Noise Isolation Help

FishFam JKU

FishFam JKU

JK Enthusiast
Joined
Jun 22, 2021
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120
Location
Livermore, CA
Yet another random noise from the 08' JK Rubicon.

I can't isolate and identify it but looking for steps to do so. Sound comes at temperature at all speeds. Moves with speed regardless of gear (automatic). Both diffs had fluid changed within the last 3k miles. No sign of excessive wear in the fluid. Yesterday I pulled the front drive shaft and been running 2wd. Now I can't replicate the noise. I have yet to run the T-Case in 4wd with the shaft off but not sure if that would identify anything?

Drive shafts are Reels and is in good shape, u-Joints all appear to be in good shape.

The only thing that keeps coming to mind is the Front Output bearings on the T-Case but I don't want to tear into that beast if I don't have to. Any way to narrow down the front/rear pinons, T-case or Transmission?

Thanks

Scott
 
I would think if the front output bearing is bad it would possibly be leaking from the seal. If you do run it in 4wd with the shaft off and it is the bearing it should still make a noise.

Could you possibly have bent the front driveshaft or knocked a balance weight off?
 
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BLACKJKU said:
I would think if the front output bearing is bad it would possibly be leaking from the seal. If you do run it in 4wd with the shaft off and it is the bearing it should still make a noise.

Could you possibly have bent the front driveshaft or knocked a balance weight off?
Click to expand...
Possibly, but it just popped up the last few days and nothing but street driven lately. No leaks visible.
I'll warm her up and pop it into 4wd (shaft off). We'll see if I can narrow it more. Thanks.
 
FishFam JKU said:
Yet another random noise from the 08' JK Rubicon.

I can't isolate and identify it but looking for steps to do so. Sound comes at temperature at all speeds. Moves with speed regardless of gear (automatic). Both diffs had fluid changed within the last 3k miles. No sign of excessive wear in the fluid. Yesterday I pulled the front drive shaft and been running 2wd. Now I can't replicate the noise. I have yet to run the T-Case in 4wd with the shaft off but not sure if that would identify anything?

Drive shafts are Reels and is in good shape, u-Joints all appear to be in good shape.

The only thing that keeps coming to mind is the Front Output bearings on the T-Case but I don't want to tear into that beast if I don't have to. Any way to narrow down the front/rear pinons, T-case or Transmission?

Thanks

Scott
Click to expand...

You mentioned the diffs but did you check the transfer case fluid?
 
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You removed the front drive shaft and the noise went away- that's a clue.

My brother had a noise in his '09 that was driving him crazy. Turned out to be the Rzeppa joint (fancy word for Constant Velocity) end of the drive shaft, the end connecting to the T case. He fixed it by replacing the factory drive shaft with an Adams double cardan drive shaft.

Just consider the factory drive shafts as place holders for real drive shafts.
 
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Finally getting parts and time. I’ll finish the rebuild of the front driveshaft tomorrow and throw it in. I don’t believe that is the source but U-Joints definitely needed a redo.

Got the T-case kit ready to go if needed next.

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Front drive shaft is back in… And no noises. I’m at a loss unless it was a bad u-joint. The ones I removed were still in good shape and would not expect any noises or failures.

With no noise to chase I’m playing a waiting game of “what fails first?” Very expensive game. With only a few weeks until my trip to Utah I’m running short on time to rebuild anything.
 
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FishFam JKU said:
Front drive shaft is back in… And no noises. I’m at a loss unless it was a bad u-joint. The ones I removed were still in good shape and would not expect any noises or failures.

With no noise to chase I’m playing a waiting game of “what fails first?” Very expensive game. With only a few weeks until my trip to Utah I’m running short on time to rebuild anything.
Click to expand...
My brother went through the same thing. He had a noise and spent a lot of time and money chasing it down. He replaced the U-joints in both front axle shafts, both front wheel hubs and went through his entire steering system. Still had a noise, a clunk. Turned out to be the Rzeppa joint in his front driveshaft. He replaced his front driveshaft with a double cardan driveshaft from Adams. No more clunk.

His Jeep did need the new U joints and wheel hubs, so it wasn't a waste of money or time. But I'm not surprised that the problem was your drive shaft.

I recently bought a 2012 Wrangler Rubicon and the U joints were badly worn. I was gonna have the U joints and the Rzeppa joint replaced with a high flex unit from Terra Flex, but instead went with an Adams driveshaft. So far, the Adams driveshaft is working great. No driveline vibration and it's good for stock suspensions and up to 4 inches of lift. My brother lives near an ORV park and goes wheeling with his Rubicon nearly every weekend. His Adams driveshafts are holding up well
 
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