Jaguar Model Guides : The XJS







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Jaguar
Model Guides : The XJS

by Pascal Gademer,
South Florida Jaguar Club




posted 2/14/05




Line of XJS at the 2001 JCNA Challenge
Championship in Franklin Tn

With so many pristine late model XJS still seen on the
road every day, it's hard to believe that Jaguar longest running model
is just about to turn thirty. In North America, the XJS largest market,
this milestone which will be celebrated at the 2005
JCNA Challenge Championship
, in Braselton Ga between September
21st and 25th.

Flashback to 1974: sales of the once popular E-type
are declining rapidly despite the introduction of the all new V12 engine
three years earlier and as the last E rolls off the line in Coventry,
Jaguar engineers are hard at work working on a replacement. Finally, in
September 1975, the new jaguar sports car is presented to the world at
the Frankfurt auto show and... surprise! Even though its mechanical roots
can be found in the series 3 E-type with the silky smooth V12 and Jaguar's
superior rear independent suspension, everything else has more or less
been thrown out of the window.

Even the name signals a break from Jaguar's sports car
past; the new two door isn't called the F-type as expected but instead
carries an XJ badge, just like the saloon. Good-bye sports car, hello
grand tourer. And adding insult to injury, the XJS is only available as
a Coupe, no more convertible: after 40 years of producing the world's
best looking open cars, Jaguar succumbed to safety regulations and would
no longer offer a ragtop until the mid 80s. Original reception by the
press and car enthusiasts was barely lukewarm, something very unusual
for the Coventry marque whose designs over the preceding 40 years were
usually met with jaw dropping looks of admiration.

The XJS is really the last Jaguar of the Lyons era as
Jaguar's founder was still at the helm in Coventry when work started on
the E-type replacement. It's also the last Jaguar influenced by legendary
aerodynamist Malcolm Sayer, whose mathematical formulas helped shape the
D-type, E-type and XJ13 prototype; sadly, he died in 1970 before work
was completed. The rear end of the car, with its rear window, buttresses,
large tail lights and thick dark bumpers, was like nothing ever seen on
a Jaguar.

As Jaguar buyers demanded more features and luxury,
especially in the US, the XJS was equipped with power windows, power locks,
climate control, improved noise and heat insulation and full instrumentation.
It also had to deal with increased safety regulations, once again from
across the pond, with 5mph bumpers, thicker doors, relocated fuel tank,
fuel pump inertial cut out switch and more. Despite the added luxury,
the XJS sported a wood less, dark interior trim in stark contrast with
the hot selling XJ saloon's luxurious cabin. The instrument panel was
very 1970ish with space age inspired drum gauges for the engine vital
sighs flanked by a pair of primary instruments (tach and speed). Not what
Jaguar drivers were used to...

Mechanically, the heart of the XJS was the V12 engine.
Although not new after four years in the E-type and three in the XJ12
saloon, its turbine like smoothness and seemingly endless torque quickly
became the XJS selling point. The 5.3 litre, 60 degree angle, 9:1 compression
ratio V12 developped 285hp at 5500rpm and over 300 lb./ft of torque at
3500rpm. In contrast to the simple carburetors used on the E-type, this
V12 was fed with electronic injection from Bosch/Lucas giving it its smooth
running characteristics. Nothing new in the transmission department where
European drivers had a choice of a four speed manual or the Borg Warner
three speed automatic. No such luck for US drivers who could only get
the slush box... In either case, final gearing was a low 3.07.

Suspension was conventional for a Jaguar with the now
proven independent rear suspension in its subframe assembly with inboard
brakes (2 piston calipers and solid rotors). Up front, the geometry was
similar to the E-type's (except for springs replacing torsion bars) with
anti dive geometry, an uprated roll bar. Front brakes used 4 piston calipers
with vented rotors and new Kent alloy wheels with specifically designed
Dunlops rounded up the package offering handling and ride qualities typical
of a Jaguar : firm enough for some serious driving but comfortable.



Click for
more pictures :

1990 US Coupe "Classic": front
view
, rear view , side

1989 US Coupe - side
view
- rear view

(owned
by Barry Moss, South Florida JC)


Trans Am legend Bob Tullius and one of his Group
44 XJS

Direct competition for the XJS were the Mercedes 450SLC,
Maseratti Indy, Lamborghiny Espada, Ferrari 365GTB or Aston DB6, ranging
respectively from 20% to 90% more expensive... Despite all its mechanical
qualities and competitive price, soaring gas prices following the seventies
fuel shortages and volatile economic conditions took their toll on the
XJS; its first years were the most difficult for Jaguar, with sales not
reaching the levels expected or even needed to keep it in production.
From a high of 4000 in 1977, sales slumped to just over 1000 in 1980.
Little was changed over these first five years except for the introduction
in 1977 of an improved transmission, the GM 400, replacing both the venerable
Borg Warner and the four speed manual. In 1980, a new Bosch/Lucas digital
electronic injection system brought in a little more power but caused
fuel economy, or lack of, to get even worst dipping into single digits
under spirited driving conditions. Despite being the only V12 engined
car available on the US market, lack of demand brought the XJS to the
verge of extinction. Success on American race tracks didn't help boosting
sales either despite Bob Tullius' Group 44 team winning both driver and
constructor Trans Am championship in 1978.

HE to the rescue

1980 saw the arrival of John Egan at the helm of Jaguar
facing a critical situation after years of slumping sales and declining
quality during the dark British Leyland years. Egan saw the XJS potential
and commissioned work by an independent Swiss engineer, Michael May, who
designed a new revolutionary head for the thirsty V12. Despite using a
high compression ratio (12.5 : 1), his "fireball" combustion
chamber design prevented detonation even with leaner mixtures; the result
is not only more power and torque but reduced fuel usage by as much as
20%.

Launched in 1981, the XJS HE (for High Efficiency) literally
gave the XJS a new lease on life. In addition to the improved engine,
the interior was redesigned with a new veneered dash (burr elm) and simplified
instrumentation. Outside, new five spoke Starfish alloy wheels, twin coachlines,
revised bumpers and mirrors gave the XJS a new updated look. In addition
to these changes, Jaguar's new boss committed to improving quality with
a new slogan : The Legend Grows. 1982 saw a sharp increase in sales with
some 3000 XJS delivered.

While the V12 engine was a symbol of power and smoothness,
the venerable inline six XK engine was the work horse powering the majority
of XJ saloons. With its roots dating back to the 1940s, it was time for
Jaguar engineers to come up with a replacement : the AJ6. In typical Jaguar
tradition, the new engine would first be used in a sports car and in 1983
Jaguar launched the AJ6 powered 3.6 liter XJS offering prospective buyers
a more economical alternative to the high end V12 XJS although it would
not be available in the US. With dual overhead cams and four valves per
cylinder, the 3.6 Litre engine delivered 221 hp and offered good performance
helping boost sales of the XJS. The 3.6 litre XJS gained a bonnet bulge
to clear the camshaft cover.

Topless is back!

Also in 1983, and after a nine year absence, open top
motoring was revived by Jaguar with the introduction of the XJS Cabriolet.
First available only with the AJ6 engine, the XJS Cabriolet was a compromise
to bring back a topless car to the market without a complete redesign.
Starting with a standard bodyshell, the roof was removed and cant rails
added along with a tubular steel reinforced Targa centerbar. Fixed quarter
windows remained while the transmission tunnel was stiffened and a ladder
frame bracing added under the rear suspension. The result was a body shell
actually stiffer than the later full convertible. A pair of fiberglass
Targa panel closed the space of the driver and passenger while a manually
folded half top enclosed the space behind the front seats, which included
a carpet luggage area with lockable boxes. As XJS sales rebounded, the
Cabriolet became available with the V12 HE and quickly outsold the 3.6
liter variant. Altogether, 5000 cabriolet (a majority of them V12 with
3800) would be build until replaced by a full convertible in 1988.



XJS
Cabriolet : Closed
- Open


(Jack Williams, South Florida
Jaguar Club)


H&E Convertible
- Top Down

(Bill Streitenberger, JOC Los
Angeles)


1990 XJS Convetible with "Classic"badge

Only 100 made: 1993 XJR-S
(Phyllis & LesChysholm, Suncoast
JC)


1992
convertible (facelift)


1996 Convertible (owned by
Jo-Ann Pruett,JC North Florida,

note:
"optional" Florida Panther presented by C.A.R.E. )



Between 1983 and 1988, the XJS remained for the most
part unchanged until an updated 3 speed automatic appeared in the 12 cylinder
model along with a new engine management system. Antilock brakes appeared
both in the six and twelve cylinder versions along with an optional sports
suspension package and interior upgrades including power seats.

By 1986, US customer demands for a true convertible
prompted Jaguar to commission Ohio coachbuilder Hess & Eisenhardt
to build convertibles based on coupes. Over the next 20 months, some 2100
cars would be shipped to Cincinnati where the roof would be removed, formed
steel members added to the bodyshell and an electric convertible top fitted.
The top was not padded, allowing it to fold deeper in the body than the
top would on the cabriolet or upcoming Jaguar build convertible. In march
1988 at the Geneva Auto Show, Jaguar presented its first true convertible
since the end of the E-type in 1974 with production beginning in September
as an 89 model and available in all market. The new convertible featured
a padded top with headliner yielding a taller profile when folded. Other
modifications for 1989 included a new steering wheel, multispoke alloy
wheels, redesigned seats and new burl walnut trim.

During the 1980s, Jaguar worked closely with Tom Walkinshaw
Racing to develop the XJS into a winning race car in the FIA World Sports
Car Championship. Increased power for the V12, weight reduction, larger
AP brakes were part of the recipe to take the fight to BMW along with
meticulous preparation. it didn't take long for Tom Walkinshaw to get
results with wins in 1982 at Brno, Austria, Nurburgring, Zolder and most
importantly on Jaguar home soil at Silverstone.

To celebrate the 1987 Championship and the 1988 Le Mans
victory of a V12 power XJR race car, Jaguar introduced a limited edition
XJR-S V12 coupe in 1989. Only 100 of the European market only cars were
built, all Tungsten colored, featuring TWR ground effect package, special
wheels and special interior. North American customers would have to wait
until 1993 for their own XJR-S with either Signal Red or Jet Black paint
and available in Convetible or Coupe. Again only 100 would be built, with
special body kit, wheels and interior. This would be the first appearance
of a 6 litre V12, developping 318hp thanks to a new Zytec engine management,
mated to a GM 400 Turbo automatic transmission and limited slip differential.
Note that this 6 litre engine was a stroked version of the 5.3, unlike
the the standard model 6 litre soon to appear in the XJS and XJ12.

Final facelift

1991 would see the final major cosmetic update to the
XJS with what is known as the facelift model launched as a 1992 model.
Little is changed mechanically but the big news in the US is the availability
of the AJ6 engine although now enlarged to 4 litre and mated to a four
speed automatic. Outside, the slightly softer lines were only the tip
of the iceberg as the bodyshell was now build from far fewer panels than
the earlier version with additional rust proofing treatment. While the
front end was for the most part unchanged, it is the rear which underwent
the most changes with revised quarter windows, a new rear window and all
new tail lights. Inside, the instrument panel was all new, loosing the
drum styled engine gauges replaced by conventional dials flanking the
two primary instruments, identical to the XJ40 panel. Extra veneer in
the instrument cluster added a touch of luxury along with a new steering
wheel and center console. V12 car received the same power bulge on the
bonnet as the AJ6 models and US market XJS were now equipped with one
piece Euro style Carello headlights. In Europe, the original one piece
Cibie were also replaced with a Carello, although different from the US
spec'd version.

In 1994, a 6 litre version of the V12, diiferent from
the 6 litre used a few month earlier in the limited edition XJR-S, replaced
the 5.3 litre unit, along with a new four speed GM400. New body colored
bumper replaced the smaller chrome and rubber version and the V12 model
gained a boot lid spoiler. Inside, dual airbags were added and the convertible
received back seats making it a 2+2.

1995 would mark the last major engine upgrade in the
XJS line with the arrival of the 237hp AJ16 engine although not available
with a 5 speed manual as a new electronically controlled ZF 4 speed automatic
became the only transmission available. Modified engine management netted
the V12 another 23 hp to 301. This would be the last year for the coupe,
at least in the US, and XJS production came to an end in 1996.

Ironically for a car which received a less than warm
welcome when introduced, it would become Jaguar longest running model
remaining in production for 20 years and 7 months during which over 115
000 units were built.



V12
or
Inline 6 ?

If the stock V12 isn't
enough how about adding twin superchargers ? 600+hp under the
bonnet of this highly modified XJS:

Engine - Front
- Rear

(owner Bradley Smith,
read
more here
)

Buying an XJS

Without a doubt, the XJS is one of the most popular Jaguar ever made
and while it may not have the appeal of the legendary E-type it is an
excellent choice for someone who wants to enjoy Jaguar ownership at a
reasonable cost; and who wouldn't!

Needless to say, with such a long run and model variations, XJS can be
found from very cheap, as in needing plenty of work, to excellent condition.
As with any "special" car (it's still a little early to call
the XJS a classic - no hate mail please...) buying the best you can afford
instead of the cheapest possible pays off. Maintenance history is important
to make sure an XJS has received the care it needed, especially for the
V12.

As a hobby or week end car, there is really no reason to stay away from
an early coupe especially if the price is right and if you don't mind
a trip to the woodless plastic age of the 70s. The V12 is without a doubt
one of the very best engine ever build by Jaguar or by any builder for
that matter. It is a rugged and reliable engine capable of high mileage
with very little problems. However, it doesn't like to be overheated so
keeping the cooling system in top shape is important. Any evidence that
a prospective V12 XJS maybe running hot is cause for concern and engine
condition should be checked thorougly by doing a compression check. Even
if the engine appears to be running well, rebuilding a V12 is an expensive
job ($8000 to $10 000); a compression test prior to purchase is cheap
insurance...

At the other end of the spectrum, the later XJS can make a very good
daily driver with decent fuel economy in the case of the AJ6 / AJ16 powered
versions. Needless to say, the V12 is anything but economical although
when driven sensibly it won't be worst than most of the SUVs seen on the
roads today. While the AJ6 and AJ16 engines may not have won Le Mans,
they are just as reliable as the V12 and easier to work on. Maintenance
on the V12 is more costly than on a 6 cylinder car, not only because there
are twice as many plugs, wires, injectors, etc... but because with such
a big engine access is limited; this is the price to pay for the glamorous
V12 badge.

Like any Jaguar, condition of the body is extremely important when buying
an XJS. Rust is a problem and can be very costly to fix; beware of recently
painted cars as that shiny new paint can hide poor repairs. Facelift models
(92-96) were build from fewer body panels and received improved rustproofing.

If you are looking for an open car, it maybe a little hard to decide
between the Cabriolet, the H&E convertible or the later convertibles.
Despite its Targa bar and fixed rear windows, the Cabriolet certainly
has its charms starting the various configurations one can choose: fully
open, rear convertible open or close, each Targa panel on or off. US buyers
face an other decision when it comes to the "true" convertible
between the H&E with its unpadded top but lower profile when open
or the Jaguar built version with the more luxurious padded top but sticking
out when folded down.

-
XJS Timeline -

Sept.
10, 1975
: XJS is launched

1977 : GM400 replaces Borg Warner 12 transmission

1980: new Lucas/Bosh digital EFI

1981: introduction of the HE V12 with revised cylinder
heads, Jetronics fuel injection, higher rear ratio,

revised interior with burl elm veneer on dash, door trim, new
switch gears and steering wheel (from XJ6),

new chrome mirrors on both doors,

revised bumpers and new Starfish Alloy wheels

1983 : 3.6L AJ16 engine introduced (except in the US),
Cabriolet model

1986 : Hess & Eisenhardt XJS Convertible (US only)

1987 : powerseats

1988 : introduction of the XJS convertible

antilock brakes, revised interior, optional sports suspension.

1989 : Le Mans XJR-S model (Europe only). New Marelli ignition
system (except XJR-S)

1990 : XJS Rouge Coupe (US only)

1991 : Classic Collection XJS

May 1991 : introduction of facelift model with revised
body, tail lights and rear windows, XJ40 based instrument pack,
single piece Euro style headlights on US model

1992 : 4.0 AJ16 engine, new 5 speed Getrag manual gearbox
and new dual mode automatic

May 1993 : new larger plastic bumpers, V12 enlarged to
6 litres, 4th gear overdrive equipped GM400 transmission, outboard
rear brakes. New limited edition XJR-S available in the US

1994 : revised AJ16 engine with sequential fuel injection,
new seats

1995 : Celebration model

1996 : XJS replaced by XK8, end of the line as well for
Jaguar's legendary V12 replaced by the new AJ-V8





1989 XJS Coupe (Barry Moss, South Florida Jaguar Club)

Driving an XJS

Torque is really the key word when driving a V12, this is no 7000rpm
buz machine, and 80% of peak torque is available from as low as 2000rpm.
On the road, downshifts are only needed in tight passing situations. The
3 speed automatic used until 194 is adequate but for pure driving enjoyment
a manual gear box is best. Unfortunately, manual XJS were never exported
to the US but it is possible to upgrade an automatic XJS to a 5 speed
manual, a costly upgrade but the best way to improve performance.

Handling and ride qualities have always been a key part of the Jaguar
driving experience with just the right balance of comfort and handling.
The XJS is no exception although models with sports suspensions, wider
wheels and lower profile tires will have a stiffer ride. Brakes are adequate
for normal use but the XJS is a heavy car and long downhill drives may
require special care.

Over the years, the interior of the XJS has been constantly improved
and refined with the later models setting standards in comfort and refinement.
Even the early XJS are far more "civilized" than the E-type
it replaced with far better sound and heat insulation, improved climate
control, etc...

Maintaining an XJS

The XJS, whether V12 or AJ6/AJ16 powered, is not the maintenance nightmare
some claim it is. It is a complex luxury car with an exotic V12 engine
which will require a little more attention than your basic Chevy. Speaking
of which, sadly a number of XJS have been "lumped" with V8 over
the years as ignorant mechanics convinced owners that the original V12
was the source of their problems. Needless to say, these cars aren't worth
much.

As mentioned earlier, the Jaguar V12 is a reliable engine capable of
producing far more power than the 300hp or so it delivers in the XJS however
there are a few issues related to auxiliary systems, mostly cooling and
ignition. The cooling system is adequate but needs to be maintained; any
overheating can result in severe damage lke dropped valve seats, blown
head gaskets, etc... Many owners have chosen to upgrade the radiator to
single pass alloy unit.

The V12 is a big engine installed in a fairly small engine bay resulting
in a lot of heat trapped especially after shutdown. Not shutting down
the car immediately after a hard run helps reducing chances of heat damage
to ignition and injection components. Until 1989, Jaguar used Lucas electronic
ignition, first the same OPUS system used in the E-type and after 1982
a Constant Energy Ignition system. Despite the common jokes related to
Lucas, both systems are reliable but shared a common problem with the
distributor centrifugal advance having a history of seizing resulting
in power loss and overheating. In 1989, Jaguar switched to a Marelli electronic
system using crank sensors to adjust timing (no more frozen centrigugal
advance) and a single distributor with a separate coil for each bank of
the V12. Because each bank uses a separate coil, it's possible for one
bank to fail while the other will still be running; the engine will obviously
lack power but still run smoothly. If the driver doesn't stop the car
right away, the fuel injection keeps sending fuel to the dead bank and
the unburned fuel sets the catalytic converter on fire... Periodic inspection
and replacement of the cap and rotor is key to avoiding this problem although
there are a number of modifications which can also eliminate the risk.
Regular inspection of fuel injection hoses is equally important, there
is nothing like fuel spiling over a hot engine to ruin your day!

Servicing the rear brakes on earlier XJS is harder because of the inboard
brake design until 1993. Rear brakes were mounted near the differential
to reduce unsprung weight and improve handling but are harder to service,
requiring dropping the rear suspension to change rotors and calipers.
Routine service like bleeding or pad changes is no problem though.

The AJ6 and AJ16 engines are easier to maintain, having more space around
in the engine bay, and are equally well designed as the V12. One potential
problem lies with the head gaskets which can fail sometimes under 100k
miles. Repairs are easy and even well within the capabilities of any good
DIYer.

Regardless of age or engine, parts availability is still excellent with
a number of specialists carrying virtually any part needed. In some case,
good used parts can also be found resulting in substantial savings. Choosing
the right shop for service is absolutely critical and official Jaguar
dealerships are no longer the best choice to service or repair an XJS;
now almost 10 years out of productions, training for dealers technician
focus on the new generation of V6 and V8 engines and fewer of them are
familiar with the V12. Finding an independent specialist with Jaguar experience
is key to enjoying an XJS; someone who knows the car and its engine inside
out. For those who can do at least some of their own maintenance, there
is one must have / must read resource that no XJS owner should be without
: The XJS Book by Kirby Palm. Written by an XJS enthusiasts, this 700+
pages book is in part a compilation of owners posts on www.jag-lovers.org;
best of all it is free! Visit the Jag Lovers website to download it. Local
clubs can also be a good source of support or reference, visit www.jcna.com/clubs
for club directory in the US.

 



Four generation of Jaguars sports cars : XK120, E-type, XJS and XKR in
the background.

 


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