My turn: axle u-joint?

Zorba

Zorba

"The Veiled Male"
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I parked my Jeep 2 days ago - no issues. Drove it out today, and am getting an odd vibration. Starts subtly around 16 MPH, peaks between 20 and 24-ish, then tapers off and is gone by the time I reach 30. It feels pretty much like driving over a mild washboard, seems to be coming from the front right, and only under acceleration. That combination doesn't make sense to me, but that's what its like. I tried shifting into 4 hi briefly, and it SEEMED to help it dampen down - but its hard to tell for sure.

I also heard and felt a one time BANG! that's consistent with a loose control arm - so I certainly need to check those (again).

But any other clues would be appreciated. I wiggled both drive shafts and they seem to be fine - they're not loose at least. Any tips for checking the Axle U-joints? Checked air pressure too.
 
When I started getting some vibes and an occasional pop/click/bang it ended up being my wheel bearing/hub…

It progressively got worse over a short period of time until it started really sounding crunchy. I was driving a lot of daily miles though…
 
I bit the bullet!
Hit the bank account and replaced wheel hubs, u-joints, upper and lower ball joints, tie rod ends, rebuild front diff. and front drive shaft.
Sings along the interstate at 75 like a dream.
 
Check for ball joint and wheel bearing play too. Mine felt loose and shook slightly when fully turned and when backing out of parking spaces. I let it go for weeks, until I could visibly shake the u-joints (not recommended). I replaced everything to avoid it being taken apart again when something else went bad.
 
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Zorba said:
I parked my Jeep 2 days ago - no issues. Drove it out today, and am getting an odd vibration. Starts subtly around 16 MPH, peaks between 20 and 24-ish, then tapers off and is gone by the time I reach 30. It feels pretty much like driving over a mild washboard, seems to be coming from the front right, and only under acceleration. That combination doesn't make sense to me, but that's what its like. I tried shifting into 4 hi briefly, and it SEEMED to help it dampen down - but its hard to tell for sure.

I also heard and felt a one time BANG! that's consistent with a loose control arm - so I certainly need to check those (again).

But any other clues would be appreciated. I wiggled both drive shafts and they seem to be fine - they're not loose at least. Any tips for checking the Axle U-joints? Checked air pressure too.
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I'd jack up the front-right tire and rotate it back & forth with some force while watching the axle shaft u-joint. Is the trunnion (body) moving inside the bearing cap while rotating the tire hard back & forth? Any rusty dust coming out of any of the u-joint's bearing caps?
 
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Jerry Bransford said:
I'd jack up the front-right tire and rotate it back & forth while watching the axle shaft u-joint. Is the trunnion (body) moving inside the bearing cap while rotating the tire hard back & forth? Any rusty dust coming out of any of the u-joint's bearing caps?
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Thank you. @NWPA Jeepy T 's claim that it was a rear driveshaft problem make sense to me as well as the vibration only occurs under acceleration. The rear driveshaft seems to be pretty tight, but would the vibration exhibit the "only on acceleration" if it were a front axle U-joint? The two seem to contradict each other - but maybe my butt is out of calibration and the vibration isn't coming from the front. OTOH, there *was* that bang from the front... I'm confused, but what else is new?

Regardless of all that, I'll check the front as you explained.
 
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Zorba said:
Thank you. @NWPA Jeepy T 's claim that it was a rear driveshaft problem make sense to me as well as the vibration only occurs under acceleration. The rear driveshaft seems to be pretty tight, but would the vibration exhibit the "only on acceleration" if it were a front axle U-joint? The two seem to contradict each other - but maybe my butt is out of calibration and the vibration isn't coming from the front. OTOH, there *was* that bang from the front... I'm confused, but what else is new?

Regardless of all that, I'll check the front as you explained.
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My rear driveshaft seemed tight until I got started removing the cap bolts and all the rusty needles fell out of one of the caps
 
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Next stupid question: Can I remove the rear driveshaft and test drive the Jeep? I seem to recall something about oil coming out of the xfer case if you try that? *shrug*

Tried checking the front axle U-joints - no play observed even when I wedge the axle side with a screwdriver.
 
Zorba said:
Next stupid question: Can I remove the rear driveshaft and test drive the Jeep? I seem to recall something about oil coming out of the xfer case if you try that? *shrug*

Tried checking the front axle U-joints - no play observed even when I wedge the axle side with a screwdriver.
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The TJ 231 transfer cases don’t have that problem like the YJs did. You can remove the rear TJ driveshaft and drive on the front without issue…
 
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@NWPA Jeepy T Nailed it - its the forward rear driveshaft u-joint. But not to leave @Jerry Bransford out, driving the jeep in FWD, makes me believe the axle U-joints are bad as well, there's a kind of ratcheting motion on sharp on-pavement turns (read: Parking lots). The driveshaft removal was as easy as everyone said it was - so easy even a Belly Dancer can do it!

I actually ordered a complete new set of U-joints last nite as I figured that even if it turned out to not be the problem, they were due to be replaced anyway. I bought Jerry's recommended greasable DuraLast brand from AutoZone. ;)

The CarFAX for this Jeep noted that "driveshaft u-joint(s)" were replaced at some point - wonder if I'll be able to figure out which one(s). I covered the xfer case output shaft with electrical tape to protect it until the U-joints come in and I can get them installed. I'm still trying to put this house back together from the re-pipe job, AND to make the end phase of this barely-passed Mercury Retrograde complete, wife's car had a cooling fan go out, so until I got that driveshaft out of the Jeep, we were down to one car! That fiasco killed both my monthly facial as well as my Thursday nite dance class.


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Zorba said:
Dumb question: Does the front to back orientation of the driveshaft matter? I marked it, but want to know...
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The CV joint end goes closes to the transfer case. That's toward the rear since you don't know where the transfer case is. 🤣
 
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