When looking for my Jag I first drove the XJ8. I was blown away by the ability of the suspension to soak up bumps and imperfections, but it wasn’t floaty like American sedans. My XJR is pretty good at this and still carves the corners like most modern sports sedans. In my opinion the R has a much better compromise of ride vs. cornering than BMW perhaps.

Question is, what are the main differences between the standard wheelbase XJR and XJ8 in terms of suspension. I know that the XJ8 has “comfort” shocks and springs and a smaller roll bar and the XJR has CATS and stiffer springs/roll bars. Any other differences? Would it be possible to put the softer XJ8 springs into my CATS equipped XJR? Would it make a difference or would the whole suspension have to be changed? Although I like the flat cornering and power of the R, I fell in love with the standard comfort of the XJ8.

Also…. How much do the wheels and tires have an impact on ride quality?

 

To the best of my knowledge the spring rate is higher on the R as well as being fractionally shorter than the 8. As you said the shocks are stiffer as well as the larger sway bar. The 18" 40 series are going to be considerably stiffer than the 16" on the 8. I would not recommend putting anything different on the R as it would ruin the whole experience. If you really like the manners of the NA 8, then get one and drive both for the unique experience that they both offer.

 

You do have a point. X308's are cheap enough now to almost let me have another one. Heh. It's too bad this version on CATS couldn't do a wider range of settings.

 

More than you'd probably expect!

I bought my 1999 XJ8 with 17 Inch alloys.
Loved the smooth ride feeling but couldn't get used to the look.
(It was a set of these horrible lookin' "Celtic" wheels.)

So I changed to 18 Inch Penta alloys off a XJR.
The whole car looks so much better now.
But comfortwise I regret the change (sometimes).

David

 

I did the same thing with my Vanden Plas. I went from 16" factory rims to XJR penta rims with 245/45/18 tires instead of 255 width XJRs usually have.

I think the car is much better comfortwise and the steering is heavier (a good thing) and feels more precise. The 16" rims made the car feel soft and wobbly. The 18" rims make the car feel more solid and sporty while still being very smooth. I think with the Vanden Plas (Maybe has diff suspension than the XJ8) feels and looks way better than the standard 16". I have never regretted the change. My car feels like it should have been like this from the factory.

I have much better grip. The only problem is I have tramlining which I didnt have with the 16" rims.

 

I had to mount 255/40 18 tires otherwise it would have been illegal.
(Regulations are very strict over here.)

Tramlining (cool phrase BTW) is also one issue...

 

Tramlining is due to tyres, these cars are super fussy about the boots they wear. Any good quality Asymmetric tyres on the front (might as well fit all 4) will cure it whatever rim size you're running.
Pirelli even developed a tyre for them, the Asymmetrico - I used Michelin PilotSport 2's, but they wear too quickly, so now on Bridgestone Potenza, both are asyms, no tramlining, trust me, been there, done that with Dunlop sp sports, a £1000 mistake.

 

Have you tried the asymmetric Contiental Contiextreme Contact tires? I'm wondering if my tramlining is due to my tires or worn suspension.

 

now then....worn suspension..... symptoms? I'm going on my experience of two tread designs altering the way the car tracks along the road, the asyms deffo sorted the wandering I got with the Dunlops.
Bushes on the front end do wear. They're relatively easy to replace and cheap. A full set of tyres aren't.
What mileage B? did it do it with the smaller rim size? any clunks? play in the lower shock mounts (grab the lower part of the front shock with the wheels turned so you can grab it, and try and pull it to and fro')? Sway bar bushes? I guess spending a few dollars on new bushes and trying each (both sides) a step at a time will probably sort it at some point. I highly doubt wheel bearings, but check, jack each side and grab the tyre and rock it to see if there's any play....its a case of checking each thing that can introduce play.

 

I hope we arent hijacking the OP thread!

I have 96k miles on my car. I didnt have any tramlining before I switched to the 18" wheels back in '06 and about 15k miles ago. I have clunks and crashing over bumps. I have a worn engine mount. I had my bearings checked. They are ok. My upper shock mounts are visibly worn. At 96k miles, my sway bar bushings are prob gone. Since I don't have a lift or even a ramp, I have to depend on my $100 a her Jag mechanic. Since I dont have uneven tire wear and rarely drive on the highway, I decided to live with it for now.. What are the symptoms of worn sway bar bushings?

For the OP question, IIRC, the XJ8 actually dont have a rear sway bar at all. The 16" rims isolated my car a bit more from small road imperfections and large pot holes didnt crash through as much as they do with my 18" wheels (maybe increased wheel weight plays a role). My car felt more Cadillac like (also had more numb and lighter steering) whereas now it feels a bit more BMW like. The 16" wheels on my LWB car had pretty bad understeer at the limit.

 

Speaking of worn suspension... Thought I would ask, my front upper shock mount bushing is crumbling away. Any way to replace that with a new orange one? I've seen on other sites the kit for the XJ8 only replacing those with plastic inserts, not rubber. Any other options for me besides the whole mount for big $$$ ??

 

When I was looking for my 350 series car I focused on the XJR because I knew it would be easier to sell after I had put mucho miles on her. That's still true but boy you pay a price on a long trip with those 19" wheels, preformance tires and preformance shocks. It not horrible, mind you, it's just not what you sign on for with an XJ.

Anyway, like you I started thinking of ways to soften up the ride, such as comfort shocks, diffferent wheel/tire combinations, sway bars, etc. Short of replacing the Summer Hi Perf. tires, the options are much limited by cost considerations. Shocks at +$1200 a corner, wheels/tires at way upwards of $2000 per set quickly lead me to conclude that "if it's such a big deal I might as well trade the car for one that meets my needs".

So, you get right down to it that ain't a going to happen. I like the car too much to trade it off. The stance of an R and the insane accelaration atone for a lot of shortcomings.

 

thinkpad, check out the xk8/r subforum, I am not sure if the mounts are the same (much of the suspension is though) but we have had a member replace the upper mount 'rubber' bushings for a poly, it was simply a replacement kit.