2020 Max Tow M220 rear differential woes

[Caveman]

Interesting to hear a few others have had similar experiences! My 2020 was built 8/19, and it truly is an open differential, not a LSD. Over the phone, the off-road shop guy did say he thought it was likely the pinion bearing. Depending on how far he has to get into things, I am considering an Eaton E-locker if I'm already in for a fairly serious teardown. Thanks for the link to the tapered bearing upgrade kit. I will definitely bring that up with the shop when I take it in later today. Thanks also to the poster who supplied the TruTrac link. I'll have a look at that as well.

I'm sure I did sign a diagnostic at the dealer. What ticks me off is I didn't get a diagnosis beyond the one I walked in with: metal in the rear diff. I would have liked to have been told up front: "if there is metal in your diff, all we are prepared to do is replace the whole unit." Barring that, I would have preferred they'd have saved my (new, but likely contaminated) gear oil to put back in so I could drive the few more miles to the gear shop on a diff they declined to repair without paying $75/quart for their gear oil! In all fairness, they refused to do that up front, but that lack of flexibility on their part ended up costing me. I wouldn't put possibly contaminated gear oil in a repaired diff, but I would have had no issue pouring it back into one that had just been opened and closed up again without any repair.

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[Gvsukids]

If you have a MaxTow, that rear diff is NOT open/unlocked. It's the "Anti-spin" diff aka a clutched LSD (fails open though).

In early 20, it was. I added the optional trak-lok to our build

 

[Dilly’S Willy]

@Caveman You can verify with THIS LINK what features came with your VIN. Just add your VIN to the end of the URL in the link and it will generate your OEM window sticker and all options.

I did hear the '20MY didn't always come with them, but the LSD was standard later at least to help with traction while towing.

Just trying to be helpful. Enjoy your new locker!

 

[VA6489]

Interesting to hear a few others have had similar experiences! My 2020 was built 8/19, and it truly is an open differential, not a LSD. Over the phone, the off-road shop guy did say he thought it was likely the pinion bearing. Depending on how far he has to get into things, I am considering an Eaton E-locker if I'm already in for a fairly serious teardown. Thanks for the link to the tapered bearing upgrade kit. I will definitely bring that up with the shop when I take it in later today. Thanks also to the poster who supplied the TruTrac link. I'll have a look at that as well.

I'm sure I did sign a diagnostic at the dealer. What ticks me off is I didn't get a diagnosis beyond the one I walked in with: metal in the rear diff. I would have liked to have been told up front: "if there is metal in your diff, all we are prepared to do is replace the whole unit." Barring that, I would have preferred they'd have saved my (new, but likely contaminated) gear oil to put back in so I could drive the few more miles to the gear shop on a diff they declined to repair without paying $75/quart for their gear oil! In all fairness, they refused to do that up front, but that lack of flexibility on their part ended up costing me. I wouldn't put possibly contaminated gear oil in a repaired diff, but I would have had no issue pouring it back into one that had just been opened and closed up again without any repair.

Dealership are no longer repair shops. They are remove and replace shops. Most do not know how to set up a gear set they just replace the whole axle assembly and install axle shafts. How do I know, Happened twice to me in two different shops. within 2 weeks. Local dealer could nto find the vibration that turned in the rear axle tamping on my 3500 Dually...until I showed them that the spring design set up a harmopnic that excetes the load leafs and ends up making the axle jump at speed.

Pinion Bearing on these rigs are a double row ball set up ( Horible idea/design but low rolling resistance) replace with tapered bearings. also this will eb an extensive rebuild if the shop is worth it's salt. ring and pinoin, all bearings. A good time to upgrade if you want to a Truetrac or other reputable locker/Limited slip device.
Cheers

 

[Dilly’S Willy]

Dealership are no longer repair shops. They are remove and replace shops. Most do not know how to set up a gear set they just replace the whole axle assembly and install axle shafts. How do I know, Happened twice to me in two different shops. within 2 weeks. Local dealer could nto find the vibration that turned in the rear axle tamping on my 3500 Dually...until I showed them that the spring design set up a harmopnic that excetes the load leafs and ends up making the axle jump at speed.

Pinion Bearing on these rigs are a double row ball set up ( Horible idea/design but low rolling resistance) replace with tapered bearings. also this will eb an extensive rebuild if the shop is worth it's salt. ring and pinoin, all bearings. A good time to upgrade if you want to a Truetrac or other reputable locker/Limited slip device.
Cheers

Whole facts here! I've had similar experiences myself, the customer shouldn't have to teach the mechanic how to do their job.

And you nailed it, Low RR means more mpg and less emissions. Same excuse for these thin ass oils and exploding engines.
- Almost like they planned the failures after removing reliable vehicles from the face of the earth...to "save the earth".

My 21' JT 6 speed gets the same MPG as my '95 grand prix (4 speed auto) with a cracked block, 18-21mpg average. Hmm, my race car gets the same MPG too, but can make 500hp.
- Something doesn't add up.

 

[Gladiator Brad 704]

You knew the answer before you even asked the question. You should have never gone to the dealership. Like the previous post have said, there are a lot of better options for less money. If you don't do the work yourself just check around and find a good 4x4 shop. The dealership hasn't touched my 2020 jt since my last free oil change.

 

[1550jrit]

2021 Mojave with 58.7k miles on the odometer and one month left on my powertrain warranty. My rear pinion bearing just went out and is being covered. (even though I was previously re-geared and the dealership knows about it, which was cool of them). I brought it in at 55k for my normal oil change and mentioned that I had a whirring noise at low speed, but the mechanic said everything was normal sounding during the test drive.

3k miles later and the whir was becoming more pronounced. I was going out of town for a week and scheduled another appointment. The tech was able to isolate the sound and sent me a video of the truck in the air with the drive line engaged at low speed (10-20mph). Sure enough, the exact sound could be reproduced. I’m glad they found it while I was still under warranty.

 

[NC_Overland]

The 2020 rear ends had issues. When mine went out at roughly 16k miles they replaced the entire unit and sent it to Dana to examine and address the failure point. It was bone stock and I hadn’t towed anything with it yet.

 

[Caveman]

Wow, 1550jrit, that is cutting it close!

So there have been some developments. I called the service manager at the dealership I took the GL to, asking for a refund of my "diagnostic fee," given that I hadn't really gotten a diagnosis or any real options. He contacted Stellantis, which agreed to pay 55% of my repair costs even though I am well out of warranty. They were estimating $4500 for replacement of the pinion bearing, so I still would have been out over $2K for the repair, assuming that there were no further complications.

While I do appreciate the gesture, both on the part of the service manager and Stellantis, I declined, as the truck was already at the local offroad shop, with an estimate of $906 to replace the pinion bearing.

When the offroad shop actually went into replace the pinion bearing, it turned out that the problem was a failed carrier. I can't picture quite how it failed, but I've asked them to save the old carrier for me to look at. I elected to replace the failed carrier with an Eaton TruTrac (thanks to previous responder who suggested this!). I also asked them to do the taper bearing upgrade on the pinion bearing. The part had already been ordered, and I would prefer to address this vulnerability while the differential is apart. Bill is estimated at about $2100, but may end up being a bit more if gear lash has to be adjusted.

Recall that my original estimate from the dealer was about $6500 (tax included) to install a new M220. If I end up with my original M220 upgraded with a TruTrac and stronger pinion bearing for a third of this cost, I will be delighted....

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