OK - need some help diagnosing possible causes of a noise. It has happened last couple times going off road but is intermittent (maybe 50% of the time it's there and 50% it isn't), sounded like it's from the front driver wheel so I have taken that all apart, replaced the U Joint, checked that everything else is tight and in good condition. That didn't fix it so I drained front diff (stock D30 axle, no locker) and examined inside. It all looks fine, no chunks/flakes of metal, nothing appears to be bent/broken in there. Spent some time today trying to work out exactly when it happens. It is only when in 4WD (4H or 4L). Never in 2WD. It's speed related, and worse in reverse than it is in forward. Seems to happen more when turning than when straight.

You can hear it clearly in the poorly filmed youtube video below.....
https://youtu.be/k00c-9pLI1M

Any ideas on which parts I should investigate next - thanks, Alan

 

Wow, that's definitely not normal. Only in 4 wheel is suspicious since the JK is always locked at the hubs, so the front gears and axle shafts are always spinning (and drive shaft). That would indicate the t-case could be involved.

This will be an interesting thread.

 

I figured it may be that in 4WD things are under way more stress as it's being driven from the Tcase, whereas in 2WD it's just all turning because the wheels are turning.

 

Do you still have the stock driveshafts? I had a similar noise on mine that only occurred while in 4WD and turning (everything is more bound up in that scenario) and it turned out to be the front driveshaft.

I'd crawl under your Jeep and see if there is any play in your front driveshaft, since its only happening in 4WD. Mine had a decent amount of play in the rezeppa joint at the transfer case.

 

yes - still running stock driveshafts F&R. i have a Metalcloak 3.5" lift, so they are maybe a little strained - plus they've been dragged over some rocks pretty badly. i'll crawl under tomorrow and I am also going to rig up the video camera underneath so I can some better video/sound that may help. thanks!

 

I would check the boot on your cv joint. With that much lift it can contact the frame and tear the boot. If that is the case it will be time for new driveshafts that will clear the frame.

 

Just pull the front drive shaft. Drive it in 4wd and see if it still does it. That will quickly help narrow it down.

 

If it only does it in 4WD, then removing the front driveshaft doesn't necessarily narrow it down. :P

 

Why is that? If it still does it, it's not the drive shaft or front axle related.

 

Yup jks have no manual hubs so to rule out shaft and front axle potentially you can pull the shaft...