Here's a puzzler

[Donkey Fluffer]

I have a JT Rubicon with 4500 miles. 2" Mopar lift with 315/70/17's. All dealer installed before delivery. Has been flawless.

Thrumming noise at 35 mph started today. Roadwayis smooth. Went away in a minute. Came back and went away again. Driving home today it started at any speed, and was mostly constant. Not tires or wheels. Not tranny. No vibrations or shimmy. All gauges read normal. Nothing rubbing. Doesn't matter if going straight or turning. Turned off HVAC controls to see if it was compressor related. It's not. Sounds like its from the front end.

Out of curiosity, shifted to 4High. Noise immediately went away. Drove 2 miles with no thrumming. Went back to 2High. Noise immediately returned. Did this several times. Noise is only in 2High.

Anyone experienced this before?

Going to dealer tomorrow, but wanted to know what's going on. Front diff? Transfer case? Iranians?

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[Renegade]

Hopefully not this:
https://www.jlwranglerforums.com/forum/threads/fad-failure-twice.35114/

 

[Donkey Fluffer]

Thanks. I certainly hope not

 

[ShadowsPapa]

Wow, hope not.......... in 2 wheel drive mode the axle ends in that disconnect area are spinning in opposite direction.
Obviously as anyone here would know, in either 4 mode the axle halves are locked together.

When you have a noise that you can make go away, logic says - "what changes".
That for sure is one thing.
The other is that the carrier side gears - spiders, are no longer spinning inside the carrier when you shift into 4 wheel drive mode (L or H), they are now in effect locked to the carrier.
So you are are changing what's happening inside the differential case, too.
The small gears inside the carrier are spinning when the axle is disconnected, they are not spinning inside the carrier but turn WITH it in 4 mode.

 

[Donkey Fluffer]

Yeah, I'm a bit concerned but glad I could narrow it down. Also kind of glad it wasn't so intermittent that the service manager can't say he couldn't recreate the problem. It's definitely going to be noticeable immediately.

 

[JeepCares]

Yeah, I'm a bit concerned but glad I could narrow it down. Also kind of glad it wasn't so intermittent that the service manager can't say he couldn't recreate the problem. It's definitely going to be noticeable immediately.

We're sorry to learn this! Please connect with us PM if you would like additional support while in service.

Darlene
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[jkuhn1113]

Yeah, I'm a bit concerned but glad I could narrow it down. Also kind of glad it wasn't so intermittent that the service manager can't say he couldn't recreate the problem. It's definitely going to be noticeable immediately.

What happened with this? The opposite happens on mine mine makes an odd noise in 4h when letting off the gas.

 

[Donkey Fluffer]

What happened with this? The opposite happens on mine mine makes an odd noise in 4h when letting off the gas.

Well the jury is still out. Dealer couldn't recreate the noise, but the temps went from below 30° in the morning to 55°. The noise stops after it warms up driving on the cold days, and simply doesn't do it when it's warmer. They checked the diff and transfer and said they were fine

So I have to wait for a cold snap.

 

[ShadowsPapa]

Well the jury is still out. Dealer couldn't recreate the noise, but the temps went from below 30° in the morning to 55°. The noise stops after it warms up driving on the cold days, and simply doesn't do it when it's warmer. They checked the diff and transfer and said they were fine

So I have to wait for a cold snap.

It's not an exhaust rattle is it? The whole drivetrain will react differently when in 4 compared to 2 as far as vibrations, movements on the mounts, and the proximity of the exhaust pipe to the structure below.

 

[dirtlimo]

What happened with this? The opposite happens on mine mine makes an odd noise in 4h when letting off the gas.

Same thing here as well, have not visited the dealer yet but will...

 

[jkuhn1113]

Same thing here as well, have not visited the dealer yet but will...

Think I found the problem... Transfer case seems to be leaking.

 

[dirtlimo]

Think I found the problem... Transfer case seems to be leaking.

Well s#$t...that ain't good...

 

[jkuhn1113]

Well s#$t...that ain't good...

Yours leaking?

 

[ShadowsPapa]

Think I found the problem... Transfer case seems to be leaking.

Doesn't matter if you have any other problems, noises, rattles, whatever - THAT is not good no matter what.

 

[jkuhn1113]

Doesn't matter if you have any other problems, noises, rattles, whatever - THAT is not good no matter what.

Yeah taking to the dealer first thing in the morning. Hoping it’s not a long fix and also solves my issue.

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