I've pretty much eliminated all other possibilities for a wow-wow-wow noise that is speed dependent, and whilst not too loud, is starting to diminish my enjoyment of the XF.

To troubleshoot, I've changed all the tires to brand new Conti DWS-06's with Hunter dynamic balancing and had the rims checked for trueness. I've manual checked for play in the wheel bearings, so I am starting to worry that it might be the differential. Of course the car is an early 09 in the 25xxx VIN range so the older gen-2 diff with potential issues of contamination at the factory. I've been talking to Quaiffe and whilst it appears the QDF3W is an option, it relies on the donor differential being serviceable (or at least having serviceable seals, crown wheel and pinion), which is unlikely given the root cause of the problem. BTW the diff is bone dry and had a recent oil change with no audible change in the noise.

So I'm looking for help, options and moral support!

First is to take it the to dealer for a diagnosis, which I plan to do. However there is no way on earth I am paying $8k+ for a new diff and half shafts due to a design change and what I consider to be negligence on Jaguar's part in letting contaminated diffs out in the hands of customers. In my eyes this should have been subject to a recall, but this is probably moot at this point. The car was a Select edition and the TSB says fix before sale so I might try to push that angle.

Second is to look for a used diff. Of course there's no guarantee that the used on won't have the same issue, but it is certainly worth a try. I'd probably have to go independent for this. Does anyone know the if the XJ8 (X350) and S-type R (X206) diffs are interchangeable? Most information seems to imply yes, but I'd love to hear it from someone knowledgeable about such things?

Third is recondition the Diff. Does anyone know how easy or feasible this is? I know Jaguar normally considers things like the diff as sealed for life, etc. but in this case, the diff seems to be relatively common and I suspect it could be rebuilt by a competent independent transmission specialist.

Thoughts & ideas and brainwaves are most welcome.

Thanks

- Tim

 

Read this https://www.jaguarforums.com/forum/j...ntials-134733/

And this https://www.jaguarforums.com/forum/x...r-diff-143980/

And this https://www.jaguarforums.com/forum/x...arings-102296/

These diffs can be rebuilt with new bearings and seals.

If you're looking for a used diff make sure you get the right ratio, your XF SV8 has a 3.07:1 which was only used in the XF SV8, S-Type 2.7 diesel auto, and the 3.5L X350 XJ8.

You won't find a S-Type 2.7 diesel auto or 3.5L X350 XJ8 in North America. But they were available in the UK, EU, and pretty much the rest of the world.

If you want to change the ratio (because a 3.31 will be easier to find) then the car needs to be reprogrammed, and a dealer won't do this for you, even though he has the necessary tools to do it. It's not impossible you just need to know the right people, I don't know anyone in your neck of the woods unfortunately.

If you're going to swap ratio's then a cheaper and I feel more bulletproof solution is the diff and driveshafts from the 4.0L V8 S-Type, and it already has the 3.31's in it, and a regular Ford 8.8" 28-spline LSD will bolt straight in. You can see the differences between the Gen1 & Gen2 in the Overview of Jag Differentials thread.

 

Thanks Cambo, very useful information. One quick question, what is the effect of changing the ratios and not re-programming? Speedometer off? Incorrect fuel consumption numbers? Faster/slower acceleration? Cruise at higher/lower RPM? Cars are not my thing, if this was a computer or a piece of test and measurement equipment, I'd be all over it....

I've been looking for a rebuild kit, so far without success. I suspect it will need new crown, pinion and seals (even though the current ones are not leaking). Any thoughts on where to get the individual rebuild parts?

 

Ratio swap without re-programming = limp mode, you won't be driving the car anywhere.

You used to be able to buy ring & pinion as spares from Ford for the Lincoln LS (but not in your ratio unfortunately). So I think you will struggle to find them new.

Seals can be ordered from Jaguar as spares.

The bearings can be sourced from bearing suppliers (the part numbers were in that other thread). The lock nut and crush-tube are standard Ford 8.8" parts.

Mu understanding is that the diffs with the swarf contamination chew out the bearings, but the gears are generally ok. (I may be wrong though, I do recall someone mentioning this on the forum).

 

Thanks again Cambo. Let's hope that it is just bearings. There is a local transmission and differential shop who comes very high recommended. I'm sure that if they can get the parts, they can rebuild the bearings, assuming the gears are OK... That link to the rebuild has all the parts I hopefully will need. 1000 thanks!

BTW I looked on both ebay UK and ebay US, not a single diff for my car. OMG!

 

I just happened to be on Ebay, and saw seller LKQ selling several used units that appear to fit your car. I believe the price was in the $650 range.

 

Yes, I saw that. Honestly at 104K miles for the LKQ Diff and only 60k miles on mine, I'm not sure it makes a lot of sense. I suppose I could buy it and rebuild it at my leisure and then swap them over....

 

Arrgh, so just got a call from Jaguar. Classic good news/bad news. Turns out after a lot of investigation that it is a bad rear wheel bearing and not the diff. It took them a while to figure it out as the bearing was not showing any signs of wear.

However in a classic case of Murphy's law, the service adviser said, "did you know your AC is not working?" I was basically WTF, that A/C was working fine when I dropped the car off 3 days ago. Awaiting diagnosis of what the problem is now....