Albert, I got ya. Just reading your description of those roads gave me a pit in my stomach...lol.

Last weekend I drove a stretch of safer although also narrow roads that twist and turn around the outskirts of Lake Livingston, TX. I had my wife with me so I didn't want her to throw up, but I didn't feel that experience at all. What XK's did you have?

One other thing about the confidence, I fully agree with that. I will say most reviews say the XKR-S tires felt greasy and the car was overall very slick. That will certainly hinder confidence. The XKR-S GT not only has suspension upgrades, it has R-comp tires. It makes a good difference as you know.

 

There is no argument there. Even testers who did not like the handling of the car on the track had stated that the real road driving experiences (ie. less than near maximum efforts) for the XKR(S) were excellent.

However, please do note that now that as soon as the GT raised the spring rates 60+ percent, the tester remarks about jiggly steering, instead of how you described your car:

"...steering wheel is absolutely free of any vibrations and it is a pure pleasure to drive..."

That is how my XK steering was on open road, free of vibrations and pleasant to drive. On my XJL which has such jiggling and vibration my strong suspicion is that Jaguar has used springs that are too stiff for the dampers. The dampers work fine dampening out the mid to larger sized road dents and imperfections but, go into oscillation when encountering pavements that have no real imperfections but, normal traction-inducing road texture. The motion frequency of that texture is so high that the dampers can not react to them sufficiently.

Edit - Matt, you said above: "The XKR-S GT not only has suspension upgrades, it has R-comp tires. It makes a good difference as you know."

Oh, I didn't catch that. Now, that makes a world of difference. At least 3 seconds/lap over regular street tires and far more sure-footed adhesion to the surface. As long as you do not install them for street driving... I'd done that and they almost killed me in a canyon race. They need to be brought up to racing temperatures and that, I found nearly impossible on regular roads, even without any traffic. If they are cold, they are more slippery than a set of K-Mart tires.

Also, to answer your question: I had an '05XK and an '08XK.

Albert

 

Bingo my EXACT thoughts on my car as well, the damping especially the rebound is WAY to soft.

 

I don't know why Jaguar makes a car that can go 180+ depending on trim but the dampers on road undulations at higher speeds do not match the spring rates.

 

Interesting debate, but axr6 did misunderstand the article (sorry, Albert):

I've emphasised the key word in red. What they are saying is: the R-S GT steering isn't like a race car, it is not super-precise & jiggly, but it is communicative.

I've not really experienced the steering on a standard XKR 'under pressure'. The steering on mine is the same as the Dynamic Pack and R-S, and it is sufficiently direct for my taste when I'm pressing on.

 

Also keep in mind other than Sebring, most tracks are pretty smooth compared to public roads some of these issues may not be noticed during track events.

 

I can tell you that, at 180 mph, I experienced no undamped oscillations even on sections of autobahn that were not 100% smooth. The 75 does have 30% stiffer springs than a standard XKR, though.

 

That is what "harmonic" frequencies will do to you. My XJL is generally behaving OK up to 65MPH and above 85MPH. Too bad that the speed limits in the US are 65-70 MPH and to avoid the vibration I have to risk a major speeding fine or the anger of motorist that I am holding up.

Albert

 

It's ok, when you drive an XJ, people will assume you are 90 years old anyway so it's perfectly fine to putt along at 55!

(My apologies if you are indeed 90 years old!)

 

No, I am an OLD dog that still have some teeth left but, not quite that old. Still young enough to have been beating all young competitors in my self designed and built racing kayak ever since I built it, over 5 years and counting. (of course, it is the KAYAK and not me that is so fast. They just don't know, yet, where the hidden motor is.

I heard that Jaguar was making a "successful" effort moving the XJL away from its old people image. Hope that it is working. I am actually much more nervous about driving under 65 on the CA freeways than going over 85. I never got a ticket for going too fast on a freeway (and, oh boy, I did) but, you can really upset some people going too slow around here

Albert

 

I think this suspension is the big difference if you drive "enthusiastically", stiffer springs and Dampers are a must. The stock XKR suspension is great for normal spirited driving but when pushed exhibits some "sketchy" nervous tendencies.

Ngarara - How do you feel your suspension handles cornering and how is the body roll? I'm still trying to decide if I'm going to take the plunge on XKR-S GT sway bars to complete the suspension package. I have to move quickly as there are only a few left in the world.

 

Drove my car a lot last Saturday, trying to see if I could find any real issue with the steering in my XKR-S. I am very happy to report that for a such a heavy car, I still remain impressed with the steering accuracy during aggressive driving on the streets, even when actively trying to find fault. I think the wheel is obviously more numb than it could be, but turn in is very crisp and feels quick in my car. And of course, I am extremely impressed with the overall ride quality for such a powerful monster of a GT. I am sure the steering and suspension can be improved such as MaximA is doing, but for me I am very happy with the XKR-S for how I use the car.

I know there are quite a few differences between the '08XK and '12+ XKR-S, especially in the steering and suspension. I suspect therein we see our differing perspectives.

Albert, I will say if you are ever in Houston I will throw you the keys and we can take her for a spin.

 

Matt

Be careful with offers... the last time I guy handed me his keys and asked me to show him what his Vette was capable of... was left in a state of near nervous breakdown One third into our canyon test drive he screamed for me to abandon my demo, thinking that I was going too ****** fast. I told him to hold on for the real show, as I was still holding back, warming the car up...ha...ha...ha...

I am very happy that you enjoy the car and, as I said before, the XK(R) is a superb GT for most everyday use. It is, when taken to near the limits where it begins to leave you wishing for more. At this stage of my life I could be very happy to own one, again, perhaps stepping up to the XKR or the S. As of now, when my XJL lease expires, my choice could well be between that and the F-type coupe. I'll decide after seeing, driving the F-type.

All the best to you,

Albert

 

The 75, Dynamic Pack & R-S have re-tuned Adaptive Dynamics damper-control software, increased spring and damper rates (front springs 28% stiffer, rear springs 32%) and lower ride height (10mm). They also have different front and revised rear suspension uprights that increase camber stiffness by 30%.

Subjectively, the car has little body-roll, though it doesn't feel excessively stiff. Here are a couple of 'Ring shots; the first is halfway through Brünnchen (uphill, cresting, slightly reverse-cambered right):



And the second is the exit from the Small Carrousel (rough, sweeping, heavily-cambered left):



So, some roll, but not really noticeable from the driver's seat - things are a little exaggerated in the second image due to acceleration squat (you really boot it out of that corner).

If you're buying the rest of the GT package, and have the money, I'd say: get the full set. Mr. Pook wouldn't have put the sway bars in there if they weren't necessary.

 

Thank you for the detailed images and explanation, I'm currently going with the Spires Coilovers as these guys spend some serious time on the track with Jags and BMWs. They are building me F-Type dampers with coilovers ~30% stiffer than the RS for my XKR. If the GT package part by part is extremely expensive and I might as well buy the GT. I do regret not getting the speed pack but from what I have read the Coilovers will make me happy. It just always concerns me that such a heavy car has such small sway bars but I'm going to see how it handles before dumping 1200+ into a sway bar.

How fast are you going in the second picture? The right rear is under a heavy load but the camber looks dead on.

I believe Spires modified a XR75 like yours let me check and if so I'll post the article for you.

From Spires:
The (F-Type)dampers are subtly different in rebound and compression forces (circa 5% stiffer at higher forces and 5% softer in the lower forces). This will help with traction on slower bends and pull away, but give more ultimate control when driving quickly.
It's more the increased spring rate which will give the most benefit to the handling performance. The front spring goes up to 100N/mm from 79N/mm and the rear increases to 120N/mm from 95N/mm.

 

I appears to me that the car could definitely use larger sway bars. Too much body roll in those pictures will slow the transitions.

Albert

 

I can agree but I wonder what the speed is exciting that cambered turn. Coming out of a cambered turn like that onto a flat surface will cause a lot of weight transfer. Hence the large sway bar LOL I answered my own question, and its the transitions that have bothered me most. Oh well overpriced sway bar here I come.

 

Hard to say - 70? Judge for yourself at 10:05 on here:


I wish I'd positioned my Road Angel so that the speed was visible; there are a few places on the lap that I'd like to know my speed.

 

Transitions are fine, at least at my speeds - watch the video, and you'll see that through the twists from 7:18 onwards (Wippermann, Eschbach & Brünnchen). There was never any sensation of it 'lurching' from one attitude to the other. Those images represent some of the points of greatest stress on the circuit. Coming out of the Small Carrousel the camber change is particularly abrupt - the concrete is banked, the tarmac isn't, so the car tends to hop a bit, as this guy will attest:

 

LOL That only thing that will fox that is about 200lbs of sandbags.

I've never been on that exact track but I know coming out of banking abruptly as in that turn upsets are cars balance very quickly.