The car exhibits a fairly heavy vibration (with one possibly unusual feature). It commences at 60mph and continues until 90 or more. The vibration is felt on the seat and through the steering wheel, and can even make contents in the door pocket rattle.

All four wheels have been balanced, and none of them needed excessive weights which, the fitter informed me, would have indicated a warped wheel. So I am starting with the assumption that the wheels and tyres are undamaged and properly balanced. There are no transmission or suspension sounds and, other than the vibration, the car drives very well. The vibration happens whether accelerating, decelerating, or coasting.

The unusual feature which I think happens is that, if at a lower speed (say 40 or 50) I go over some uneven surface or a shallow pothole, I get a hint of the same vibration, as if it starts and attenuates quickly - starts and rapidly dies.

Could it be a Universal Joint problem, or do you have any other thoughts? I think that what I am about to say is probably absurd, but the transient lower speed vibrations do make me think of an active suspension issue, though I can’t imagine what - so please send me barking up the right tree.

 

Drive shaft coupler, u-joint, out off round or warped wheel /tire, wheel bearing for starters

 

Thanks. Would the wheels balance with normal weights if the wheels were out of round or warped? The tyre fitter said not ( but I would be more inclined to listen to forum members)

 

Unfortunately, I disagree with the drive line diagnosis. The reasoning for that is the low speed uneven surface response. Since it will start and the attenuate it is a front end steering/suspension problem. Drive line vibrations will most definitely be felt thru the seat but the vibration shouldn't transmit thru the engine to the steering wheel.
So you need to get it up on a lift and remove the front wheels and start inspecting:
1. Check for play/movement at the steering arm connections. There should be none.
2. Inspect the condition of the lower shock absorber bushing. Should be no movement.
3. Inspect the upper shock mount condition for collapse. I almost for got before lifting and removing wheels measure the "ride height" center of the wheel to the lip of the fender distance. Record and report back what you have for a measurement.
4. Grasp the brake rotor at the top and bottom ad try to rock it back and forth. Should be no movement in that direction.
5. Check for any play in the upper and lower wishbones mounting points by trying to pry them around . There should be know movement.
6. Last for now examine the condition of the sway bar links for movement and check the condition of the sway bar bushings.

Take a close inspection and get back to us.

 

Thank you for these two really useful replies. Before following them up, can I ask for your thoughts on whether (even though I have been assured that wheels and tyres are ok) it is worth changing them, just to see? They are 20” Sepangs, and I actually have a complete set of four wheels and tyres I could swap into the car.

At any rate, I will get onto this, though can’t do so right now. When I have a diagnosis I will report back.

 

Well you could swap the wheels. Balance or out of round usually shows up in the front wheels first. If not wheels, it could be the drive shaft or u-joints.
Let us know how you get on changing wheels. That's a first step that won't cost anything.

 

That is the kind of cost I rather like! Actually, I bought the set before moving to Portugal for exactly that reason - should I have a wheel problem it would be virtually impossible to source a matching replacement here.

 

avern1 and JimmyL are on the right path. Just a little time and no money spent to investigate what the real cause is.
I have similar issue with the steering wheel shake at speed with a rattle over smallish bumps. I have a full set of bushings, wheel
bearings and ball joints ready at hand. I'll do one corner at a time to satisfy my curiosity. Keep is posted.

 

I used to have this and it was a combination of this and that,,, that I to date have not completed fully, yet... But this solved a LOT...

If you look at the back of the lower subframe,,, say you have the front wheel off the car and are looking towards the back rear corner of the well,,, you will just barely be able to make out the rear subframe mount. It will be where the more silver subframe meets the body/chassis. Would be kinda where you tootsies would be, lol... They go unnoticed and are rarely talked about.

Mine were essentially flat and in that, fairly unstable. It took a LOT of force to exhibit symptoms,,, usually for me at about 67mph, til about 80, where the jelly feel and vibration up front would stop. Bumps on uneven surface as well, especially when turning...

Just look at them, I'll post a picture. You'll know if they are shot,,, if you are able to imagine what they would look like healthy,,,, with the limited near 2D view your going to be able to get of yours/them... If they are flattened out, it ain't pretty... Sometimes the sections can separate too, which can't be good.

I'll offer an approach at changing them if that's what ya think it might be... The WORST and only tough part of the job is IF the crappy torxs bolts jaguar used to attach them to the subframe strip out upon turning them out. What a stupid choice of faster... I digress

 

Sorry... I gave a terrible description of where they are located...

This, I think, is just under the wishbone, backside, where the steering rack and steering arms poke out of the rack... The other one was worse than this.

I'm still gearing up to do the front mounts which,,, how bad they ARE,,,, is only pronounced by doing the rears over the late summer.


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Blimey.

Having read all these interesting and informative posts, for which many thanks, wouldn’t it be great if it was merely a wheel problem. Somehow, it doesn’t truly ‘feel’ like that, if you know what I mean.

 

I do...

There's a lot that has to "come together" in that doggone front end... Freaks me out sometimes...

 

Hi Diddion,

You've received some great replies already. I just wanted to chime in that as I was reading your thread, my mind was going to the front subframe rear bushings or "Vee mountings" as Jaguar calls them, and sure enough, JayJagJay mentioned them. When those bushings perish, they allow the front subframe to rotate on its vertical axis, and at certain speeds oscillations can develop, with the subframe literally wiggling right and left. Since the steering rack, control arms, etc. are bolted to the subframe, and the subframe is bolted to the body, you feel these oscillations in the steering wheel as well as in the seats.

I read your account of the low-speed behavior twice to see if there might be a clue there, because one of the symptoms of Vee mount failure is tramlining, where the car tends to follow road surface imperfections by pulling to the left and right. Have you noticed any behavior like that?

Cheers,

Don

 

Thanks, Don. Definitely no tramlining at all. The steering and suspension are taut and precise, as is the braking. The single symptom is the vibration which commences at 60, with those ever so faint transient vibrations at lower speeds, in response to road unevenness.

Note. A good list of possible causes and solutions is building up here, from the cheap and trivial to the more complex and painful! As I mentioned, I will not be able to get onto this for a few weeks, but it is really handy to have this road map, so thank you everyone.

 

Also put on your checklist the engine mounts.

Cheers,

Don

 

The vibration is does not alter noticeably with engine revs, and is not linked to whether power is being applied, coasting, or engine braking. Would not those factors tend to point away from engine mounts?

I am reminded of a funny story. I once called a family guest into the bathroom of my house to help me locate a strange and fairly high pitched vibration. With a look of disdain he reached over and picked up, then switched off my electric toothbrush. Now the XKR vibration is somewhat lower in frequency, indicating, perhaps, a rather larger, heavier object, perhaps dropped somewhere having fulfilled some use or other. I just can’t think what it could be, if we discard, for now, the various posts above. Any thoughts......?

 

I believe you when you say everything is tight. For one, it's because everything else can be tight and probably is for the Vee thing, to suck. Two, is because I would expect all of those things TO BE tight,,, because you seem like a guy that takes good care of your car...better then me, I'm sure.

I don't mean to have tunnel vision, or to stay stuck, against clear and obvious evidence against my theory,,, but everything else can be (and feel) tight while the vee mounts (thanks Don) are failing or failed. As far as you know, have they ever been changed? When I first got to the forum, I read a lot, and I rarely hear them mentioned, dispite (as Don pointed out better than I ever could) the many suspension components they have an huge impact on.

If the rears are bad and never been checked, the front ones (like mine are now) should get attention too. And,,, the symptoms show up,,,, sometimes...

Before doing mine (and I still have a lot more front end work to do) the tramlining wasn't showing up,,,, much. What it often took were the terrible way NYC roads can be indented in predictable areas,,, where on asphalt,,, a million tires have passed,,, literally making embankments in the road,,, that kind of resemble paths made on dirt roads by covered wagons. Before doing my vee's, when one of my front tires caught that Grove just right,,, I would be all over the place... I was shocked by how much this lessened after the swap... Let me guess,,, you're in one of those places in the world with smoooooth roads, lol hahaha...? I dream of smoooth road. OMG...

As for the toothbrush story,,, I GET IT!!! do you keep your phone in your pocket, on vibrate, when ya drive, lol????

 

Actually, the toads. (Should have written roads, but the typo is rather nice, so I have left it in) in Portugal are surprisingly good, other than cobbles in towns. Before coming to Portugal, a couple of years ago, at a distant time when I was financially flush, I took it to a very good Jaguar independent and asked them to do everything. They did a huge amount of stuff, including various suspensions and mounts, to prepare for a leaner and tougher future. So basically most normal things would have been covered. Subsequent degradation is more likely to be due to the very hot weather in summer, rather than wear, so I would expect that rubber mounts and so on could be particularly vulnerable - hence your suggestion is well received.

What about the order to address the suggestions made in this thread? I propose wheels, followed by drive shaft joints and wheel bearings first. Then, what would the most sensible order be for subsequent steps, anyone?

ps. I have got to say that I will be HUGELY EMBARRASSED if it turned out to be a wonky wheel. Might even be tempted to provide an alternative fact or two when I report back.

 

Engine mounts don't always manifest themselves when the transmission is in Park, but I would expect you to notice some association with engine speed while in gear and under load if an engine mount was the cause of your vibration, but since the mounts are hydraulic they may behave a little differently from standard mounts, so it's worth checking them for signs of leaks.

Another thing I'm not sure anyone has mentioned yet is the transmission mount/rear engine mount.

One other thought is the possibility of a tire with internal damage that may balance fine on the low-speed balancing machine, but may vibrate at higher speeds.

Can't wait to see what you figure out. We'll all learn something.

Cheers,

Don

 

Hmm. Cheap or free things first... The bearings you 'should" hear, although I've never had one fail and don't know if it makes the noise a failing bearing makes on most cars I've dealt with... Like, at speed on the highway and you'll hear a high, low or medium pitched him... Wheels, just go to a tire shop. I guess I'll have to read back to remember all the mentioned items.

Sometimes, I've heard and am experiencing now, the space between the pin and the upper wish bone and the subframe itself can get sloppy. Like, the hole that holds the pin in the subframe actually wears out, goes out of round, for jaguars poor choice of having a steel pin work against an aluminum subframe,,, in an area that experiences more regular force,,, than almost any other component of the car. Bad design. Anyways, mine is that way now and the fix is either a steel cuff insert and drilling the subframe hole larger or replacement of the subframe. Had to find a 'new' subframe these days.

I hate to add to the list,,, but there are just so so many bits and pieces...coming together for a smooth all time ride.