Turning a luxury Saloon into a desirable Coupe

The Jaguar XJC is a two door Coupe version of Jaguar’s very successful XJ Series 2 saloons.  They were produced from 1974 to 1978 and only a relatively small number were built, especially the V12 powered versions, which makes them a very rare and collectible classic car today.

In today’s market it is rather difficult to locate an original Coupe in very good condition.  In fact finding any top condition Jaguar XJ Series 2, especially a V12, is quite a challenge.  Unfortunately many have found their way to the scrap yard thanks to neglectful owners and Jaguars major downfall “RUST”.  Many of the Coupes that come onto the market are in need of expensive repairs and rebuilds and others that seem sound are often not as good as they are represented.

Despite the fact that the Coupes are around fifty years old there are still some outstanding examples of XJC’s around and they continue to grow in popularity as conscientious owners lavish time and money on maintenance and restorations.

Production facts and figures
As can be seen from the production figures below, only 10,426 Coupes were built by Jaguar/Daimler UK for world distribution, compared to 116,652 XJ Series 2 Saloons.  The V12 powered cars are the rarest with the Daimler V12 being scarcest and most collectible of all.

Only 603 Jaguar XJC V12's were built in right hand drive and only 97 were sold new in Australia.  My XJC is one of the original 97 and only 39 are known to still exist!.  140 XJC 4.2’s were sold new in Australia.   Over the years a small number of used Coupes have also been privately imported into Australia.
World production figures for Jaguar XJC
Jaguar XJC 4.2 6,487
Daimler XJC 4.2 1,677
Jaguar XJC 5.3 1,855
Daimler XJC 5.3 407
Total   10,426

Annual production of Jaguar XJC V12
1974      11
1975    821
1976    663
1977    329
1978      31
Total    1,855

From XJ Saloon to XJ Coupe

The two door XJ Coupe was based on the short wheelbase version of the four door Jaguar XJ saloon.  The front and rear designs were left unchanged, even the front windscreen and rear window are the same, but from the side the difference is very obvious.  The first prototypes were built using short wheelbase series 1 XJ saloons and one of these prototype vehicles still exists and lives in Western Australia.

Jaguar used as many existing parts and panels as possible from the four door saloon to minimise development costs.  For example, the door shells were made by joining an extended door section to the end of the original saloon door (see photo right) to provide a 100mm (four inch) longer door rather than manufacture an entirely new door shell.  A large strengthening panel runs through the middle of the door and this plus the elaborate window operating mechanism results in rather heavy doors which required heavy duty hinges.  The XJC uses the stock sill panels from the short wheelbase saloon and if you look closely you can see the indentation where the original centre pillar was intended to be welded.

During development of the Coupe, Jaguar experienced a great deal of difficulty in sealing the side windows to the roof line and this delayed the release of the XJC for quite a while.  To overcome the sealing problems the engineers developed rather complex door and rear quarter window mechanisms.  The power windows had to raise and lower easily but still maintain enough pressure to keep the windows against their seals, even at high speed.  An additional objective was to have the windows completely disappear inside the panels to provide a windowless side presentation with the windows down.  This system required a large amount of development time but wind noise at high speed and poor weather sealing is still a common problem with the XJC today.

The Coupes were produced in both Jaguar and the more upmarket Daimler versions and they were all fitted with a vinyl roof.  Various theories have been put forward to explain the vinyl roof but the most common belief is that it was a design decision to enhance the appearance of the pillarless saloon.  Only a handful of special order XJC's left the factory without a vinyl roof but some owners have removed them over the years.

The interior is the same as the short wheelbase saloon except that the front seats fold forward to allow access to the rear seat and the seat belt anchor points were also moved.  Rear seat accommodation, leg and head room are much better than most two door Coupes and the large front doors make entry and exit much easier than the saloons.  The combination of leather trim and polished timber add a touch of old world charm to the interior, although the general design was a bit dated when it was built.

XJC door
Original XJ saloon doors were extended by 100mm (four inches) to suit the new XJ Coupe.
Side quarter windows
Clever mechanism to ensure quarter window glass pressed tight against the seals, even at high speed and disappeared completely into the quarter panel in the down position.

Unfortunately the 1970's were not a good period for corporate Jaguar (under Leyland control) and this was reflected on the production line where disgruntled workers showed little concern about quality control and Jaguar build quality suffered during this time.  If you take a close look at an original Series 2 Jag you may still notice many fixtures and fittings that could have been better finished and the paint and panel fit was often poor.

Advanced mechanicals

The XJC used the same advanced mechanical specifications as the saloon and the superb four wheel disc brakes (four pot callipers and ventilated rotors on the front), fully independent suspension and power assisted rack and pinion steering were very advanced for the time and provided the cars with a legendary smooth and quiet ride with exceptional handling and braking.  Even today the front and rear mechanical assemblies are still in demand by builders of performance cars, kit cars, hot rods and Cobra replicas etc.

The XJC could be ordered with either the legendary 4.2 litre, twin overhead cam six cylinder with 170 bhp (127kw) or the powerful but thirsty 5.3 litre V12 with 285 bhp (212kw).  The V12’s lightweight aluminium block and heads, sophisticated overhead camshafts and advanced fuel injection provided a powerful and unburstable engine that propelled the XJC to a top speed of 140 mph (225 kph).

Jaguar's V12 engine began with the E-Type

In the 1970's, as now, Jaguar's biggest export market was the USA.  By 1971 pressure was mounting for manufacturers to reduce the emissions from their engines.  Although the necessary reductions could have been achieved on the long serving XK six-cylinder engine that had been fitted to the E-Type since its introduction, this would have greatly reduced its performance.

So a new engine was needed that would meet the new American regulations but still deliver the 'punch in the back' that E-Type owners expected. The question was, what type of engine should it be?  Over the years Jaguar had built a reputation for engineering innovation and this was to be a significant factor in designing the new engine. When the six cylinder XK engine was first introduced in 1948, it was one of the few double overhead camshaft straight six engines available to the public.

The image of technical superiority was important to Jaguar.  A V8 configuration was considered but discarded as being too common, especially in the USA where Jaguar had a big market for the E-Type.  For the E-Type to retain its unique appeal, something out of the ordinary had to be developed.

The prestigious Ferrari and Lamborghini cars had created something of a mystique about V12's in both Europe and the USA, so the logical step was to consider a V12 configuration. There were several advantages to this type of power unit including the fact that a V12 is significantly smoother than a V8.  So the V12 became the preferred engine design for the revised E-Type and also the Jaguar saloon's.  In fact, Jaguar had been working on a V12 (quad overhead cam) for some years. It had been intended for the company's return to racing when fitted to the experimental XJ13 racing car, which never saw the track, and factory sponsored Jaguars were not to be seen on the race track till many years later.

Unfortunately, the engine that had been designed for racing proved to be too complex and expensive for a production engine, added to which the dual overhead cams per bank made it too big for the E-Type and saloons.  Nevertheless, it was this unit that was to provide the basis of the 5.3 litre V12 unit (single overhead cam per bank) that was eventually fitted to the new E-Type and then the Jaguar XJ saloons and two door coupe.

Renowned engine designers (including racing engines) Walter Hassan and Harry Mundy applied their magic and developed the production V12 with a lightweight alloy block and heads.  The narrow 60 degree V design enabled the twelve cylinder marvel to fit inside the narrow subframes of the E-Type.  A number of small single cylinder test engines were built to test cylinder head and combustion chamber designs. Remember that this was before the introduction of sophisticated computers and CAD drawing programs that are now used for such design exercises.

The tests resulted in the surfaces of the V12 aluminium heads being machined flat and the combustion chambers placed inside the piston crowns.  This design provided more efficient combustion, improved mid range power, helped to satisfy the emissions requirements (especially in the USA) and also made for easier (and cheaper) manufacture.

Industry leading electronic ignition, four Zenith Stromberg carburettors and a free flowing exhaust system completed the revolutionary new engine package from Jaguar.  This basic engine design was further developed over the following years and went on to power Jaguars for another twenty five years until it was finally retired in 1995 with a fuel injected, six litre capacity producing 313hp (233kw).
Early Prototype V12
The Jaguar Quad Overhead Cam V12 race engine underwent a great deal of development but was too complex to be a production engine.
Jag E-Type V12 engine
V12 E-Type Engine
The V12 Single Overhead Cam production engine as it first appeared in the 1971 E-Type Jaguar
V12 XJC Engine
By the time it was fitted to the XJC in 1975 the V12 was fuel injected