

[boganst]

Alright. Well that sounds opposite than what I have going on as the noise is going on when I am not pushing the clutch in. I'm going to try a transmission fluid exchange and see where that takes me. I have not changed it out since I purchase the jeep.

 

[GoldenGorilla]

Your profile picture looks like you have some lift on the jeep. Do you know what your rear driveshaft angles are? Usually a driveshaft angle issue shows up as a binding/vibration at low speed, but not always. I had a wooshing and sometimes buzzsaw like sound coming up from the rear through the drivetrain only above 60mph which I thought was caused by gears I'd installed. Could be similar to your chain noise. That's not normally the description for a rear driveshaft too steep, but that's what I got. 10 degrees is the max angle at a U-joint and less is better. Tom Woods has a video explainer.

A T-case skid drop kit solved mine for now, though I'll change to a double cardan rear driveshaft at some point. I have a 2.5" lift on an 04 Rubicon with a Barnes no-lift transfer case skid. TJ Rubicons have a different transfer case and rear driveshaft setup from the other TJs. Typically 2.5" lift doesn't have issues with the driveshaft angle in a TJ but the skid and lift combined were just enough to cause a problem for me.

Good luck.