Rear rotational knock from differential at low speeds.

[AlamedaJeep]

I have a 2018 JLU Sport, non S, w/the 3.6 engine, the tow package, 6 speed manual, and the Dana 44 rear w/the anti spin, and yes, I have the rear noise, be it a knock, click, or clunk.

I get a noticeable click noise from what sounds like the rear end, taking off from a dead stop. The noise either doesn't happen, when you need to show a dealer, to a very loud cluck, which just happened yesterday.

Anyway, I brought it in once to the dealer, and of course, nothing happened. I don't know what the local temperature was at the time. This past Friday I brought it in again, especially w/the local temperature being in the upper 90's, so the gear oil won't possibly muffle anything, and drove w/a mechanic/supervisor, and sure enough, it did happen this time, and he claims to have heard it as well. He immediately made the claim of it being probably a loose powertrain, especially having a manual transmission w/the anti-spin rear. I told him that I've had other Jeeps, including a couple of JKU's, w/similar hardware, and I never had this noise on them. Also too, I've had pickup trucks as well, w/manual transmissions w/a limited slip rear, and again, no issues w/them either.

It could be simply the Rake and Pinion gear wasn't adjusted properly, or the Anti-Spin, or more properly called, a Limited Slip, is failing.

My Jeep is totally stock, w/stock wheels/tires, so there are no excuses there. It's also well maintained. I do go offroad, such as dirt roads and such, but nothing like the Rubicon, or anything crazy like that.

Anyway, I made an appointment to bring it in for them to address it. I'm hoping they open up the rear differential, checking out the oil for any abnormal materials and such, and making sure that they put the right weight oil back in, full synthetic, because of the trailer towing package, as well as the moly additive for the anti-spin differential. Also too, to check, and measure any play in the powertrain as well.

While there, I'm going to start having the powertrain oils changed as well, starting w/the transmission and transfer case. The vehicle now has almost 19K miles on it. I like to change the powertrain oils w/clean oil after vehicle break in, generally around 15K.

Oh, and the mechanic/supervisor said that in the meantime, he'll check out some used Jeeps on the lot, though that may be a problem since they rarely have any Jeeps, new or used, w/manual transmissions.

This has been the only real issue that I've had w/my JLU since I bought it new, though the wheels were a little out of alignment when I first got it, and I immediately had that addressed.

Please report back if you can. I’ve got a similar Jeep with about the same mileage and I’m starting to get the clunk when starting from a stop too.

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[GoHack]

That's what the Anti-Spin Differential is, a Limited-Slip w/a Clutch. It's an option and not a standard item on the JL. The clutches do eventually wear out and required replacement over time, which varies on the type of driving and maintenance done.

1. A standard open differential, w/no Locker or Anti-Spin Differential, will have but one power wheel in the rear, and one in the front, thus you really only have a two wheel drive vehicle when in four wheel drive.

2. The Anti-Spin Differential rear axle (Limited-Slip) option, has an open differential front axle, so you really have a three wheel drive when in four wheel drive (4Hi and 4Lo). With a Limited-Slip differential, in a straight line, the rear wheels are locked together, like a locker, but due to the clutch, allows for the rear axle to make turns on dry pavement w/o the wheels binding. It can be used on dry, rain, and snow covered pavement, as well as on dirt, and it is automatic, in 2Hi, 4Hi, and 4Lo. The front has an open differential, and thus only has but one power wheel.

3. The model w/the Lockers, the Rubicon, are normally open differentials in 2Hi, 4Hi, and 4Lo, and can only be Locked in 4Lo w/switches, allowing the two wheels in the rear, as well as the two in the front, to be locked, individually, or both. The two wheels on each axle are literally locked together, w/no slippage, thus can only be used on dirt and such, or even on snow cover pavement, and can't be used on dry pavement, except maybe in a straight line in an emergency.

For everyday driving, in areas w/little to no rain and snow, together w/very little to no offroading, the models w/the open differentials are just fine. Then again, you don't really need the four wheel drive either.

In areas w/rain, and especially light snow to heavy snow, as well as general offroading, the Limited Slip option is the best compromise.

For heavy offroading only, like the Rubicon Trail, the Lockers. The Jeep Rubicon model, for most people, is an over kill, hardware wise.

I might add, there are aftermarket lockers available for those w/open differentials, for later installations.

These are my views of course, and I'm sure others will have theirs as well.

 

[Toxiclows]

tear your diff cover off a d find the problem. there is an 80 page thread on here about this issue. like others mine. was louder once lifted and 35’s on. tire cover and found crazy metal and black fluid.

 

[GoHack]

Please report back if you can. I’ve got a similar Jeep with about the same mileage and I’m starting to get the clunk when starting from a stop too.

Sorry for being late in responding.

This time they heard the noise. There's was more than one witness.
They brought in a Jeep Rep and they said that it was normal play w/the manual transmission. I've owned plenty of manual transmissions over the years, including in Jeeps, and that's not normal.

Also, hearing it in my Jeep, it sounds more like the rear axle than the transmission. My guess, the Limited Slip, but that's just a guess.

It doesn't seem to be as bad when it comes to colder temperatures, most likely due to the gear oil being thicker, which helps muffle it.

All I can say is, that it is documented now, so we'll see.

 

[2Caddies]

I came across this thread looking up a different kind of issue. I’d like to add a little with my experience with this knock issue. Late in 2020 my 18 JLU Sahara with the Dana 44 was making the clunking sound at low speeds. It was very obvious and easy to hear with the windows down.

Took the Jeep to the local Dealer where I purchased new. I had installed myself a Teraflex ST3 lift with 35” Nitto Ridge Grapplers on some 20x12 RBP rims. Nothing too extreme for the reputation these Jeeps have. Dealer couldn’t replicate said noise. I had to take the tech for a ride to duplicate the noise which was very obvious to him. They never questioned the lift or tires. I was at 35,500 on the odometer so warranty is going to cover the issue.

The dealers first diagnosis was bad axle bearing. They then tried to charge me $149 for rear dif maintenance. Meaning changing out the rear dif fluid and a cleaning. They told me the dif fluid was black and smelled burnt. They told me that my larger tires requires dif maintenance faster than the factory maintenance schedule and that’s what caused the burnt dif fluid. I’m fairly mechanically inclined and have been working on cars since I was a kid. I questioned the charge because I knew the fluid had to be drained to pull the axle and if the bearing went bad it would need to be flushed clean. The dealership told me that they reinstall the old fluid. I politely disagreed with that.

After one week they called and told me the axle bearing was replaced along with the dif fluid. The shop advisor then reported to me that now the clunk was even louder. I should come get the Jeep and then bring it back three days later.

They then determined that the rear dif was the problem and I’m not sure if they were supposed to say this to me but the lash was shimmed too loose from the factory and cause premature wear on the entire rear end. So now I’m really fighting the dif maintenance charge still pending. I believe all these Jeeps that are experiencing this clunk will have the same issue. Two months after I brought the Jeep to the dealer the rear end was rebuilt. Waited on parts for over a month. Which also leads me to believe that FCA is aware of the problem or a lot of others are getting this repair performed.

After 800mi. of driving I didn’t get the repeat clunk that was there before. However after a trip up North a month ago at speeds over 70mph I have a vibration I feel in the seat. And when I decel from 78mph it sounds and vibrates like a Jake Brake on a big rig.

Returned to the dealer and they again couldn’t duplicate the sound and once again I had to duplicate it for them. They tried blaming it on tire noise. Again I politely disagreed. I then took the warranty manager or some title like that for a ride and she did agree there is an issue and it’s not coming from the tires. I’ve driven this Jeep up North every weekend for years and the tires only had 12,000 miles on them and had been rotated 3 times already. Never had this vibration or any vibration before.

It’s been over 3 weeks and they still can’t figure out the issue. They apparently went through the front dif and next is the transfer case. I believe it’s the rear dif that was just repaired. It’s the only thing that was changed since the last time I drove it up North. They did tell me that it will be covered under warranty even though I was past the warranty period. I was at 36,300. They would have no matter what or we would have had a big issue. They also gave me loaners to drive each time but I’ve not had my 3yr old jeep to drive for over 3 months total in two different issues. And the time is still counting.

Sorry about the long rant but thought maybe my experience will help out some others.

 

[SAF]

Jumping on this bandwagon and saying I have the exact same noise in the previously posted videos in this thread. I bought a new 2022 JL Rubicon and didn't notice this noise during the test drive, only after about 200 miles when I was pulling in my driveway with no A/C or radio on.

Obviously those two things being off allowed me to actually hear the rear end noise.

I found this thread and others like it, and after my own research I took it back to the dealer. I had one service rep ride with me, and after he clearly heard it, he sent me over to a larger service building. I made an appointment at said building, and then had the foreman ride with me.

He definitely heard the sound in question, and told me he has never heard anything like that before. He told me to break the jeep in more and come back after another 300-500 miles if the noise persists.

I really enjoy this jeep and I wanted to chime in to say that this is still an issue. I will probably just go to aftermarket axles at this point because I don't want to get caught up with having my vehicle sitting at a service center while supply chain issues continue to plague the world, and even if it does arrive in a timely fashion, I don't want to run into the same issue all over again.

So, new axles for me, or I might try to trade this jeep in for a model without any noise (especially now that I know what to listen for).

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