Grinding/vibration/rumble Noise at ~30mph

Where would you describe the vibration as coming from? There is a TSB that could be related to your concern.

TSB 22-001-14 REV. A

SUBJECT:
Steering Wheel Vibration Diagnostic Procedure

OVERVIEW:
This bulletin involves road testing, tire balance measuring, road force variation and flat spotting removal.

DISCUSSION:
NOTE: The respective tire manufacturer is responsible for any “tire defects”.

VISUAL INSPECTION:
Visual inspection of the vehicle is recommended prior to road testing or performing any other procedure. Raise and support the vehicle. Refer to the detailed service procedures available in DealerCONNECT> TechCONNECT under: Service Info> 04 - Vehicle Quick Reference/Hoisting - Standard Procedure. Inspect for the following:
• Verify correct (OEM) wheel and tire, as well as presence of wheel weights.
• Inspect tires and wheels for damage, mud packing and unusual wear; correct as necessary.
• Check and adjust tire air pressure to the pressure listed on the label attached to the driver's door opening.

Our Renegade Trailhawk does something that sounds like what Tony is describing. I'm an automotive engineer with chassis development experience, and the sound/rumbling does not feel right to me. But I get the sense that what I've got is driveline-related. I'm not ready to point the finger of blame at the transmission.

And I drove a different Renegade Trailhawk some weeks ago and never once experienced this. We put over 20,000 miles on a Cherokee Limited 4x4 with the same 9-speed and had no such problems.

It is most noticeable when coasting gradually through 30 mph or applying light throttle to maintain that speed. It is a low frequency rumble noise that you can also feel, at times. To my ear, the sound seems to be coming from behind the driver's seat. If I had to guess I'd say a prop shaft imbalance or something about the rear differential. I'm very confident it's not coming from up front, and it isn't the TSB issue described above; there is zero steering wheel vibration or flutter.

We had the wheel balance checked on a road-force machine anyway. I noticed that the rear wheels had a surprising amount of balance weights on them, so I wondered if there was something to be gained by doubling checking. I had no expectation this was the real cause because the rumbling sound is more substantial than a tire issue, especially since these tires are new and what little wear they do have is very even. Still, try the easy stuff first, right? But the road-force balance checked out. They were fine. My local tire shop didn't even charge me.

Now its at the dealer and they're saying they can't duplicate it. That's not wholly surprising because it is intermittent, I cannot reproduce it at will myself. I have not yet tried manually selecting gears to see if I can force the issue that way. But even if that does work, if a particular gear is associated with the noise, I'm still betting it's a driveline resonance and not a transmission issue.

Same issue here, though I would characterize it as a rumble rather than a grinding. Its something you'd think you'd feel, but there's no vibration or shake. Sounds like it is coming from the tail end of the prop shaft or rear diff. It is almost as if the rear axle disconnect isn't fully disconnecting. And this is all auto mode, tranny set to drive, about 30 mph coasting or very light throttle on smooth asphalt driving straight. Doesn't happen all the time, but often enough.

It never seemed like a tire issue, but we checked the balance anyway with a road-force balancing machine. No problem there.

Thing is, I drove a different Renegade Trailhawk (an early press car) extensively and never heard/felt a peep. Interesting to hear others have observed a reduction or elimination of the noise in 4WD Lock. Makes sense to me. Don't know why I didn't try it myself. Confirms my suspicions as to the possible source. I'll try it. If it works, it'd be easier to get the dealer tech set on the right path.

Going Commando said:

I experience what I would consider some low frequency gear grumbling or whining (to be more specific) when slowing down sometimes. When I flip the shifter to manual mode, the transmission is either in 5th or 3rd when the noise/feeling is occurring. While I don't suspect anything is wrong, it's was definitely concerning to hear/feel the first. I'm used to it now though.

Click to expand...

I am experiencing this also while slowing down, there is no way it is normal. I already took my Jeep back for harsh shifting while taking off in the lower gears, they did a software update and while it's a little better, the problem is still there. Now I have been getting this moaning/vibration while slowing down from around 30mph until fully stopped. I emailed my Service Director to bring this to her attention (I use email so I can have written documentation of my concerns) And they are basically avoiding the issue and blaming it on other things.
Here is her quote:

This vehicle has a very different feeling transmission then anything I am sure you are used to . These 9 speeds do shift harshly at times depending on what the computer is seeing. They also have what they call adaptive shift – this means that the computer learns your driving habits. This process will take 1000 + miles of driving. (this would be from the mileage of when we performed the software update.)

Something to watch for when you are feeling the vibration is the ac compressor running?

Seriously? Is the A/C running?? I know the difference between the A/C bogging down and a groan/vibration!

She ends the conversation with:

We have not had any transmission issues as of yet on your type of vehicle, other than just software updates to change shift strategy’s

There have been no issues as of yet with this transmission??! I wonder if FCA is contacting dealers and dictating to them what to tell customers when they have transmission issues? Shifting harshly at times is considered normal? I don't think so.