Completed my suspension modifications this week and believe I've found a good formula that retains the qualities but addresses the compromises. One must really address your rear end geometry if you are going to get the front end correct. I wanted a more responsive and crisp ride so here is what I did.

I replaced all the bushings front and rear. While my car has only 37,000 miles, its 12 years old and the bushings, all of them should be replaced. Poly bushings are not recommended as they are not needed to achieve the desired effect.

For the front shocks I used Bilsteins. On the rear I went for heavy duty KY's. A heavy duty shock is needed on the rear if you want to accomplish what you want with the car's cornering.

While I had the front end dropped I replaced the lower control arms, a known weak point on these cars.

I wanted to replace the rear sway bar with a wider diameter but could not find an aftermarket part so I did the next best thing, installed up rates sway bar links front and rear to take the factory sway bars to their limits.

I added a new set of performance tires to finish the job off.

The transformation in the cars handling is nothing short of spectacular. She rides beautifully, Corners beautifully. At speed the car is responsive and crisp.

I recommend this formula to anyone with and X308 XJR car if you wish to achieve the car's handling limits while retaining the cars Jaguar qualities.

 

Sounds great Jeff!

When is the test drive?

I'll get my helmet

Stewart

 

Thanks Stewart. Mixing the shocks, Bilsteins front and HD KYBs in the rear plus the up rated sway bar links made a very large improvement. Of course, all the rubber bits should be changed with OEM. Regardless of miles, the car is almost 13 years old! I would have put a larger diameter sway bar on the rear but could not find an aftermarket part to do the job, hence the up rated links. Been for several rides since picking the car up Friday and "love it."

 

How much did this suspension project cost you excluding the new tires?

 

your car must have had some issues, I also have a 01 XJR (I'm the first owner) with about 35,000 miles and all my bushing are in great shape.
You mention a "known issue" with front lower control arm. never heard about it. What type of issue?
I fail to see how "up rate" sway bar link can "improve" on a sway bar. Sway bar ( or anti-roll ) are designed to resist body lean and the part that do that is the sway-bar, not the links that are on a vertical plane. At the most, urethane bushing will make the sway bar react sooner.
My experience with KYB shocks is that they are pretty harsh, specially on the rebound.
no trying to be critical but I have been racing cars for the past 20 years and know a things or 2 about suspension and handling.
It's also human nature to always feel an improvement after spending money.Lol

 

Have you seen these braces made by Ultra Racing. They bolt right on.

Jaguar XJ-8 (X-308) 4.0 (1997) Rear Lower Bar / Rear Member Brace - Ultra Racing Product Catalog

 

What exactly are they? How are they different from the stockers?

You don't mention alignment. Are the settings stock or tweaked? And to what values?

The nice thing about the X308 is that all of the expected adjustments are available unlike some other cars where they are fixed at the factory values and cannot be changed without the use of addon kits. Alignment can have a major effect on perceived handling. Setting alignment to personal preferences is often the cheapest suspension "upgrade". Especially if it is DIY.

 

I had a 2000 XJR that I bought, then sold a year ago, prior to this one, and it did not have the suspension wear that my 2001 had, The 2000 only had 9,600 miles when I bought it. The 2001, 35,000 miles. I buy these cars sight unseen and I was a little surprised when it was delivered. At speed it was unsteady. The front end plowed through corners. Under normal breaking conditions the car seemed to rock forward then back when it came to a complete stop (lower control arms). Part of the issue is I was comparing it to my XKR that has all the R Performance options including the up-rated suspension. Lets face it, the XJR is never going to track like the XKR. I just got back from a 100 mile drive and I'm impressed with the set up. The KYB rear shocks are a bit on the harsh side, but I like it. The Bilsteins on the front feel fine. Do you have any experience with performance exhaust systems for these cars? I'm looking at the one from AJ6 Engineering or Quick Silver (both made in the UK).

 

Here is the XJR, XKR and the XJS V12.

 

Powerhouse Automtive in the UK does a thicker/stiffer rear swaybar for the X308. Have a look on ebay.co.uk

 

I would wager that the X308/R is or could be in the same league:

X100:
Dimensions
Wheelbase 101.9 inches (2,590 mm)
Length 2005-06: 4,775 mm (188.0 in)
Width 2005–2006: 1,800 mm (70.9 in)
Height 1999–2006 XK8 Coupe: 1,283 mm (50.5 in)
XKR Coupe: 1,278 mm (50.3 in)

X308:
Dimensions
Wheelbase SWB: 112 in (2,800 mm)
Length SWB: 197 in (5,000 mm)
Width 69 in (1,800 mm)
Height SWB: 51 in (1,300 mm) (XJR ROW spec is lower)
Curb weight SWB: 3,968 lb (1,800 kg)

Any info on what the "upgraded links" actually are?

Alignment specs?

 

I assure you that the XJR can keep up with the XKR and beat it depending on the type of track. It's shorter wheelbase makes up the difference of the 100-150lbs of weight, same power, etc etc....

They are the same... i doubt you'll see the XKR beat out a similar XJR consistently.

UPDATE

Ok, just as I thought .... Found some stats, mind you that the 06(which is an 2007 in North America) XKR has 40-50 extra hp than a 03 XJR and a couple hundred pounds lighter:

Track XKR XJR
Vairano Handling Course 1:24.59 1:25.68
Autozeitung test track 1:43.10 1:48.90
Technical data

Engine 4200 245 bhp/tonne
Specs

Max speed 280 kph 250 kph
0 - 100 kph 4.9 s 5.3 s
0 - 100 mph 11.3 s 12.0 s
0 - 200 kph 16.7 s 20.2 s
1/4 mile 12.9 s 13.4 s
1/8 mile (est) 8.8 s @ 87 mph 9.0 s @ 86 mph
Power/weight ratio 233 bhp/tonne 245 bhp/tonne
Summary

Discipline XKR XJR
Track Performance 34 points 0 points
Straight line speed 219 points 205 points
Total 253 205



2003 XJR vs 2000 XKR:

Specs XJR XKR

Max speed 250 kph 250 kph
0 - 100 kph 5.3 s 5.4 s
0 - 100 mph 12.0 s 12.1 s
0 - 200 kph 20.2 s 20.6 s
1/4 mile 13.4 s 13.7 s
1/8 mile (est) 9.0 s @ 86 mph 9.1 s @ 86 mph
1/2 mile (est) 21.5 s @ 128 mph 21.6 s @ 127 mph
Power/weight ratio 245 bhp/tonne 226 bhp/tonne
Summary

Discipline XJR XKR
Track Performance 0 points 0 points
Straight line speed 205 points 201 points
Total 205 201


I ASSURE you that with a wider stance, 200-300 lbs lighter and some lightened unsprung weight in addition to AVOS Twin screw and light mods, there are going to be very few cars to beat it around a track. These cars are really fun to toy with i'm finding.

 

I have the Super Sport + Suspension Upgrade, Cross Drill Brembo Disks, 20 inch wheels and Adaptive Damping (CATS) on my XKR, all factory installed options. I have thought that the 2002 XJR 100 might keep up with the XKR due to it's suspension, break and wheel upgrades. Good track times can be as much about "stop" as they are "go." But don't know if the non 100th anniversary X308 XJR cars can match an XKR with all the R Performance options on it. I'm going to put them both through a slalom course in the spring when I'm done with the modifications to the XJR and see what happens.

 

Which Bilstein shocks did you use for the front? Comfort, Touring, HD, or Sport?

Any reason you did not use Bilstein HD shocks for the rear rather than KYB ?

You refer to upgraded rear sway bar links: where did you get them and how are they an upgrade over stock ?

Thanks!

Dan
2000 XJR in Oklahoma

 

I'm going to check with the shops who did my work. I took my car to Sports Car Tires in Wilmington, DE and they took it to Al and Jim's suspension shop also in Wilmington. Both of these shops have been in business for many years and understand and work on many of the higher end sports cars in this area. What I did is tell them what I was trying to achieve and took their recommendations. My goal for the car is to "retain the qualities and address the compromises." We had a good dialogue, test drove the car prior to doing the work and when the car was returned I got exactly what I was looking for. I'm not a DYI kind of guy but know where to find folks who will listen to me and give me what I'm looking for (for a price of course). Both my XJS V12 and XKR R Performance cars are 100 percent stock and original as they were build at the factory. I don't know why I feel compelled to modify the XJR. I think luc was right in an earlier post when he said my car must have had some issues when I purchased it. Anyway I'll find out exactly what parts the suspension shop put on the XJR to achieve the result and report back.

Next modification is the exhaust system, after I change out the secondary tensioners. I'm looking for folks with experience installing either the AJ6 Engineering or Quick Silver performance exhaust system. I think they are both good systems but an leaning toward the AJ6 system as I believe it will be quieter than the Quick Silver system. If I get a wild hair I may put the Quick Silver system on the XKR as the factory system is too restrictive.