Please help me - what's causing my drive shaft to make this noise shifting out of 4lo

T

tylerbrinks

Member
I have a 2017 automatic JKUR which has had a CV drive shaft for about 3000 miles. Just recently I've been getting this ringing noise when I shift from 4lo back to 4hi. The sound is almost certainly coming from the drive shaft because:

  1. Tapping the drive shaft's body with a wrench yields the exact same sound.
  2. I removed the drive shaft from the t-case and the noise doesn't happen when it's disconnected.

Here's a short video shifting from 4hi to 4lo demonstrating the issue:

https://streamable.com/s/uu6ro/lsdktp

For what it's worth, it also happens occasionally when shifting from Park to Reverse or from Drive to Reverse.

I can't tell if it's a problem with the T-Case, the drive shaft, or something else in the drive line. I really need some good advice or ideas on this one. Thanks a million for the help!!
 
tylerbrinks said:
]I removed the drive shaft from the t-case and the noise doesn't happen when it's disconnected.
Click to expand...

I can't watch the video at the moment, but this alone makes me think it's a u-joint on the driveshaft that has play.
 
JKDream said:
I can't watch the video at the moment, but this alone makes me think it's a u-joint on the driveshaft that has play.
Click to expand...

If it helps, the joints are the Spicer Life type that don't require grease. They have about 3K miles on them, but that doesn't mean one of them hasn't kicked the can already.
 
JKDream said:
I can't watch the video at the moment, but this alone makes me think it's a u-joint on the driveshaft that has play.
Click to expand...
No, that's definately not a u-joint. Watch the video. Idk. Nothing to add but I think is has something to do with the transfer case. Yikes, that doesn't seem normal at all!

sent from SPACE!
DZZ Build thread
 
When I installed the new driveshaft that came with my mopar kit, they supplied a rubber star washer that went under the new yoke, part# 4210973, maybe it helps lower the vibration from initial shift. ???


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JKbrick said:
Is the trans in drive or neutral in this video? Can’t say I’ve ever seen this before
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Trans is in neutral the same way you'd typically shift in and out of 4lo. When you hear the sound, it's going from 4lo to 4hi. The sounds is right when it clears the t-case neutral and engages the 4hi gear set
 
Faulka28 said:
When I installed the new driveshaft that came with my mopar kit, they supplied a rubber star washer that went under the new yoke, part# 4210973, maybe it helps lower the vibration from initial shift. ???
Click to expand...

The yoke reused the rubber o-ring that the stock yoke uses and it sits under the nut. That's the norm for most CV installations on a JK. Nothing fancy there, and not really vibration related; more for creating a seal.
 
If I were you, have a helper do the action to make that symptom occur while you are underneath with a stethoscope. I have been working in shops for about 20 years and have never heard something like that. Almost sounds like something is thousands of an inch from touching something else, and that slight movement causes the objects to touch and resonate. Check skid plate clearances also.
 
DWiggles said:
No, that's definately not a u-joint. Watch the video. Idk. Nothing to add but I think is has something to do with the transfer case. Yikes, that doesn't seem normal at all!
Click to expand...

What's strange is that the sound resonates in the shaft. I can tap it with a screw driver and it sounds the same. That suggests something has to be impacting the shaft, right? The only moving parts outside of the t-case are u-joints. So, what about something internal to the t-case sending an impact down the drive line? Like the shift fork being out of whack? I wonder if an impact happening inside the t-case would send a shock into yoke and, since there's no play at all in the yoke or joints, causes the shaft to compress front to back..??
 
tylerbrinks said:
What's strange is that the sound resonates in the shaft. I can tap it with a screw driver and it sounds the same. That suggests something has to be impacting the shaft, right? The only moving parts outside of the t-case are u-joints. So, what about something internal to the t-case sending an impact down the drive line? Like the shift fork being out of whack? I wonder if an impact happening inside the t-case would send a shock into yoke and, since there's no play at all in the yoke or joints, causes the shaft to compress front to back..??
Click to expand...

Hold the tcase end of the shaft tight with your hand on the tcase side of the ujoint and hit the shaft again. See if noise is still there. If it is, keep moving your hand down the shaft (no homo) and see if noise eventually goes away. Look at the weight on the driveshaft and make sure both welds are in tact. If one weld is cracked, that may be the issue, just enough to cause resonating noise.
 
WJCO said:
Hold the tcase end of the shaft tight with your hand on the tcase side of the ujoint and hit the shaft again. See if noise is still there. If it is, keep moving your hand down the shaft (no homo) and see if noise eventually goes away. Look at the weight on the driveshaft and make sure both welds are in tact. If one weld is cracked, that may be the issue, just enough to cause resonating noise.
Click to expand...

I just crawled under my jeep and did precisely what you outlined. First, grabbing it about 14 inches from the yoke totally muffles any noise whatsoever. I tried see if one of the weight's welds were broken, but there's no weight on it. I had to do a triple check on that because I don't remember if it had one when it was fabricated. It seems smooth from the CV to the stub, no signs of the weight having broken off that I could feel. The front shaft has the weight welded to the pinion side, so naturally I triple checked the pinion side on the rear. No weight there either. It would be shocking for a shaft to be so balanced that it needed no weight, but maybe that's the case. Sure makes me feel like I need to go show the guy who fabricated the shaft since he's local and it's under warranty...
 
WJCO said:
Hold the tcase end of the shaft tight with your hand on the tcase side of the ujoint and hit the shaft again. See if noise is still there. If it is, keep moving your hand down the shaft (no homo) and see if noise eventually goes away. Look at the weight on the driveshaft and make sure both welds are in tact. If one weld is cracked, that may be the issue, just enough to cause resonating noise.
Click to expand...

I actually took the t-case side of the rear drive shaft off to inspect everything. I even had the drive shaft's fabricator take a look at it (while bolted on) this morning. Everyone agreed that the t-case seems like the issue, not the drive shaft. The noise is clearly coming from the drive shaft as you can see in the short clip (linked below) when the CV housing come into contact with the recess of the drive shaft's ears. But the u-joints are tight enough and have full range of motion. I still don't think it's the drive shaft that's causing the issue, but that it's simply highlighting an underlying problem.

https://streamable.com/n4o73

The other interesting fact is that when the parking pawl engages when I park on an incline, the same noise happens when I go from park to reverse, even in 2hi. It's like something in the t-case is building up torque and releasing it through the drive line and causing the noise.

Finally, t-case is so darn hard to get back into 4hi from 4lo regardless of whether the Jeep is slowly rolling or at a stand still, and that wasn't the case when it rolled off the dealer's lot a year ago. It's also a bit tricky to get it to stay in 4lo - it likes to pop back to neutral unless you give the shifter a bit of encouragement. All that seems to point to a problem buried in the t-case, which is beyond my mechanical aptitude. The good news is it's under warranty, so I'm having the dealer's service department look at it next week.
 
DWiggles said:
No, that's definately not a u-joint. Watch the video. Idk. Nothing to add but I think is has something to do with the transfer case. Yikes, that doesn't seem normal at all!

sent from SPACE!
DZZ Build thread
Click to expand...
Just watched the video finally. Bit confused honestly. I accidentally had my transfer case in neutral awhile ago while working on the truck, and threw it into drive and grinded some gears. Ever since it's made a similar noise going from park to reverse or drive, but only when the vehicle has sat for awhile. Unfortunately I've never figured it out. Reasoning behind the u-joint though was - I had a cap work its way loose on one of them, and every time I threw it into drive it would turn the driveshaft just enough for the u-joint to contact the ears on the yoke and make a pinging noise. But that doesn't seem like the case here.

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wayoflife said:
Does still make the same sound when your engine is off?
Click to expand...

Hi Eddie! I've never tried shifting in our out of 4hi/lo with the engine off. I'm happy to give it a try and see, but it sounds entirely mechanical so I'd assume so. I'll give it a try when I run out for lunch in an hour.
 
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