If it is not your universal joints then you need to look at your brakes. You have disk pads for braking and brake shoes for the emergency brake. If that is not it then look at your wheel bearings.

 

I found that some of these cars tends to shift into 4th gear prematurely. Next time you feel that vibration / grinding, maintain your speed and acceleration and just flip the J-shifter into 3rd gear.

Report back

 

I had to get a rebuilt transmission for my 1998.

 

Hi , I am looking to see if this was ever reported as resolved. I have the same problem--(98 XK8 with 94K miles). Driving 30-50 MPH with a slight pressure on the accelerator I hear the grinding, maybe every couple of minutes, not consistent. As soon as you take your foot off the accelerator, it stops. The posts here say could be U Joints, could be transmission, could be torque converter, so I am wondering if this was ever solved with an exact fix. So far I have changed a bad wheel bearing (before I found this thread). I then greased my U Joints and it did not go away, but the car is 20 years old so wondering if they are too far gone.
Many thanks for your insights, as I HATE to take it to the dealer......

 

His last post says he replaced the transmission, so I expect that was the problem.

 

Do NOT take your 1998 XK8 to the dealership. Most Jaguar dealership techs these days know very little about our now near-vintage cars. You would be far better off with a good indie shop that knows the Ford-era Jaguars well....

 

Thanks All, I have one last follow up, then to find an independent transmission shop as suggested. The funny thing is that I turned on the sport mode (button up and light on) yesterday while driving, and the sound no longer occurs. Any suggestions on the symptom only happening in regular mode?

 

When I first bought my Jag, an '03 XK8, I too noticed some kind of noise seeming to come from the rear of the car, at speeds similar to the original poster, like 40 to 50-ish. One of the first things I did with this car, was to put on new premium tires, and get an all around alignment. As it happens, the '03 comes from the factory with different sized tires on the front and on the rear. Amazing but true, the previous owner had three fronts and one rear on the car. Once the new tires were installed, the rears were the same diameter, and the rear end noise totally disappeared. I might also note, that the rear alignment was so close to spec, that we decided not to mess with it. The guy who traded it in down at Palo Alto BMW was supposedly a "collector" .. so go figure. So if you are a new owner, don't be embarrassed to check what the heck you got for tires, before you move into the rear end or transmission looking for noise gremlins. Cheers!

 

@jon_welsh , if your noise seems to come from the center of the car near the firewall, then I have the same problem with my '97. Yes, it happens far, far less in sport mode, and it goes away with less throttle but it also goes away with more throttle, generally with a smooth shift to a lower gear. As the noise is happening I have no pickup. Does that sound like what you're seeing?

For an unrelated repair I had my car at AAMCO (one of the few mechanics in town I've found to work on it), and after a test drive they seemed to agree that it was a transmission issue. They reported back that they magically solved it... but turns out someone had just turned on sport mode.

So yep, after reading countless posts on this forum over the last year I'm pretty resigned to needing transmission work. Over that year of owning the car it hasn't gotten worse, but I've also had two transmission fluid changes and it also hasn't gotten better. I just drive around with sport mode on and drive with a heavy foot to avoid dipping into that grumbly region.

My plan, BTW, is to take the car to the import specialist who says he has a magic box that will diagnose the problem for $100 just in case it's related to some other sensor. I expect to be looking for a rebuild--or new transmission--once the specialist has had his crack at it.

 

I recently (last week) stopped using the sport mode and noticed that same noise you describe under slight load in highest gear (overdrive ?). If it shifts down out of highest gear then noise stops. Have you been able to resolve or find the cause of the issue ? Sounds like tranny to me and related to overdrive but I am not tranny expert.

 

 

Did you have some of the same issues reported here, where the noise would go away with gear shifts or was different in sport/nonsport mode?

 

 

I am bumping this older thread since I have had the same grinding noise described in several of the posts. My 1999 XK8 has around 75000 mile on her and as far as I know, has the original lifetime ZF transmission fluid. I, too, found that the noise has disappeared since In turned on the "S" button on the console. In regular mode it would consistently occur at around 35 mile per hour with no load just as others have experienced. I have some questions:
1. I plan to have the ZF fluid replaced and understand that there is a MERCON fluid (or some other brand) that will meet the specifications and is not as prohibitively expensive as the ZF fluid. Does anyone know what that fluid is?
2. When I have the fluid replaced, I know the pan will have to be dropped and replaced since the filter is built into it. Isn't there a "fix" for the notorious A-drum before it fails and where can I get it?
3. Anything else I should consider having done while the pan is off?
4. Can someone explain in layman terms why does the grinding noise go away in "S" mode?
Thanks,

 

Here's a half-informed response for someone with the symptoms but without a proper diagnosis:

I've had the symptoms for about a year, and I've had two fluid changes, the first as an intentional change and the second in the course of repairing the rear main seal. The symptoms haven't gotten any worse, but the fluid changes didn't have them get better, just to temper expectations.

2. I believe work on the A-drum would require removal of the transmission, not something that can be done during just a dropping of the pan.

4. For me the grinding happens when the transmission is on the border of a gear, like it's just on the border of deciding it needs to drop into a lower gear. Maybe that means more stress is being put on that clutch? It seems like "S" mode changes the shift pattern so that the transmission isn't on the fence about downshifting, it's already downshifted at that point.

 

 

Looking for answers to this phenomenon as well. It is a grinding noise BUT I also got the impression that it might kinda sound like fluid being pushed thru a small orifice at super high pressure. Not sure.

I was driving this same car WITHOUT this noise before an engine swap I completed about a week ago. I had never heard this sound before after 3+ years of regular driving. Also replaced the 4 rear half shaft universal a month ago as well as rear shocks and brakes. I am interested in the possibility that is the E brake, and will check. Thanks Gus


I had been taking it easy on the trans and engine after the swap bit yesterday got it up to highway speeds and 5th gear/overdrive for maybe the first time. That's when I got and get the noise. Sounds like (if I could tell) it's coming from the back section of the trans tunnel area. It's short in duration but will come and go predictably with giving throttle. It don't sound good. I could add some fluid and see how that goes. I would love a definitive... Anyone find one?

It's a very uncomfortable feeling to to be hearing something like that when doing 50, 60, 70miles per hour.

 

I had the exact same problem only between 47-50 MPH and my mechanic fixed it with sheet metal screws. It sounded like a tire rubbing on the plastic liner - or worse. He knew what it was as soon as he heard it. His diagnosis was that a piece of the honeycomb structure inside the catalytic converter broke off and is resonating under the pressure created only at a certain speed. He's seen it many times on older cars. His solution was to run some sheet metal screws into the cat to secure the honeycomb and that solved it! Much better than replacing the cat!

 

Interesting...Could it really be?

Interesting because my converters just went thru some knocks and bangs. Not quite sure what to do now... Hmm

 

This issue has been resolved( sort of) by activating sport mode. The noise does not occur in sport mode and has not occurred in sport mode for over a year! Weird, huh?