Fellow enthusiasts...
I've been having this imbalance at the rear of the car; thought it was due to the cheap winter-tires but now I changed to summer tires it's still there.
It feels like wheel imbalance but if anything at a slightly larger speed range.
Imbalance starts quite abrupt at 70 kmh, get's less after 75 kmh hardly observable after 80kmh.
It doesn't seem to be always there or same severity but can't make any logic out of why (ie cold weather, wet, long drive, etc)
I've heard failing suspension bushing can be causing this, any thoughts/experience on this forum?

Thanks
Han

 

I bought a FWD X-Type with that issue back then. I think the vibrations started at 75 or 85 km/h and did not get less at higher speeds (mind you that the highest speed here in Australia is 110km/h.) I fixed it by replacing the the complete frt. drive shafts, left & right. I had them shipped in from Germany, as they were sold out in Australia. Maybe it would have sufficed to just swap the bearings - that is something I'll never know. And since the S-Type is a RWD, it could well be the same issue in the rear... I read not too long ago here on this forum that someone had the same issue...

 

Thanks for your reply.
This is interesting, having replaced the rear diff because it was whining I did notice the splines that go into the diff being a bit worn. Discussed with the garage mechanic and refitted them.
I am now questioning myself if this has been a smart thing to do.
Can worn splines cause a diff whine at 100kmh?

 

I consider 100k km a very low mileage. All my cars have more than that on the clock. I have not replaced any rear diff so far. I never heard of worn splines either.
If you would have asked me back then, what to do about noises coming from the rear diff, I would have said: Change the fluid in the diff:

https://www.jaguarforums.com/forum/s...s-type-264126/

That's what I did, as you can see in the thread above, even though I did not have a whining diff.

 

Thanks again for thinking along Peter.
I did change the diff fluids first (also added additive), this made no change to the whine hence replacing the diff.
Maybe I should have a closer look at the splines of the removed diff to check for wear...

 

First things first go get your tires road force balanced and make sure they can get them under 20 pounds then post back if you still have the vibration

 

CV joint? Have any of your CV boots split in the past or present? If so, ingress of dirt may cause premature wear.

 

This is the plan, will need to do periodic maintanance amyways.
Will make a list of items to do... 😅

 

Have the tires rebalanced and while it's spinning look and see if the wheels themselves are bent and wobbling around or turning straight and true. If you have to get a new wheel or two, check them on a wheel spinner before you buy. I've had problems with bent wheels in the past.

 

No mention of miles??
I would first check the Guibo. That's the rubber disc between the drive shaft and the rear end and transmission. Note this is NOT serviced separately by Jaguar BUT it is the same as used on several other cars such as certain BMW models. Sometimes called a drive shaft damper too. They are available in the aftermarket.

Here is the guibo and the drive shaft so you can see the massive difference in price! This is for the 4.2L S-Type.
Jaguar Drive Line Parts

These can loosen up and the rubber can tear and in general age starts breaking it down.
Here is a good thread but for the XF model.
Guibo Replacement

Note this problem is more common on higher HP (STR!) cars so with the V-6 this may NOT be your problem but do check the rubber.
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Thanks for the replies, this is much appreciated
Maintenance has been postponed due to holidays, so no update for now.

The car has now done 108k kms.
I have not observed any issues on the Guibo when I changed the diff some 5000kms ago

What I did observe is that the imbalance seems not to be the same all the time; sometimes i't pretty rough, sometimes hardly noticeable.
This weekend I plan to check play in the suspension and check the Guibo (and continue rust treatment of rear subframe).
I also plan to exchange front and rear tires to see if anything changes.

Thanks again,
Han

 

Some progress...
Upon investigation found Guibo to be ok.
However both lower control arms had ripped bush seals and one side had some play on the outer bush.
Ripped seals are a definite no-no for periodic check due in 2 months.
So I have ordered two lower arms as I didn't feel like going through the hassle of replacing bushes.

Hopefully this will get rid of imbalance... but would need to be done anyway so we'll see
Will report back.

 

Have you had the Tires Road force balanced?

Changing out suspension parts is fine and all but have you looked at the tires to see if they’re still balanced?

 

Pardon my ignorance, but what is a ‘guibo’?

 

I did not know either when I read this thread days ago, but I imagined it to be the rubber dampener in the drive-shaft-line.
But since you asked, I just typed the word into google to know for sure, and that's what it is:
https://en.wikipedia.org/wiki/Giubo

PS: GIYF (google is your friend)

 

Aha. Most enlightening! I’ve never heard it called that. I’ve always called it the rubber doughnut. In future, when I go to the supermarket I will ask the baker for a bag of 5 giubos! 😂

 

It's an odd word and I think it's German?
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Nope, it's not German, but again: GIYF:

Giubo is a portmanteau of the Italian words giunto ('joint' or 'coupling') and boschi (the surname of the Italian engineer who designed and patented the first flex disc, Antonio Boschi (1896–1988)).

Also: A giubo also known as a 'flexdisc', and sometimes misspelled as guibo

 

Thanks for this information Peter, fun facts...

To get back on my issue after my holiday in the Alps.
Ofcource Aarcuda is right about first balancing the tires, I just didn't have time to get it done.
Yesterday I did some periodical maintenance with help of a real mechanic.
Wheels balanced (all had minor imbalance), replaced rear lower control arms and trialing arms (again, they needed to be done anyways).
First drive shows significantly reduced imbalance however stil noticeable at 70kmh.
Will accept this for now and see what future bring as it didn't seem present all the time beforehand.

On a side note, due to available info on this forum I was able to spot 2 loose shifter bolts on the side of the transmission and also replace OMT seal that looked a bit dodgy.
So cudos to you guys!

 

Almost 2 years on...
Got fed-up with the imbalance; talked to drive train specialist was adviced to have drive shaft balanced.
They took a look; all links looked fine, spline where 2 halfs meet was very good, hardly any play, also center bearing in fine shape.
Imbalance in the shaft was minor, but corrected.

I fitted the shaft and there seems to be more imbalance now?!
Must say I am quite gutted...
Planned to use the car for holidays, but this way it is undriveable.

Imbalance is very slightly noticeable under 60kph but at 60 comes in quite sudden and hard; above 80kph seems to get less. At 100kph it is ok-ish.

The (pro) tech at workshop had disconnected the shaft and towed the car at 70kph (engine running), no imbalance noticed. So doesn't seem rear drive parts related.
I am aware that by disconnecting the driveshaft, no force is put on diff and axles, but since different pedal positions don't seem to matter this seems legit conclusion.

Guibos seem ok, solid but flexible.

According to manual for alignment of center bearing there is a special jig. This was now done with a piece of string but seems quite well.
I could not find anything else when it comes to placement of center bearing.
Not sure how critical aligment is; anyone ideas experiences?
The tech mentioned that some other brands require some form of pretension on the bearing, but I did not find anything for the S-type.

Any more suggestions please?
Tech suggested to find other drive shaft and fit this.
personally I was thinking about finding an other guibo disk see what that does.
I am getting a bit desperate.

Car has now done 138k kms
Wheels balanced.