Rumble/vibration after pinion seal change, help!!

[SOLVED] see my latest post for solution

Hey guys I could use some help. I apologize for the longish post.
-------Background info-------
I have a 2018 JKU Rubicon. Slight mods, I have 35" tires and the Old Man Emu 2" heavy lift kit (there's others but those are the relevant mods). After the larger tires and lift I felt like the power was a little lacking, esp on the freeway. Upgraded my gears. I got 4.88 yukons front and back... I debated the 4.56 but figured the 4.88 would give me room to grow. Gears were great. Did a nice 1000 mile break in period with plenty of warm up and cool downs. At the end of that took it back to the guys that installed it. They pulled off the diff covers inspected the gears for wear and said it was good to go.... about 800 miles later...

-----Current problem--------
So I had a leak in my radiator, and had it scheduled to go to the dealer to be replaced. Prior to bringing it in I noticed a decent size front passenger side axle leak also oil on the back of the front diff. While at the dealer they came back and said it had a R front axle leak, and pinion seal leak and a drivers side rear axle leak (which would be covered under warranty) I told them that I had recently re-geared it (which meant it wasn't under warranty)... I thought about taking it back to the guys that installed it but the problem is I supplied the parts got the gears during a sale on northridge 4x4. So if there was an issue with the parts basically none of it would be covered. On top of that if their instillation damaged something I wasn't sure if I'd want to pay them to tear it apart again. So I had the dealer do the repair... so 3 seals, 1 radiator and $2000 later I got my jeep back.

The next day while heading into work getting up to 50mph I started to feel a vibration, the faster I got the worse it was by the time i was at 60-65 it was audible and felt like the whole front end of the vehicle was vibrating.. i say more of a vibration and not shake. And it was audible like a loud rumble, at least to me. Usually in the jeep on the highway wind noise is the loudest but this is way louder. I took it back to them and initially they thought it was tires out of balance (i forgot to mention they rotated the tires). Tires were out of balance, they re-balanced them and test drove it and said they thought they still felt something but it was less than before. So they put all the tires back to the way it was initially and tested it and I was told it was fine, they didn't hear anything and they wanted me to drive it for 500 miles then look at rotating them again to see if it comes back.

I got my jeep and took it on the freeway... still there. So I got the rep to drive in it with me and pointed out exactly what I was noticing (a very loud, very obvious vibration starting around 55-60mph and increasing with speed). So they pulled the front drive shaft off and test drove it and he called back and said it runs perfect just like I had told him... No more noise or vibration, slight tire noise, slightly more wind noise and nothing else, pretty quite really. So he tries to tell me it's the drive shaft that's bad and It must have been caused by the barely 2" OME lift... But from my perspective I gave them a great running jeep, and picked up a massively vibrating jeep after they changed 3 seals. There's no way in my mind that the drive shaft went bad without going anywhere... Could it have been over extended while on the lift? Is it possible it was installed wrong? Is it more likely that they didn't put stuff back correct when installing the new pinion seal (I think you have to take off the nut for that)? Maybe didn't torc stuff completely? Maybe dropped the drive shaft?


----------Less important after details-----------
They wanted me to purchase a new driveshaft, one from quadratec that was meant for lifted jeeps, parts and labor around $900. I asked shouldn't it be under warranty because I have less than 60,000 miles. He tried to say that wouldn't be covered because of the lift and I told him that a 2" lift doesn't void the axle and they'd have to prove that was the cost of the problem. secondly it was completely fine before they worked on it. On top of that On dash cam I have them test driving it and calling me crazy and the jeep drove fine. This was before I drove it with them and pointed out the clear problem. It shocks me that they couldn't identify what they claim is a bad drive shaft. The bigger problem he said was that mopar front drive shafts are on national backorder (from covid) for the dealership and he has no idea when they can get one. I'm worried I could replace the drive shaft and have it vibrating just as back only to find out that they didn't put thing back together right and now I have a damaged pinion bearing and damaged ring and pinion.

Thoughts? What are the things it could be? Possible causes? Ideas on how to identify or how to proceed?

-Ben

 

[SOLVED]

So this has been resolved. It's been a while but I just haven't updated it. So recap, Dealer was saying the front Drive shaft was the problem... vary unlikely because I had driven for several thousand miles after lift with no issues and the vibration appeared instantly after dealer touched it. That said with testing they were correct that the problem completely disappeared after front driveshaft was removed. TORC motorsport tested the preload and said it was good to go. They gave me a loaner driveshaft, to test until the dealer got the backordered warrantied part in. The vibration was still present with the second driveshaft so I had no confidence that the new one from mopar would make any difference. I mentioned this to the Dealer that still said they were not going to look any further into it until they had the warrantied new drive shaft. So a little over a month of waiting and the part came in, and magically it made no change in the front end vibration. I asked the dealer to please look over their previous work. They gave the vehicle to a different mechanic at the shop who noticed some oil leaking at the plug welds.... they suggested that I had poor plug welds which may have led to the center carrier rotating during 4wd causing the pinion angle to be off leading to the front end vibration.... This is amazing since I had zero vibration for the 1000 miles prior to dropping it off at the stealer dealership and immediate front end vibration after.... Also despite being under powertrain warrenty they suggested that they would not be able to warrenty this since I had changed out the gears. 4.10 - 4.88. I told them that regardless of gears if the issue was caused by poor welds that's a warranty-able problem.

At this point having no confidence in the direction the dealer was taking things I decided to pay out of pocket the guys at TORC to figure it out. Initially they felt it could be a front/rear DS problem so we did try front and rear aftermarket DS which did significantly improve the situation. We tried adjustable control arms which actually seemed to make things worse. Going back to what the dealer touched, they tested the pinion with a dial indicator and there it was. My Pinion shaft was bent...

So somehow when the dealer was changing out the pinion seal the bent the pinion shaft. Probably they removed it with a mallet and not a puller. So as a result I had to get a new set of 4.88 gears for the front end and magically the problem was 100% resolved. So the lesson I learned is don't have the dealer do any critical work. If they mess something up they won't own it and will do everything to make it more expensive than needed.