I've seen mention of the issue that ultimately requires a new e-diff for a gazillion dollars. But how many XKRs actually develop the probnlem? And is it a manufacturer defect or the result of overly enthusiastic driving?

 

Hi Chazaroo,

I have a XK from 2007 and the diff makes a whisteling sound. Most of the time you can't hear it because of the motor sound (so it is quite a soft wistle).

I have been at the dealer and they say that it's a knows issue but replacement is'nt nessecary. If you want it replaces than also a part of the drive shaft has to be replaced (or issue will come back after some time).

I also had an 1999 XKR which already had 2 diffs replaced.

I think that it's manufacturing defect. They probably harden the complete gear (so the top of the "theeth" also get hardend which makes them inflexible). And overly enthusiastic driving does not help in reducung the strain on the diff.

 

The XK does not have the E-diff. It is an open rear. I also believe the e-diff started with the 5.0L XKR series cars.

 

I also have the whistle. It happens at exactly 1750 rpm and only when you are lightly on the gas or decelerating off the gas.

 

My '07 XK has more of a howl, sort of pronounced about 40 MPH, and likewise it's more noticeable as you take your foot off the gas. Recently I've noticed it's become louder at highway speeds when the top is up. An indy told me there wasn't much that could be done about it, so just run it until it fails (hopefully that's not the middle of nowhere).

 

I'm pretty sure the OP means the shudder-like feeling when turning sharply from a standstill.

 

Agreed.

 

I had no idea the 5.0L supercharged XK had a rear diff issue. I will be more keen to listen for a whistle or feel for a shudder

 

Exactly right. I've seen some posts about this and am curious how common the problem is?

 

I believe your estimate is way over the top chaz. They're only around half a gazillion so let's come back to earth shall we?

Actually I saw the comments recently too and though I don't own one, I haven't seen a lot of issues about them on this forum.

It would be great to get a tech to weigh in. Brutal, you out there?

 

The "shuddering" issue, and I say issue not problem, is commonly reported, and my car has had it since I bought it over 4 years ago. And the reason I wouldn't call it a problem is because it has no practical effect on anything except for a millisecond's worth of that "shuddering" feel usually when making a left turn from a stop. I have somewhere around 140,000 miles on my XKR and there is no other symptom except for that and no other problems associated with it.

 

LOL! Is that half a gazillion US or Canadian?

 

Changing the diff oil usually makes the shudder go away. I used Jag diff oil, expensive for diff oil but it totally cured mine

 

Does it vary with road surface (if so, usually pattern noise from the tyres) or when turning (if so, usually a wheel bearing)?

If it is the diff, it should stop briefly as your car moves from power on to overrun, or for longer if you can manage to hold it in that driving condition by careful use of the throttle on a level road. If it is the diff, I assume it's just normal wear; what mileage has your car done? Try changing the oil, and add some Slick 50 (or whatever it is called in the US) for Differentials to the new oil. That should at least quieten it down. Unless, of course, somebody knows different...

Whining differentials will usually go on for tens, if not scores, of thousands of miles. They just get louder and louder until you can't stand it any more!

TN

 

“When I look back on all these worries, I remember the story of the old man who said on his deathbed that he had had a lot of trouble in his life, most of which had never happened”

Winston Churchill

Dont keep your worries from enjoying your new bride- she is older than she looks- which should be your only worry.

 

Nope.
Yes, easing up lightly on the gas and it stops.
Got about 45000 miles on it. It's howled since I got it at 38000. Had the indy change the oil, with no change to the howl. Have to consider an additive.
The howl would probably drive me bonkers on a cross country trip.

 

I feel I am hijacking this thread, but does anyone know of any additives that can silence the differential?

 

Gin.
But please follow local laws.

In your specific case- and ONLY in your case. I would try the Amsoil gear oil and lubegard.