I would like to modify the suspension on my XJR to achieve a sportier ride and better handling. I just acquired my XJR 3 months ago and compared to my 2005 XKR, the XJR feels like it has the comfort suspension. I thought the XJR came with a sports suspension? I've searched for posts and am not finding anything that gives me exactly what I'm looking for.

The car came with Kumo all season tires and I plan to switch them out to P Zeros shortly. I've wondered if the springs are shot? With only 36k miles, the car has sat a lot prior to my purchasing it. Should I replace the shocks? The ones on the car now seem OK but is there something sportier that does not ruin the Jaguar ride. What about all the rubber parts on the suspension? Should I replace them with original equipment or polyurethane parts? My front end plows a little. The car also tramlines but I wonder if that is due to the Kumo tires and will go away when I put P Zeros on?

In summary, I want a sportier ride, not a harsh ride/ but a sportier ride and sportier handling with my XJR.

Thanks everyone.

All the best,

Jeff

 

Check out all of your bushings before going to new springs, I would imagine they might be perished and causing the soft ride.

 

Making your car any stiffer than it is will not definitively make it handle better. The new mustang cobra track times improved when they lightened their spring rates. For road racing with variable pavement, I would NOT recommend going stiffer. If you are ONLY going to autocross, then stiffer may improve your times.

Ideally you "want" your road race car to almost bottom out on the worst bump on the track. Some suspension travel is better at keeping the tires on the ground. Far too many people go stiffer/too stiff, and if they ever actually drive the car at 9/10ths or 10/10ths they find they bump slide in some corners and cars with "softer" springs/shocks stay on the correct line for a single apex. If your springs/shocks are too stiff, as I often see on tracks, then you may be getting bump/slides in the turns that require you to have to shoot for a 2nd apex on the same turn, which is a huge disadvantage.

Definitely swap to new stock bushings everywhere as they may be worn out.

I do not race my xjr, it is my daily driver. I am going to duct the base model brakes, adding ebc slotted and dimpled rotors, but I am sticking with the stock springs and shocks. I find it stiff enough. I have never bottomed out on a hard turn. I'm keeping the car at it's comfortable 4100 lbs. If you do race it, you area likely to start getting rattles here and there, which I find annoying.

My 2000 xjr is fast enough on street tires to surprise newer modified corvette drivers on off and on ramps at maximum g's, and if they do not know what they are doing I often pass them on the INSIDE of a 2 lane on ramp and they are helpless to catch up before we get to the freeway. Once we get to the freeway, of course these 700+ hp monsters fly by me, but by that time I have already backed off and proven my point.

 

The problem with the stock springs is ride height. They are too tall and allow too much body roll. A set of lowering springs will help handling just by lowering the CG. And 99% of the USDM cars came with the Supercharged Comfort spec springs, which are IMO too soft. A slight increase in spring rate will definitely improve the handling on our cars, as it will decrease roll and pitch, which are not as well controlled as I'd like to see. Note that we're not talking much of an increase here, maybe 10% stiffer, which is what the main aftermarket spring brands (Arden, Paramount Performance, Mina) seem to offer. I do believe any of these lowering springs will offer a nice increase in handling ability and a significantly sportier feel. The biggest thing the XJ needs is bigger swaybars, as they will reduce body roll without a significant increase in effective spring rate so ride quality is maintained, but no one seems to offer them. So the only easy way I see too increase the roll rate resistance is through higher spring rate. On shocks, the stock Bilsteins are VERY well damped, and can handle a slight increase in spring rate just fine, and as no one like Koni or anyone offers a sportier shock (Bilstein HD Sports are available, but insanely expensive), they are currently the best easy option. The best non-easy option is Bilstien will rebuild and revalve your current Sport shocks to be slightly stiffer, but it isn't cheap and requires a few weeks of downtime as they're being done. I feel like it could do with some slightly stiffer compression damping, so I may do this here in a little bit. The other piece of the puzzle is bushings. Most of the bushings in the front suspension are too soft to start with IMO, and they degrade surprisingly quickly. Powerhouse Automotive out of the UK offers polyurethane bushings for most of the critical spots in the front suspension which by all accounts really helps as well.

 

Ultra Racing 4 Point Front Lower Ladder Bar Brace 97 03 Jaguar XJ 8 X308 V8 | eBay

Ultra Racing 3 Point Rear Lower Tri Tie Bar Arm Brace 97 03 Jaguar XJ 8 X308 V8 | eBay

 

Standard bushes all the way, have tried polyflex/powerflex etc and they make a noise.

Proper asymmetric tires will help, they tram like a tram on symmetric tires.

Hunt down the "SuperSport" package springs, UK and Euro supplied R springs from Jaguar, I guess we like ours sporty over here

Genuine Jaguar Parts and Jaguar Accessories for Classic Jaguars from Jaguar Classic Parts UK

 

Yes, yes yes! Brace everything you can.

Here is "the family" track car. A different kind of cat. 1974 (re-titled to correct 1973) Pantera GT-4 converted to GT-5. WELL Over 500 RWHP, currently 2900 lbs, goal weight of 2500 lbs. Here are few photos of track and street set ups. This car is a beast and does see 10/10ths on the track. My XJR is just a daily driver. This is the toy. And no, it is not a kit. Windsor stroked to 408, wilwood superlight 4 piston brakes in all 4 corners. 15 x 10 and 15 x 14 slicks for the track. Every conceivable brace.

The biggest problem with lowering the ride height of the XJR (which will improve handling, of course) is that you will now hit all the parking berms and curbs with your front air dam. It is a bit of a practicality trade off there.

 

I had a Mercedes that was 4" off the ground and wasn't a problem parking or pulling into driveways unless you park by feel lol

Too Jags are far from a stiff structure, so anything that is out there has to help. My W124 was an ingot compared to the wet noodle the Jag is. By far the Jag is a faster car, but it can't touch the quality of the Merc that was 7 years older.









My car now

 

If you notice, the Poon-Terra (calling it what it is ) is also British Racing Green!

That is one pretty kitty you have there!

 

I noticed!

Thank you!!

 

Thanks everyone for the advice. Think my biggest problem is I compare the XJR ride to my XKR ride with all the R Performance options and suspension on it. There is no comparison between the two.

 

BadBenz94,I have the same car as yours, but changed a few things since purchase.before it was like exactly yours. sorry,my car is bit dirty

 

Beautiful car Vincent! Where'd you get the little lip spoiler for the rear decklid? I've been looking for something like that for quite a while, and that is exactly what I pictured in my head!

 

Painted Rear Trunk Boot Lip Spoiler for Jaguar XJ308 1997 2003 Sedan | eBay

 

How about a better picture of the boot lip?