As the clunk is predictable, I'm wondering what happens at 7-10 mph in the diff? Locks/unlocks? Is there a module that activates the diff that might be acting up? Something happening in the tranny like a hard 1st to 2nd shift?
I have had the dealerships (we have a new dealership in STL, Imperial just opened in the valley) do all the work so it is documented. Soon as I'm out of warranty I'll have my independent take care of it.
Transfer case fluid change is a scheduled item, did you get that done?
I had my diff fluid changed at 50k, not a scheduled item but I wanted them to document it's condition. They discovered a leaking pinion seal so I got new fluid for free.

 

Just a thought on the low speed start up clunk, check your wheels to make sure they’re torqued to 92 lbs. simple easy to do and check off another box for noise. I agree since you brought to JLR attention the problem under warranty, that should work. Before my basic warranty ended, I brought my car in for any issues that I felt required attention to document the issue before warranty ended. I have a CPO with extended warranty ending in January 23 and I will continue to bring to JLR any issues that I have and hopefully I will not need too. I had the differential replaced this past July and in October they replaced a leaking filler plug, fixed the leak. Good luck with your issues, if’s it a Jaguar dealer problem start a claim with JLR corporate.
Frank my16 s with 44k mikes

 

I know this is an old forum, but I thought I'd add my experience in case it helps anyone. I have a 2015 R (RWD) and have what I believe is the same thump. I had the Differential replaced about 2 months ago with a used diff from a 2017 SVR after the pinion seal failed and gear whine increased (Shop initially tried just replacing pinion seal, but apparently there had been enough lashing that the damage had been done.) With the replacement diff installed and fresh fluid put in, the car seemed to be fine. A few weeks later, this thump started, as described, typically right on throttle or as soon as letting off throttle, typically at low speeds around 10MPH.

The mechanic said that it is the differential bushings that need to be replaced. The diff out of the 2017 only had about 30k miles on it, and the car itself has 48k. Pretty crazy to think the diff bushings would have failed already, but I think I saw at least one other thread on this site that suggested their bushings had gone bad around 20k.

So, its possible that the diff bushings are what's causing it, and that would make sense to me. The shop confirmed its the diff by putting the car on the lift and watching the diff flex far more than it should. @Therock88 you're the resident expert , any insight? Do you think its at all possible that the heat generated by these diffs could expedite bushing failures? I've seen members on some other threads discuss diff coolers (especially if you track them at all, which I do), and I wonder if being in an SVR increased the likelihood that it saw more strenuous (track/"severe") conditions. I'm going to go ahead and have the shop order the bushings and replace them - hopefully that ends the issue for me.

 

And here’s another possible ‘clunk’, from backlash in the drivetrain. Also doesn’t sound like OP’s issue.
https://www.dropbox.com/s/lec9xkk5vo...402V3.pdf?dl=0

 

Interesting. I have that exact same issue. I'm planning on changing the transmission fluid, front and rear diff fluids, and transaxle fluid next week and will definitely check out the rear diff bushings on my car. If that's the source of the drivetrain "clunk" I'll be extremely happy since it looks like a cheap and easy fix.

 

I use Redline 75W90 #57904. Not hard to find in the US and I have been a Redline fan for many years.
Here is my E-Diff fluid change thread on my XJR. Not an F-Type but no I did not have to remove anything but the drain and fill plugs. A lift is a great asset for doing this too.

Note there is some valuable info in that thread! Both plugs for some reason have different heads? Next the fluid level is set by volume and NOT until the fluid runs out of the fill plug like just about every other rear diff!
XJR Rear E-Diff Fluid Change

I have driven the car in excess of 180mph and now over 13K miles with zero issues. In fact I need to change it again!
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So my experience is that this isn't a cheap or easy fix, lol. Well, I suppose if you're doing all the labor yourself, it might be cheap. The shop that looked at my FTR said that its near impossible to see much of the bushing themselves. They really confirmed it by watching the way the diff could flex while under load, beyond what it should. They had someone in the car on lift put it in and out of gear while someone was inspecting from below. Labor to get the diff out is expensive/time consuming as I believe the rear subframe and some of the exhaust has to come off. I was quoted about $800 assuming all of that has to happen. They are going to try to see if they can lower the diff without having to remove everything, but the diff bolts in from the top, not from the bottom, which seems like a really dumb design

 

I also recall a discussion of a need for shimming the driveshaft, though when that needed to be done, and what the symptom was that necessitated it, I couldn't say. But related to the differential.

 

Well, that's disappointing. I assumed it was an easy job after looking at the parts diagram for the rear diff. Please let me know what you find out.

 

I have a similar issue with my rear making a clunk at low speeds, and it was just replaced with a new one something like 10k miles ago. I don't think its the bearings in that case.

 

Possible worn transmission mounts?

 

Or motor mounts. We have had some reported incidents.

 

Coming to this subject a little late, but I'm scheduled to have the differential oil changed next week by a reputable independent Jaguar service place, as preventative maintenance on my recently purchased 2016 Base F-Type 56k miles (no LSD). Is there a different differential oil spec between the LSD and non-LSD diffs? Thanks in advance.

 

You need BOT-720 for the LSD and E-Diff, but BOT-750B in the standard diff.

 

Many thanks scm!

 

As a follow-up, I had both the automatic transmission fluid and differential oil changed last week (2016 w/ 56k miles) by an independent Jaguar service place. Total cost was $950. For my Base model (open diff) they used LiquiMoly 75W-90 GL-5. For the transmission, they used LiquiMoly 1800 Automatic Transmission Fluid. This was preventative maintenance, but noticed the drivetrain seemed a little bit smoother afterwards.

 

omg I'm in the same boat, exactly the same! pinion seal failed and soon diff failed too and had to replace diff, I got a used diff 21k miles on it. hearing a loud clunk on low speed stop and go after replacement. Did you figure out what the issue is?

 

Yes! I did. My b, I should have posted the update. It was the diff bushings. Its crazy to think that bushings with so few miles on them would need replacement, and it requires removing the diff (again, ugh) but that's what fixed this issue for me. At the time, I don't think there were any aftermarket options for something like poly bushings that won't wear out - I assume that's still the case since these are so low volume, but probably worth a check just to be sure.

Also, for what its worth, the used replacement that got installed still has a bit of gear whine Hopefully yours doesn't! After all this I wish I would have just replaced the diff with a new/remanned unit (and apparently with new bushings). I think at this point that's what I'd recommend folks do who are in the same boat unless you have the work done by a shop that specializes in diffs that can get the gear lash perfect so you don't have whine after the pinion seal is replaced.

Also, another reason for that recommendation is that I'm starting to have problems with the diff disengaging when told to do LSD things (like when autocrossing the car, it was acting like an open diff, way less traction than it should have had.) I had an indy shop look at it and said it didn't have any codes except for a diff control module historical code P186D-97 "Clutch actuator stuck" message. That said, I've also found an additional code in one of the other modules U0437-68 "Invalid data received from the rear differential control module" I think I've actually seen quite a number of communication related historical error messages - not sure if there is a common issue there to look for or not - if anyone knows that'd be appreciated! But yea, I need to have the diff looked at again to see if something needs replacing/fixing.

 

Here’s an older TSB related to driveline clonking.
https://www.dropbox.com/scl/fi/3rdom...=b8k2ggf6&dl=0

@Onca Engineering has a lot of experience with these differentials, especially LSDs.

 

mine is not making any whining for now, I wonder if the bushings can be replaced alone by themselves, but at that point might as well replace the whole diff, since I can still return the used one I got, I'm still in the 30 day return window in Ebay, got it for like $1600, I went with the used one since new one was like $5000 and $14000 for labor. now I'm down $1400 labor and possibly spend $6500 for new diff more bringing the total to $8000 almost in repair so far, which makes no sense to me to get it fixed, might as well sell the car at that point, and use the money I would have to spend on a different car.