Whine coming from underneath or front of JT

[T - Rex]

Hi guys! I have a 2021 JT with 1500 miles. I am noticing a whine coming from either the front end or underneath the Jeep when I’m going at slow speed‘s, not sure if it’s there at higher speeds but definitely can hear it at low speeds. When I put it in full-time auto or part time it goes away it is only making the noise in 2 Wheel Dr. Any thoughts?

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[Moe_Fugga]

Can you take a video for sound? First thing that comes to mind is transmission or front axle gears. Make sure she isn’t in 4wd.

 

[T - Rex]

I will try and make a video tomorrow and post it.

 

[JeepCares]

Hi guys! I have a 2021 JT with 1500 miles. I am noticing a whine coming from either the front end or underneath the Jeep when I’m going at slow speed‘s, not sure if it’s there at higher speeds but definitely can hear it at low speeds. When I put it in full-time auto or part time it goes away it is only making the noise in 2 Wheel Dr. Any thoughts?

Is this concern still present, T - Rex? If so, please send our team a private message with more details.

Kate
Jeep Cares

 

[ShadowsPapa]

Impossible to tell without knowing how LOUD it is. A certain amount of "gear noise" can be normal from 4x4 vehicles, even some 2wd vehicle has a gear noise in certain conditions. (reverse for my SX4 is LOUD but I know it's normal as I rebuilt it a while back and the inside of that transmission is like new)
If it's coming from the front end - then it could well be the front differential - and it could be the carrier gears/spider gears up there as they are spinning when in 2wheel drive mode.
Putting the transfer case in either 4 wheel auto or 4H part time locks the front axle disconnect so the carrier gears or side gears are moving with the carrier and not spinning inside the carrier.
So if you think it MAY be coming from the front, my guess is front differential.
Your talking of it being different in 4 wheel drive, either mode, tells me what's different.
Both auto and part time lock the FAD (lock the right axle halves together)
Otherwise the right axle is disconnected so the axles, thus the carrier gears, spin in the differential.

It's very important you did what you did here if you take it to a dealer to describe the noise - that will help them greatly in diagnosing.
They should also instantly know the differences in modes - and what's spinning but spinning ONLY in 2 wheel drive mode.

 

[T - Rex]

Is this concern still present, T - Rex? If so, please send our team a private message with more details.

Kate
Jeep Cares

Is this concern still present, T - Rex? If so, please send our team a private message with more details.

Kate
Jeep Cares

Yes the noise is still there. I took it to my local Jeep dealer and they think it might be a front passenger rotor and pad noise since it goes away when you put it in 4 wheel drive. The though is 4 wheel drive turns off the ABS and relaxes the pad providing slightly more tolerance between the pad and rotor. We just cant seem to prove it. Just want to ensure it is nothing more serious.

 

[ShadowsPapa]

Yes the noise is still there. I took it to my local Jeep dealer and they think it might be a front passenger rotor and pad noise since it goes away when you put it in 4 wheel drive. The though is 4 wheel drive turns off the ABS and relaxes the pad providing slightly more tolerance between the pad and rotor. We just cant seem to prove it. Just want to ensure it is nothing more serious.

Unless there's something different about these that I'm not aware of - you won't get a "whine" from a brake rotor. I've never heard of ABS "relaxing" the pad.
The truth is that because of a tiny bit of rotor imperfection and less than perfect rotation the pad isn't in direct contact with the rotor anyway. It's why with many vehicles you can detect a very very slight difference first pedal push when braking compared to quick subsequent brake applications. I notice that with everything I've owned in recent years - first application the pedal goes down a tiny, but perceptible by me, bit more than the very next pedal application. It's taking up that tiny space.
I also find it odd that 4 part time mode would actually disable ABS - that means if you have it in 4 full time on a dry road that could be perhaps just rain slick - you have no ABS? Really?
That means that my Chevy in auto mode had no ABS the whole time I drove it? It was most of the time I owned it in auto mode.

I also am not sure I agree with their definition of "whine" compared to a slight squeal or squeak or rubbing sound.

I found this quote on the internet - is it accurate? I suspect it is -
>>ABS works really well with full time 4WD, AWD and automatic AWD. However, it works only as long as the center differential of a full time 4WD is not locked.<<

 

[Renegade]

Unless there's something different about these that I'm not aware of - you won't get a "whine" from a brake rotor. I've never heard of ABS "relaxing" the pad.
The truth is that because of a tiny bit of rotor imperfection and less than perfect rotation the pad isn't in direct contact with the rotor anyway. It's why with many vehicles you can detect a very very slight difference first pedal push when braking compared to quick subsequent brake applications. I notice that with everything I've owned in recent years - first application the pedal goes down a tiny, but perceptible by me, bit more than the very next pedal application. It's taking up that tiny space.
I also find it odd that 4 part time mode would actually disable ABS - that means if you have it in 4 full time on a dry road that could be perhaps just rain slick - you have no ABS? Really?
That means that my Chevy in auto mode had no ABS the whole time I drove it? It was most of the time I owned it in auto mode.

I also am not sure I agree with their definition of "whine" compared to a slight squeal or squeak or rubbing sound.

I found this quote on the internet - is it accurate? I suspect it is -
>>ABS works really well with full time 4WD, AWD and automatic AWD. However, it works only as long as the center differential of a full time 4WD is not locked.<<

I agree. Sounds like service department made some crap up because they couldn’t figure the problem out...

 

[ShadowsPapa]

I found more and I was on target - another quote mentions Jeep's automatic 4wd mode -
They say that if in 4L and 4H PART TIME, ABS is disabled, but in automatic mode it is not.

This is referring to AUTO mode - NOT PART TIE 4H -
>>Both ABS and ESC work perfectly. In high range that is. Once you shift into low range the systems turns into a part time 4WD. In this setting ABS and ESC are out of force. And no warning is flashing to remind you of that fact.
It is possible that Jeep assumes that you know what you are doing. <<

I love that last sentence.
Anyway - ABS is enabled in FULL TIME/AUTO mode 4H.
The idea is that in part time, ABS and ESC work in tandem with the auto mode but when in PART TIME mode the ABS gets confused because things are locked and all turning that the same exact speed. ABS handles proportioning, etc. and with the front and rear wheels locked together in part time mode, that proportioning goes out the window.

My bet -the dealership isn't getting it.

I put my beer money on FAD or the carrier gears turning and creating a whine.
Brakes don't whine. You might get a squeak at best, a bit of a grinding sound if the rotors got rust on them.

 

[T - Rex]

I agree, it is not a squeal or a grind. I never noticed anything with my JL with the same motor and trans, only difference being at least as the front end goes is the full time 4 wheel drive and cv axles up front.

 

[JeepCares]

Yes the noise is still there. I took it to my local Jeep dealer and they think it might be a front passenger rotor and pad noise since it goes away when you put it in 4 wheel drive. The though is 4 wheel drive turns off the ABS and relaxes the pad providing slightly more tolerance between the pad and rotor. We just cant seem to prove it. Just want to ensure it is nothing more serious.

I appreciate the additional details, T - Rex. If you will be continuing to work with the dealer toward a repair and need assistance, send us a message.

Kate
Jeep Cares

 

[T - Rex]

How can I reach you?

 

[Poison2569]

Is this concern still present, T - Rex? If so, please send our team a private message with more details.

Kate
Jeep Cares

Did you find out what this was. Mine started doing the same thing about a week ago. I have 1300 miles.

 

[T - Rex]

Did you find out what this was. Mine started doing the same thing about a week ago. I have 1300 miles.

Not yet, i’m taking it back in today, mechanic I typically like to use was not available last time I took it out so hopefully I’ll get some answers today, I will let you guys know.

 

[T - Rex]

Where does yours appear to be coming from and can you describe the sound?

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