Hi all!
Please not all work done to the car in my ownership has only been done at the Agents.

I'm going to attempt to keep this brief. I've got a 2014 V8s F-Type which had a vibration at the rear lat last year. Turned out to be a loosely mounted diff, this was secured properly by dropping the rear sub frame at my local JLR dealership, which was a huge job.
I then had the vibration come back after about 1 month. Took it to another workshop since I've had SUCH bad service from the agents only to find out that JLR had missed about 5/6 bolts on the mounting of rear sub frame.
I of course went right back to the JLR to complain about this and they replaced All the bolts on the rear subframe (after having to argue that 5/6 bolts don't just fall out in a month, since they wanted to charge me!).
The vibration has been gone since, but since I have felt that the rear end is slightly skittish, upon further investigation I found that the space in the rear arches on either side is slightly different. The rear left wheel is just over 1cm more forward than the right side. I though this may be the reason for my skittish rear end. Anyway about 3 months after that whole above ordeal with the bolts and subframe I needed the supercharger isolator changed. When I took it to JLR to have this done I mentioned this gap and the service agent said she'd inform the workshop. The workshop came back saying that the Rear differential needs to be replaced but the gap is normal. I though this to be absolute rubbish but just haven't had time to revisit this. Now I have that time, so I am seeking knowledge from all you helpful people because I believe it's due to them mounting the rear subframe incorrectly or some such.

I can provide pics.

 

I would be checking the rear tires for abnormal tire wear. After repairs are made I would also have a four wheel alignment done to make sure everything is aligned correctly if that is not done when the repairs are made.

If the dealer insists that the condition is normal take it to a front end alignment shop for a second opinion.

 

If the back end is out of alignment you should find the steering wheel won't be central when driving in a straight line (ask me how I know!) - the car will have a tendency to "crab".

 

Something installed wrong, the only adjustable setting on the rear is toe, which in turn slightly affects camber and thrust.

If your left rear is indeed 1cm off center, something is seriously bent, installed wrong, or even missing.

 

Thanks for the advise all. I'll take the car this week to the suspension shop that identified the missing sub frame bolts and see what they can find!

 

UPDATE: So it turns out that JLR never did any form of wheel alignment on the car after working on the subframe which lead to the rear wheels toe being completely out. This meant that because the one wheel was facing in and the other out it created the difference in gap.
So now I can instantly feel the car sitting firmer on the road and being less skittish while driving. Ridiculous really that JLR gave me back the car like this AND then when I questioned it said that it's within spec.

Anyway though I still have a whine coming from the rear end between 95-105km/h, I think it's from the differential but can't be 100 sure. Would changing the differential oil be a good step forward (I don't think it's ever been done)?

 

Did anyone check the rear tires for abnormal wear?

 

I always request an alignment result print out for Peace of mind and later reference.
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​​​​​​When I changed my rear toe link and springs, my rear toe were out by 0.6 and 1.3 deg, which works out to be 4 to 8 times off of factory spec, it messed with my torque vectoring, the car thinks I was drifting all the time and applied brake whenever I make a slightest twist on the steering wheel, I could hear the tire locking up and squealing, it was fun😂

 

I also always ask to get a printout from the alignment and that goes in my files. "We checked it and it's in spec" isn't good enough. Even if true, the specs can be fairly broad. They cover the "not perfect, but close enough it's not worth adjusting" case.

As for the oil change, there's no reason not to at this point, even without the whine. You could even pull a sample and send off for analysis, but I haven't had that done on a diff. I'm not sure the value there.

 

Well so far they have been nothing short of fantastic. I’m having him but it constrictor grip on it which seems similar to what you are talking about.

so is it their customer service or actually product/end result that has been underwhelming to people ? I’ve stopped listening a lot to people on the internet. Especially when it comes to guys in the gun world. h&K specifically. They are the worst. I’ll report back.