I've done some searches but I've only come back with some limited info so I thought I'd start something myself where everybody could impart there experiences, knowledge etc.

My Renault suspension is custom made by a company called Leda Suspension, which is now owned by the same people who own Harvey Bailey Engineering (HBE). HBE specialise in handling enhancements for prestige cars. HBE offer some Anti-Roll Bars for S1/2/3 XJs as well as Bilstein dampers.

HBE say that the Anti-Roll Bar kit retains 95% of ride comfort?....

I think this thread needs to be categorised by what you want from the car. Some will want ultimate handling and others will want to keep the ride quality untouched and everybody else fits somewhere inbetween.

From what I have gathered so far the handling mods that make a difference are:

1. Series 1 Upper Wishbones with Series 2/3 Lower Wishbones and Uprights.

2. Uprated front (up to 1" diameter) Anti Roll Bar.

3. Uprated rear (up to 7/8" diameter) Anti-Roll Bar.

4. Replacement Dampers (Koni, Bilstein, Gaz, KYB, Boge, Leda or Spax).

What have people got at the moment?

 

I can comment on shocks, the suspension in my '84 is totally original:
Bilstein, KYB, and Koni will give a harsh ride to the XJ. The original XJ shocks were Girling, which are softer shocks. The XJ handles fine with soft shocks and looking at pictures of racing XJ cars and even older Jaguar, leaning is always present, so hard shocks will not eliminate lean. In fact, leaning appears to be desirable in racing Jaguar. My '84 Series 3 still has the 4 original Girling in the rear. I replaced the fronts with Boge and they are a total dissapointment. Fortunately I never throw away old parts and I still have the 1984 Girlings which I plan to re-install.

For better handling that makes the car "stick" in hard cornering, I decided for better tires instead: I installed Dunlop XP Sport 235/60/15, really wide tires that preserve the comfortable ride but the car will not slide in hard cornering. I would not use Pirelli or Michelin; Pirelli are terrible in wet conditions, and Michelin are way too harsh. Dunlop was the answer for me. Best tires I ever had, not noisy either.

 

Yes, mostly true, so long as both wheels (on either end) hit the same bump at exactly the same time :-)






Define "ultimate handling" :-)

For some, "good handling" is simply and only defined by less body roll/flatter cornering. For others it also includes steering response, maximum adhesion to the road, reduction of understeer (or in some cases, oversteer).






Unless your goal is simply the flattest possible cornering stance, this is too big, IMHO. I had (among others) a rear 7/8" bar on my XJS. It was stiff enough to cause skittering across road imperfections while cornering and also created a situation where major oversteer came in quite suddenly when driving hard thru a corner




Nothing at the moment, as my XJR is corners well enough for me without modifications. However, my experience with many cars over the years is that soft OEM springs, high qualty shocks, and uprated/added antiroll bars are a good combination for real world use....with the caveat that one CAN go too far with the anti-roll bars.

And, of course, tires :-). Tire design can make a huge difference not only in road adhesion but steering feel and response.

On our old Jags good rack bushings are a must....as the originals are soft and almost always totally worn out.

Cheers
DD

 

It's not so much that lean is desirable. More like making the suspesnion so stiff that lean is eliminated is *undesirable*.






Do your recall which specific Pirelli and Michelin tires you were unhappy with? Each company makes a very wide variety of tires with different characteristics to match different purposes....so we can't go by brand name alone.

For example, you are very happy with the Dunlop XP Sport....but you may be very unhappy with some other offering from Dunlop.

Cheers
DD

 

Does the xjs and xjr have different a/roll bars to the xj series 1/2/3?.

This could be a very useful thread.

 

Here's my experience so far:

My XJ6 suspension is stock except for poly steering bushings and a 1" front sway bar with poly mounts and end link bushings. I installed them before I ever drove the car. I can say that those two modifications alone did not ruin anything for me. My opinion is that there is nothing harsh about the car. I am looking forward to more modifications that stiffen up the suspension, including 17x8" wheels and tires. With that being said, my daily driver has stock 18" wheels so your harsh may be different than my harsh.

Also, I know handling is highly subjective, so here's what I use as a barometer: That guy (any guy) that's telling you about his ride - look at the tires he's running. If he's still on those skinny 15" tires with the mile-high sidewalls, that tells you something about his preferences. He probably enjoys a soft, compliant ride. His idea of "corner carving" or good handling is probably a lot different that the guy who has 17" or 18" wheels and low profile tires on his XJ or XJS. Like you said - preferences vary widely on this - you need to adjust the feedback to that person's preferences in order to get useful information.

 

Yes, different bars.


Cheers
DD

 

I did the same on my Ser III. A worthwhile reduction on body lean giving a more secure feel thru the corners. Understeer was naturally increased but this wasn't eveident unless you were driving very hard thru the corners.






Very true.

Most Jag drivers are fairly conservative and a "refreshingly brisk drive thru the mountains" is about as serious as they get.

Others view every curving freeway on-ramp as a do-or-die challenge and strive to get through it a bit faster every day on their drive home from the office :-).

As for the latter one must honestly evaluate their skill level and tolerance for terror. If a 4200 pound Jag gets away from you.....well....um.....it isn't especially easy reeling it back in :-)


Cheers
DD

 

I suppose I would consider handling as improvements to steering response, like turn in, and getting a bit more grip from the same set of tyres while cornering. I also think that it encompasses the general responsiveness of the car on the limit.

As a general rule of thumb, the difference between front and rear roll stiffness will change the cars general handling in one of two ways.

By stiffening up the front roll stiffness (or softening the rear or a combo) will make the want to understeer more.

By softening up the front roll stiffness (or hardening the rear or a combo) will make the car want to oversteer more.

There are limits to both...

Another rule of thumb is reducing the unsprung weight will improve the handling and responsiveness of the car but, on the XJ I don't there is too much that can be done other than fitting lightweight alloy wheels (22" chrome spinners are not lightweight) and replacing the brake calipers with aftermarket alloy versions? The XJ's rear brake set-up already favours this, by moving the rear brake discs and calipers inboard, they are no longer part of the unsprung weight!

What bushing material (stiffness), and where it's fitted, will also have a dramatic effect on response but sometimes at the expense of ride quality.

Good damping is the hallmark of a quality sports car and what brand to use seems to be the biggest talking point for these cars. Adjustable dampers may be the key to finding the balance people are looking for.

Gaz and Leda in the UK will be able to produce some adjustable dampers (if they don't already) but, they will be a bit more expensive than non-adjustable types.

 

It would be interesting to know what parts can be substituted from other model jags (e,g, xjs) as an improvement and how to do it.
I'm guessing that the a/r bars form an xjs would be and improvement and should be a direct fit or is there more work to be done?

Are the springs and shocks on the sport setup for the xjs or xjr a useful upgrade?

The later sports steering rack form the xjs would be good as well but I think the lower shaft may need to be changed as the tower is taller. I don't know how this would be done or how easy it would be.

Also useful would be some info on what later wheels would be suitable and maximum width or tyre size before problems such as wheel rubbing occurs.

It would save a lot of trial and error on my part at least!

 

not me, I like it fast, and I like it sticky like contact cement. Actually, cornering is one of my best abilities as a driver, I trained in an MG-B starting in 1969, in a local racetrack at night, then moved to a Volvo 1800-E in 1973, talk about a fast car.

my '65 S type corners as good if not a lot better than the XJ. Think of it as a MK-2 with XJ IRS, which is exactly what it is. A lot more fun to drive because it makes a lot more exhaust noise than the XJ and you can hear the carbs breathing the gasoline and you can smell that classic car combustion! Some people never grow up and I have nothing to prove. Remember those 1960's Italian movies where the S type driver was escaping from the crooks in the Peugeot? That's me.

 

The front bar from an XJS is a direct bolt-in on a Ser I-II-III XJ6/12.

The standard XJS front bar is the same size as the XJ12 front bar (at least the Ser III V12 front bar), 3/4" or something like that

The Sport Package XJS V12 front bar is a bit bigger....maybe 7/8" ? Can't quite remember

The XJS rear bar can be installed on a Ser I-II-III XJ6/12. You'll need to drill anchor holes in the body. You'll also need the bar-to-body brackets, drop links, and the rear radius arm with the drop link mounting tabs....although these would be easy to fabricate and weld in place.

The early XJS rear bar is smallish, maybe only 1/2' or so, but it makes quite a big difference. Later rear bars were slightly larger as I recall.

All XJSs until 1980-ish had the rear bar, at which point is was eliminated. It reappeared and disappeared again 2-3 times in the late 80s-early 90s depending on spec and market.




XJS springs may physically fit but I'm not sure about ride height issues




I've seen a Ser III with 17x8 wheels from a 1995-97 XJR/6 using 255/45 tires. The owner reports no problems with fit. I've also seen Ser IIIs with 15x7 and 16x7 wheels, using 235/60 and 225/60, respectively, tires with no fit problems

Cheers
DD

 

One of the "fast" cars I drove recently was a 2009 Porsche 911 4S. If a 1973 Volvo is like contact cement, what does that make the 2009 Porsche? You can't even fairly compare the two - they're worlds apart, as is our perspective!

 

There's someone with a black XJ6 SIII on the boards that has 17x8" XK Revolver wheels on his car - not sure which tires though. He said they fit fine, but required a 1/4" spacer to get the center caps on.

 

careful with that Porsche, they are treacherous cars, their rear engine weight gives you a false sense of security in cornering. What I meant about the 1800-E was that at cruising speeds it had an overdrive almost like a 6th speed, very very high geared, that made the car cut through, pulled you back on the seat and got up to 130 mph very fast, it was my first experience with a supercar.

I never took it to 160mph because my knees started shaking at 130.

 

Years ago I owned both an XJS and a Mustang 5.0. The Mustang was undeniably faster thru all my favorite twisty roads....all the ones that were reasonably smooth, that is :-). The cornering surprisingly good on that car but it simply couldn't handle rough roads on its ox cart suspension. Fun car, though, for what it was.

My MGs cornered well, too....again, "for what they were". Elderly design even in the era they were buing built. Nimble and responsive but an utterly unsophisticated suspension. In an MG you always feel as though you're going faster than you are so it adds a bit of thrill.....and you think the car is handling better than it really is. But, again, still lots of fun. I'd love to own another.

Nowdays part of my job is to drive many different cars, old and new, including exotics. Suspension systems have evolved so much, and are so good, I think I'd need access to a test track and a lot more courage to identify which corners "best". I'd be way beyond my comfort zone and skill level.

Even ordinary family sedans do amazingly well. The bar has been significantly raised on all aspects of performance in the last couple decades.

Jaguar has long been praised for great suspensions, and rightfully so. Jaguar gets a good blend of comfort versus cornering/handling.....but if a compromise is needed Jaguar always leans (tee hee hee) to the comfort side of the equation.

Ramble switch "off".

Cheers
DD

 

no way to improve the XJ, that car was Sir William Lyons "world supercar", and he had it engineered to be the best it could be. If you want a tire melting dragster, buy the new Camaro, it's awesome but way too big.

and if anybody here knows how to make cars run on water, please let me know.

 

Right, best it could be....within various design and price parameters, intended use and market, etc. Every design has compromises. Jaguar did better with compromises than many others, but still, a compromise is a compromise. Various aspects CAN be improved on.



Heck, with today's technology you can have tire melting, comfort, cornering, good fuel economy, etc all in one package




Me too !

Cheers
DD

 

Actually most (all?) of that treacherousness in the old 911s was designed out years ago. Of course, like most performance cars these days, there is so much power that the car can be treacherous in that respect. You can't just jump in one and drive it at the limit or anywhere close.

Well, I can't, at least.




That must've been a seriously modified 1800E ! In stock trim they only have about 120 horsepower or so.

Cheers
DD

 

the problem Doug, is that I am old skool, I don't like sensors, or nitrogen-filled tires, or run-flat tires, or anti-lock brakes, and more sensors which sense the sensors, and EGRs and Carbon Canisters, none of that.

give me an old carburetted car that spits fire through the exhaust pipe, and I'm happy.

everything is so "sensor-based" now-a-days that it makes me sick. And when something goes wrong, no way to fix anything. My three cars are old. I'm happy. They can be fixed without parting the car for a "bad computer". You know exactly what I'm talking about. (the '95 XJ). Nobody could fix it so they decided to sell it in parts. They're still selling it in parts.