Rear axle howl?

[Grayone]

New Rubicon, manual, 4:88 gears, 35,s 3.6 Liter. When I lift off gas and rear axle not underload it howls. Pushing in clutch has no effect. Differential warm to touch after driving. Only 75 miles on Jeep. Dealer time? Or as HD would say, "they all do that..." Thoughts?

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[azwjowner]

At which speeds does this occur?

 

[Grayone]

Highway speed is most notable 55-70.

 

[azwjowner]

Highway speed is most notable 55-70.

That sounds like mine. Since new, my manual Sport has had a whine on coasting above 55 MPH. It disappears below that speed, and is most noticeable when coasting down from 70.

Most people will tell you it's a gear issue, pinion depth, pinion preload, etc. I initially ignored mine for 5000 miles because I planned to regear anyway. When I regeared, the sound persisted exactly as before. The odds that both Dana and me messed up the pinion preload or depth in the exact same way are very slim. So my thinking is it's either my axle housing somehow or it's a different component causing the noise.

If it doesn't bother you, and your power train warranty is still in effect, you might take a wait and see approach.

 

[Grayone]

Think I may do just that. Irritating however! Thanks for the reply.

 

[WontonJLUR]

Are they factory 4.88s or did you have them done post purchase? Sorry for the potentially ignorant question, my JL is a 19 and I have no idea what gears are offered from the factory these days.

if factory gears, you could take it up with the dealer. At least start the “complaint” paper trail early.

if aftermarket install, there’s a chance it wasn’t done precisely enough to ensure quiet operation. There’s a good bit that goes into a re-gear operation.

likely won’t solve much, but the easiest thing you could try at home is to drive around for another 300-400 miles and change the original gear oil. Not a bad practice to do on a new vehicle either way, and not expensive at all.

 

[Bulletbill]

Mine is quiet. I would go to the dealer. Might not be the axel, could be a wheel bearing. I always go with better safe than sorry, but I am safety officer in the military so I usually measure risk vs reward. In this case, new jeep under warranty makes it a no brainer.

 

[JLeco2022]

i noticed if i turn up the radio all the money sounds ago away

 

[Grayone]

Factory 4:88's. Yeah, thought about wheel bearing but the heat in the pumpkin makes me think differential. Who knows with Jeep quality control the factory might have forgot to add gear lube. Calling dealer on Monday. And I don't listen to the radio much.

 

[azwjowner]

Factory 4:88's. Yeah, thought about wheel bearing but the heat in the pumpkin makes me think differential. Who knows with Jeep quality control the factory might have forgot to add gear lube. Calling dealer on Monday. And I don't listen to the radio much.

The rear axle gear oil runs about 230 degrees F @ 75 MPH, so a warm pumpkin is perfectly normal.

 

[Grayone]

I realize that, but felt the heat was excessive from past experiences. Thanks for the replies.

 

[Grayone]

Update. Dealer pulled diff cover. Non normal gear pattern. Waiting for shim kit to correct. Sigh...

 

[Tncdrew]

It'll be corrected, all will be good. Not to worry.

 

[rohdawg]

Update. Dealer pulled diff cover. Non normal gear pattern. Waiting for shim kit to correct. Sigh...

At least you know what it is now. Some scenarios involving the rear diff/gears are pure nightmare fuel.
Hope they get it straightened out for you quickly.

 

[azwjowner]

Update. Dealer pulled diff cover. Non normal gear pattern. Waiting for shim kit to correct. Sigh...

Well, I'm glad you didn't listen to me! (Makes me wonder what my noise is though -- because I have a solid gear pattern now).

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