strange clanking sound after offroad trip

nmwranglerx

nmwranglerx

Caught the Bug
Noticed a strange clanking/knocking sound coming from underbody of jeep, seems to be from rear and happens when I take foot off gas pedal. I don't feel any vibrations through steering and jeep seems to drive normal. Here's a video, happens at about 19 seconds in when I let off the gas, any ideas? I didn't have time to mount gopro on other side of rear axle to see what driveshaft is doing because a storm came up and I lost light but I will in the next day or so...

 
Moochie said:
Maybe a blown CV joint? Or a chipped ring gear? Sorry, just guessing.
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Thanks for suggestions, I know it's kinda hard to say from just looking at video, I really hope it's not ring gear, didn't think we were playing on rocks that hard
 
GulfCoastJeeper said:
Sounds like a drive shaft u joint going. Do you have a vibration at any speeds?
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No vibrations up through about 30 mph, I've been nervous to take it above that. I could live with replacing the driveshaft, a chipped ring gear would be a real bummer.....I'll have more time to diagnose this weekend, shoot some more video from middle to rear of jeep and pull diff cover to inspect gears
 
When my front u joint on the shaft was going u just had a vibe from 60-70 miles per hour and made a similar sound to yours as I was coming off the gas to stop. Which makes since because that's when there wasn't a load on the shaft anymore so it can clank due to the "slop" in the joint. I wouldn't think ring gear. That would be present at all speeds and increasing in frequency as speed increased I would think.
 
GulfCoastJeeper said:
When my front u joint on the shaft was going u just had a vibe from 60-70 miles per hour and made a similar sound to yours as I was coming off the gas to stop. Which makes since because that's when there wasn't a load on the shaft anymore so it can clank due to the "slop" in the joint. I wouldn't think ring gear. That would be present at all speeds and increasing in frequency as speed increased I would think.
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thanks for the input:thumb:.....the OEM JK rear driveshaft uses CV joint but could still be the issue I suppose....perhaps video will show or I can pull shaft and drive it to see if sound goes away...
 
I see you got a 4" lift kit and the factory drive shaft. I read multiple time here that the factory DS will not last long with 4"+ lift.

Beside, if it would be a gear wouldn't it be more of a problem when accelerating that letting go the pedal?

Looking forward to see the problem ! Good luck :rock:
 
Honestly I would Check your Control arms and Sway Bar end Links.

The Heims on the End Links can go bad and make some weird noises. The ones on my Front Are going bad, and when I checked them they were loose, and the next day the were not. It all depends on the Pressure of the Jeep on them.

Control arms could be a possibility if the sound is when you are changing acceleration. With the Body Shifting front to back you can get some mean Clunky noises. I had that when my Rear uppers blew out at the Frame end. When i would Slow down or stop you could hear them shift.

Just some ideas
 
Thanks for all the input. It's been busy at work, so I won't have a chance to check til weekend. I'll re-torque control arms, I recently unbolted to grease zerks. I'll post what I find
 
Ok, had a chance to diagnose some more this morning. Rear upper control arm bolts were a little loose BUT the main culprit turned out to be VERY loose lug nuts on rear driver side. I feel pretty stupid for overlooking obvious and having just come off our road trip from Sedona at high freeway speeds very lucky. I'm usually pretty anal about routine stuff but man somehow missed this or somebody wants me dead. Lesson learned, check your lug nuts boys and girls
 
nmwranglerx said:
Ok, had a chance to diagnose some more this morning. Rear upper control arm bolts were a little loose BUT the main culprit turned out to be VERY loose lug nuts on rear driver side. I feel pretty stupid for overlooking obvious and having just come off our road trip from Sedona at high freeway speeds very lucky. I'm usually pretty anal about routine stuff but man somehow missed this or somebody wants me dead. Lesson learned, check your lug nuts boys and girls
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Lol, had a similar problem not long ago. I was feeling that little strange vibration right under my ass (yeah... no kidding) but didn't feel anything unusual on my steering. So when I came back home checked all around. Happened that I broke a rear wheel stud and was able to unscrew all other 4 nuts with my bare hands.


Well, what made me freak out the most was the cost for a new stud... 25$ :eek:

So yeah, now I check these frequently. Lesson learned !
 
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