I recently replaced my 2009 XF with a 2009 XJ to get back the ride that I loved from my prior XJs. After driving this car for a bit, I believe there is something fundamentally wrong with the suspension.


When I'm driving over 30-40 MPH, I notice that road imperfections will cause the car to rock and roll much more than any of my prior Jags. It almost feels like the car is on its tip-toes, with no room to absorb the road imperfections. But it doesn't manifest as a stiff ride; it feels more like the vehicle is getting rocked. If I had to guess, I'd say that it *feels* like it's originating in the rear, but I'm not certain.


Yesterday I was driving it and feeling this sensation on the highway at about 75 MPH. I disabled DSC, and while I didn't get a perfect ride, I really feel that disabling DSC improved the ride / reduced the rocking. When I re-enabled DSC, I felt the rocking again when I hit uneven pavement (e.g., transition from asphalt to concrete pavement at overpasses). But who knows; maybe I'm imagining that correlation.


I've read through the ECATS descriptions posted here and it seems like this could be an ECATS issue, but I'm not sure if DSC is related to suspension at all or if it's just related to wheel spin.


For what it's worth, the car is lovely smooth on smooth pavement; I don't ever hear or notice the compressor running; the ride height appears correct; when pressing on each corner of the car when stopped (in gear, but foot on the brake), the car feels quite stiff.


Any thoughts? Scared to take to the dealer without some education behind me.


Thanks,
Doug

 

You won' get the "Magic Carpet" ride of the old XJs from the X350, the suspension and general set-up is totally different. The suspension is a Ford-developed system used on the Lincoln LS at the time the X350 came on sale, (2003). So, as you describe, it is nice and smooth on well maintained tarmac, but knobbly on other, badly maintained, roads. What doesn't help is the fitting of large diameter wheels with low profile tyres. The old XJs had 15" and then 16" with "balloon" tyres. These absorbed small imperfections in the road surface that the modern stuff doesn't.

So you're probably asking why the hell use these large diameter wheels ? Well a huge percentage is this modern mania for "Sport" and "Handling" as if every Jaguar owner drives round a motor racing circuit every weekend. I for one do not, and would love a return to comfort, or at least the option of having it again. You can obtain 17" wheels, the smallest fitted to the X350 cars. Most will be used as I don't think they are available new now.

So, what is the diameter of your wheels on the car ?

 

Fraser, I completely understand the wheel size issue. My XF Supercharged had 20" rims, and before I dumped it due to the rough ride, I contemplated selling those off and putting on 18" rims. Someone on this forum kindly pointed out that the oversized brakes on the Supercharged model wouldn't tolerate anything smaller than 19", and I didn't have enough confidence that the extra inch would return me to the ride of my 2002 VDP (still the best driving car I've ever owned).

And in fact, I intended on buying a 2011 or 2012 XJ to get the much more attractive (to me, anyway) body style. But I was very disappointed that the X358 ride was very stiff, like the XF. The dealer also lamented that I had to stick with nothing newer than 2009, stating that the X358 updates were geared to a younger buyer that equated performance luxury with the more aggressive German ride. Idiots.

Anyway, while I get that the X350 (19" rims, by the way) may not match the X308, this isn't roughness. This is driving over a pavement irregularity and having the rear of the car (I think) rock back and forth. Two years ago I bought a 2004 X350 for my wife's parents, and that car doesn't do this. Something is wrong.

 

take it to a good alignment shop. Check the inner lower control arm bushings. While there the rear toe adjusters. Finally rear sway bar links.

 

Might be worth scanning the vehicle.

There might be codes that will give a clue if there is an electronic fault.

 

Check upper and lower control arms and toe links. They seem to be worn.

 

Does the x358 have a DSC button? The x350 only has a TC on/off switch, which should not have any effect on the ECATS functions or ride of the car. I'm not sure DSC is able to be turned off, as it is a safety function of the vehicle.

You may have a faulty body accelerometer in either the front or rear that is throwing off the ECATS, but I think that is on the outside chances of being the problem. The ECATS is not that sophisticated. You generally get a ride that's bone-jarring hard when it's stuck "on" along with an "ECATS FAULT" message on the dash. When the car is at a stop, the shocks default to the firm setting, so pushing at each corner when stopped you will not notice much deflection. The shocks are very soft once you are moving.

I can say that the difference between the x350/358 with 19" vs 18" rims is stark. Test drove one with 19" and felt every grain of sand in the road. The 18" made a huge difference.

 

Hmm...
My previous X350, a 2003, started off with 20" Sepangs which I soon dumped for 18" and the ride was a lot better, but still rather harsh. Then late last year I swapped it for a 2007 Sovereign on 19" wheels. I have to say I don't notice any difference between 18" and 19". However, I think a lot has to do with the tyres. Mine came with some Chinese ones called "Goodride" on the rear, and Pirelli P-Zero Asymmetrico on the front. If only one could find out which tyres give the best ride. Anybody have any ideas ?

 

Since no one has mentioned miles, I can say that after I changed my original air modules with Bilstein B4's, the shock performance change was very noticeable. (115k miles) Part of eCATS is detection of undulation, by using both yaw and height sensor computations, which can change shock performance from comfort to sport mode (soft to hard) of front/rear/side PWM in pairs to try to eliminate it. Both the X308 and X350/X358, on the right road conditions do exhibit undulations. (there are comparison videos on YouTube when the vehicles were released and compared to other luxury sedans/saloons)

 

I'd check all the anti-roll/stabiliser bar linkages and bushes, both front and rear.

 

must admit when comparing the Jag to lets say a BMW F 7 series the BMW is suspension wise way ahead. Have changed the whole bushings ball joints rod ends etc. on the car to make a refresh. quite some bucks in the parts but what is done is done. there had been improvements but you wont get that perfect ride of any modern luxery saloon. also of course the big rims don´t help that much. i big and for free improvement had been to get the car to it´s factory ride height. had meine lowered on the fronts to the same as on the rears 373mm and can say with getting it up to 386mm on the front made quite an improvement.

 

I've noticed this sometimes in my car (2004 XJR) but it doesn't stay that way. It will "bounce" maybe three times and then settle out.

 

I think it's time to go to the dealer. I drove it again today and it's definitely a side-to-side rocking, I am pretty sure it's initiated at the rear, and it definitely *feels* less prominent with DSC disengaged. I could write a song about how much I hate the large wheels and the low-profile tires, but the XJ really does a great job absorbing most road imperfections that would've been transmitted directly to me in my XF Supercharged. But send one side of the XJ up with a pavement transition and is does this squirrely side-to-side rock that even my Durango doesn't do. Thanks for all the suggestions; I'll re-post when I get a good diagnosis -- or not.

 

My 2 cents, check the alignment! I see others have mentioned it already and I support that idea. When I first got my XJ, it would do basically the same as yours over some pavement (usually rough or uneven) and level out on smooth roads. In my case, I checked my alignment (DIY at home) and it was all messed up. Both rear wheels were toed to the right and the fronts were both toed to the left (by lots, like almost 1/2" out, no idea how that happened). I adjusted it all back to spec and guess what, no more rocking/shaking/whatever over bad pavement. Due to the air suspension on these cars and how it self levels, I find that even when the alignment is WAY out (like mine was) the steering wheel will still be basically centered and the car doesn't even pull to one side or the other. Great setup for smooth driving, bad for noticing if your alignment is off. But you do get those odd side-to-side, or something similar, movements.

 

The Jaguar Enthusiasts Club had a one-day seminar on the X350/358 last year, given by David Marks. In it he said that for the 350 it really pays to have all the alignment and tracking adjustments etc, front and rear, spot on and not simply within the tolerance bands.

 

Thanks to all so far; still no joy. Took the beastie to best local alignment shop that I know and they report a) all suspension rubber appears solid and intact, and b) all four wheels are within spec. To Partick the Cat's comment about being 'spot on', of the 14 measurements they took, 4 are edging closer to one side of the tolerance band than the other; the other 10 are almost dead center.

The guy at the alignment shop said that his MDX behaved this way when the shocks were just simply worn out. And my mechanic examined each shock with the wheels extended to look for any signs of leakage; there's none.


With my car stopped, each corner is very stiff. Is there any way that I can simulate the 50 MPH shock state when the car is actually sitting still? This is my last hope before breaking down and heading to the dealer.

 

My 2008 XJR felt the same way. Upon inspection all rear brushes were shot. I replaced the entire rear suspension components (CAs, etc) with the exception of sway bar bushes. Now the car feels solid when compared.

 

Maybe subframe bushings?

 

Well, I've been driving the car on & off for the past two months without having had an opportunity to hit a dealership. For whatever reason, the problem seems to be gone. Gone. Very weird.

Before I bought the car, it had been sitting on a lot for over 9 months; is it possible that some sensor or other part got 'stuck' or something for sitting so long, and now it's responding properly? I'm sure confused, but not unhappy at all. The car is driving beautifully. I'm hoping it's going to stay this way.

 

Another update: shortly after my 6/2017 post, I noticed the problem returned. Took it to the dealer and they diagnosed it as a front shock problem (although no leakage was detected), and they said the lower control arms had too much play. I kindly paid them $150 for the diagnosis and had my local mechanic replace the lower control arms. No change. I wasn't ready to pop for front shocks in hopes that it would fix the problem.

Both my mechanic and the dealer noted that the tire sidewalls had significant checking, despite the fact that the tread was still excellent. Not one to be interested in flirting with a high-speed blowout, I dropped $1200 on a set of Pirelli P7s and... the problem completely disappeared. Everyone is baffled.

The car had been sitting 9 mos. at the dealership before I bought it, and who knows how long before that. The only thing I can think is that the aged low-profile sidewalls were stiff, and transferring more road imperfections to the suspension than it was prepared to deal with; the more supple replacements are now absorbing the road bumps. Or else it was gremlins.