Hi all, new to the forum, and just curious what others think about this. Two years ago I traded in my 2007 Shelby GT500 for a 2015 F-Type V6S. It was three years old, still under warranty and 10k miles. Amazing car, and love it more than any other I've owned. No problems whatsoever. About a year and 12k miles in I hear what I would describe as a knocking sound. At first I thought it's something in the trunk rolling around, it almost sounds like a bottle of soda. Then I thought maybe the rear battery was loose, or the tow hook. I took everything apart, still nothing. At one point I even thought it was the subwoofer misfiring behind the seat, as it almost sounds like that sound too. Did not think it was the rear differential. Fast forward, brought it into Jaguar, they said they thought it was something loose in the trunk too, but then they said they drained the diff and it was that. Weird to me, as I'm not a mechanic, but I've had diff problems on my Shelby and it was a "whirring" sound that seems common and constant. This happens randomly, but especially so when making slow turns.

They replace the diff. Two months later and I start hearing the noise again, light at first and then louder over a couple weeks just like the first time. I can't imagine it's the same thing. Bring it back in. They said the oil looked ok in the diff, but they think it's that again, replace the diff again. In the back of my mind, I remember being stuck in the snow, slipping and sliding first 45 minutes to get out of a hotel driveway, and then driving 25mph along country roads barely holding on to the road. And I think maybe perhaps that burnt out the diff? Didn't seem likely but couldn't think of anything else. The car is never raced or tracked. Maybe some spirited driving, but nothing I would call extreme or any different than any other car I've owned. Less than a few thousand miles on the new diff.

They replace the diff again. Noise goes away again. Two months later, I start hearing the exact same weird noise again, same exact pattern. Bring it in again. They have to go to corporate this time because they can't figure out why it keeps breaking. They really didn't seem sure it was the rear differential, but they said since the noise went away each time they have to assume it's that. They just call me now and say they are replacing it again. I ask them if I need to do something particularly special, like a super soft break in period, or change the fluid after 1000 miles or anything. I do not want to have to keep going back for this, and like I said, I really don't think I'm very hard on the car, occasionally WOT merging onto highways, but for the most part it's a way to get to the store or park or whatever.

I'm at a loss, and not a professional mechanic or anything. I'm wondering if others have advice. I've tried to think of any other explanation like is there something else wrong in the drivetrain that's driving the diff the wrong way causing it to break? Is it maybe not that, and something else? It's weird that the noise does indeed go away each time, but it's the exact same issue now on three differentials with the exact same weird noise? No other issues with the car, and aside from the noise, no driveability issues either. Jaguar doesn't seem very confident to me, and seems kind of confused on this. They even asked about me replacing tires in my carfax (I suspect they thought I was tracking the car and burning the hell out of the rear diff or something), but it was due to screws/flats in the tire.

Any and all ideas/thoughts appreciated!!

 

Well....That sounds pretty crazy, so any suggestions will likely be the same. The big issue in any theory, is that we ARE assuming the differentials ARE actually bad (or were 3 times?). If that is in fact the case, logic would say, something is destroying them. Do you have RWD or AWD? Not sure what was available for 2016 F- Type V6 - I think either were. At any rate...You have a driveshaft going in to differential and axles coming out...so if something is tearing up the differential gears, it is one of those, or some combination of them. While extremely unlikely, if you had tires / wheels, that have an extreme difference in circumference (or diameter), one wheel is trying to turn faster than another and could damage the diff. (I would think JLR would have checked that first)?

Other possible causes might be bad/bent driveshaft or axle(s).

These are just extreme possibilities, as Jag is actually looking at your car, and I am just responding to your description. There is no magic in cars...either something going into or out of the diff is creating issues with it, or it IS NOT the diff at all. It could be something they are doing when they change the differential that temporarily removes/reduces the noise, and then it comes back

Sounds like a tough one.

Good luck,
DC

 

Is there any chance that your car was in a bad wreck and was repaired by pulling frame? If you have out of alignment transmission and differential, it puts extra stress on both.

 

I would suggest the suspension geo is way out of whack putting undue loads on the diffs...kinda what SinF is suggesting.

 

Is the sound you are hearing (analogous to something rolling in the trunk) manifesting during acceleration/deceleration, when turning, or both?

 

it’s always been worst slow turning with almost no gas. Barely ever hear elsewise. The sound does not sound like a whir or a grind. It literally sounds like banging into the walls in the trunk or like a subwoofer/deep base speaker popping and backfiring. It will pop off a few And then stop.

 

I don’t think so, but of course can’t be 100% sure. I asked Jag and they said they checked the drivetrain/driveshaft and were required by corporate to check all possibilities for why the rear diff continues to fail.

 

Thank you for all the ideas. Just got it back with the third new differential. They are clueless. They said they checked everything and were required to as corporate wanted answers etc including checking the driveshaft, tires and wheels. There was a slight bend in the front wheel from potholes but doubt that could be it. They also said they see a slight leak in one of the rear struts and probably needs to be replaced soon, but doesn’t seem they think that is the cause either and they didn’t pick that up on the last two differential replacements.

Still at a loss. They gave me a number to call to speak to manufacturer. Spoke to tech and he said no way it should be failing after two months two times, not to mention the first time after 4 years and about 22k miles. Feels like I’m waiting for two months for it to fail again and Jag deny the one year warranty on the part and claim I’m burning it out or something.