XJ-SC and AJ6 Engine

October

The 1984 model year saw the XJ-S range expand with the introduction of the six-cylinder AJ6 engine on the 12th October 1983. The new power unit met Jaguar’s standards as a replacement for the old XK engine. The main advantages were that it was lighter in weight, and had better economy. The company invested heavily in a new engine for its growing model range, and committed £30 million to the project. The all-new engine was a 3590cc aluminium alloy unit. It had two overhead camshafts and 24 valves, and was only the third Jaguar engine to be introduced in the post-war period, following the XK series in 1948 and the V12 in 1971, both of which continued to power other models in Jaguars range. All three engines were produced at Jaguar’s Radford plant – the old Daimler factory – in Coventry.

In the 3.6-litre XJ-S, to go with the new AJ6 engine, a new Getrag 265 five-speed gearbox was introduced, so a manual option was available again since its deletion in 1979. 

To fit the new engine, the bonnet had to be re-profiled giving a slight power bulge to allow for the taller AJ6 engine, the V12 kept the flatter bonnet. Otherwise, there was very little change to the exterior except for a 3.6 litre badge on the boot, “S” badge on the radiator grille, Pepper pot alloy wheels, also known as perforated alloy wheels, Seat facings in leather, with Ambla trim elsewhere; the V12 had all-leather trim

Compared to the V12 models, the 3.6 litre version was £2000 cheaper and as a consequence, it attracted a wider sector of customers and introduced more people to the brand. The 3.6 was seen as a more sporting car, especially as it was fitted with a manual gearbox; performance was not far behind the V12, yet fuel economy was significantly better.

For the XJ-S HE, there were four major refinements introduced: Wash/wipe system that cleared the headlamps of dirt and spray, this improved the visibility for the driver in poor weather conditions, A sophisticated trip computer, this provided information on average speed, average fuel consumption, the amount of fuel used and a digital clock.

In addition to the 3.6 litre Coupé, Jaguar produced a Cabriolet (XJ-SC) version. The XJ-SC benefited from the top of the range equipment level equal to that of the V12, including the starfish alloy wheels and full leather trim. Designed as a two-seater, the Cabriolet offered a number of interior storage areas, behind the front seats there were twin lockable storage boxes above which was a luggage platform fitted with a forward retaining rail. For some, the introduction of the Cabriolet version meant a return to the open air motoring not seen since the end of production of the E-type in 1974. The Cabriolet was produced against specific customer orders only, and Jaguar made use of the specialist body-building and coach trimming skills of Park Sheet Metal Ltd in Coventry as well as Aston Martin Tickford at Bedworth.

In brief, the Cabriolet started life as a standard XJ-S body at Castle Bromwich but the roof and rear header panel were left off. Due to the design, the XJ-SC required additional work which meant it going to Park Sheet Metal for the fitting of rear panels and bodyshell strengthening. After that, the bodies were transferred back to the Castle Bromwich site to be painted. Following painting, the bodies were returned yet again to Coventry where the final assembly was done at Browns Lane. The Tickford facility at Bedworth then installed the roof, composed of a folding rear hood with the alternative of a half-hardtop, and removable targa-type panels for the front. After completion of this, the cars were returned to Browns Lane for the final inspection, road test and audit. A more detailed account of the production methods follows below.

Within the Castle Bromwich facility at each sub-assembly point jigs were used to assemble the panels. This was done to the tolerances pre-determined by the design. Larger jigs were used on the main assembly line to ensure the tolerances were maintained throughout the entire build process. Following the body-in-white process, the exterior shell was drilled to allow fitment of exterior trim. Prior to the bodies being shipped to Park Sheet Metal, they were inspected and oiled before being stored in a computer-controlled facility.

When the bodies were received by Park Sheet Metal, the work undertaken included the removal of the roof and the distinctive buttresses, the reinforcement of the under body and boot area, the re-styling of the rear panels, fitment of the front header panel and installation of the twin roll bars which were totally enclosed within the contoured panels. The bodies were then returned to the Castle Bromwich plant for rust protection and painting.

The bodies were then sent to Browns Lane where they joined the other XJ-S models on the pre-mount, mount and trim tracks. The pre-mount track was responsible for the installation of the wiring harness, sound proofing, brake pipes, air conditioning and windows. The mount track took care of the front axle, rear axle, engine, transmission, exhaust and wheels. Once on the trim track, the interior features were fitted, including wood veneer for the fascia and door inserts as well as the Connolly leather trim.

After the hood, roof panels and hardtop had been fitted by Tickford at Bedworth, the completed car finally returned to Browns Lane where checks were made to ensure the car complied with the legislative requirements of the final destination. Prior to despatch, the cars were valeted and the remaining exterior trim was fitted followed by a final quality audit.

The two interlocking targa roof panels were trimmed in black fabric to look like a soft top. The panels were lightweight, tipping the scales at only 12 lbs (5.4kg) between them. There was a storage envelope for the panels in the boot. A folding rear hood in black fabric was supplied as standard, together with the alternative rear half-hardtop. The hardtop incorporated a heated rear window which was direct-glazed to the panel to reduce wind noise and improve rigidity. The folding hood was closed using a simple “lift and push” action to lock onto the centre bar. When it was lowered, the hood stowed away above the rear deck line, folding away beneath a tailored padded cover. The roof panels and the hood were trimmed with a nylon headlining. The black colour theme was continued to include the roof panels, the centre bar, header rail, cant rails and the “B” posts.

Designed as a two-seater, the Cabriolet offered a number of interior storage areas, behind the front seats there were twin lockable storage boxes above which was a luggage platform fitted with a forward retaining rail.

Park Sheet Metals is a small business in Coventry that specialises in modifications and limited body construction. Formed in 1947, and during the 1950s started making body panels for Daimler including the later DS420 which carried on until the end of the DS420 Limousine production. The cabriolet started life as a standard XJ-S body at Castle Bromwich but the roof and rear header panel were left off. Due to the design, the XJ-SC required additional work which meant it going to Park Sheet Metal for the fitting of rear panels and bodyshell strengthening. After that, the bodies were transferred back to the Castle Bromwich site to be painted.

TWR

1983 was to be the year that changed the dynamics of the relationship between Jaguar and TWR with Jaguar officially announcing their endorsement. The livery of the 1983 XJ-S changed from the previously used black body to white and dark green. The newly designed body structure was viewed by BMW people as controversial and even illegal, the cooling duct was a structure that was introduced to aid the rear axle oil coolers. TWR ignored the comments being made and kept the unsightly ducts for the entire season.

March

TWR’s season started at Monza, unfortunately, Calderari’s debut race for the team ended in disappointment when retired with engine failure, which was blamed on poor quality fuel being used. It looked like his misfortune would spread to the other car when a securing pin on the bonnet came out, and the bonnet was flapping. The pit crew frantically sought some sticking tape to secure the bonnet and three hours later, they found they’d only lost first place by three-half seconds to finish second.

April

Vallelunga saw TWR Racing on the grid in second and third place. Walkinshaw led the pack when he crashed into the barrier, after one of his wheels sheared off at the bolts. Despite damaging his hand on the steering wheel, Walkinshaw managed to get the car back to the pits. Calderari took over once the wheel had been replaced and the slight body damage repaired. Despite his best efforts, Calderari was hit from behind and spun out of the race, into the undergrowth. When Dieudonne in the second car came in for a pit stop, Walkinshaw took his place to bring this car into third place but unfortunately, he couldn’t claim the championship points because he’d switched cars.

May

Donnington saw the TWR team rack up another win in May. The team worked tactically together, Walkinshaw took the decision to use the softer Dunlop tyres which were not wholly recommended in the rain but it meant that he could leave the rest behind. In the meantime, Fitzpatrick used the more conventional harder compound tyres, to hold back the pack in order for Walkinshaw to get away. Brundle had an exceptional debut race, although he’d practiced in the XJ-S he hadn’t actually raced one before. Rain was falling but Brundle had the right tyres for the job, he worked his way up the field and crossed the finish line in first place, 20 seconds ahead of the next car.

May was a busy month for the TWR team, Walkinshaw and Nicholson scored their first points when they romped home in first place at Pergusa in Italy. Unfortunately, Calderari had a poor race when he retired with loss of oil pressure. At Mugello one week later, Walkinshaw and Fitzpatrick had to be content with a third place, after an additional pit stop for fuel was required due to their car running rich. Calderari and Nicholson were forced to retire with a broken pulley tensioner which unfortunately was a recurring problem.

June

The TWR team was at Brno where Walkinshaw finished comfortably in first place, putting him one point ahead of his nearest rival, Quester. Calderari and Dieudonne were looking to finish in second place when they were overtaken by four BMWs, after they suffered a rear-end breakage which almost made their car unsteerable. Both cars succeeded at Zeltweg with another impressive one-two win. Walkinshaw and Brundle came in first even after there was a protest about Brundle’s commitment eligibility as Brundle had moved from Formula 1.

July

The race at the Nürburgring did not go TWR’s way, both cars failed to finish. Walkinshaw’s car suffered an ignition fault which resulted in his cockpit filling up with smoke, the second car retired due to a clutch failure. Matters improved slightly at Salzburg in July, when Walkinshaw and Nicholson came first. Their car went through two extremely fast pit stops which drew applause from the watching crowd. They took the decision to race just one car at Salzburg, leaving the second in the Kidlington workshop to rebuild it for the forthcoming race at Spa.

August

The last three rounds were not going to be as successful for TWR, Win Percy joined the team at Spa and followed Walkinshaw in the opening laps. Walkinshaw was leading when he suffered a puncture and Percy had to come into the pits when he was overcome by the heat. Calderari took over and he, Percy and Brundle raced through the night, when Brundle experienced a massive engine failure and was forced to pull out of the race. Walkinshaw and Dieudonne continued to race but unfortunately had to retire due to a differential failure, after having lost time while the prop shaft was being fixed.

September

September saw them back on home turf at Silverstone, the rain started and Dieudonne had to come straight into the pits following the warm-up lap due to a belt tensioner failure, which cost him two laps. Dunlop couldn’t produce a tyre that suited the conditions, and although Nicholson initially led it didn’t last for long, as he spun out at the chicane and into the fence. Walkinshaw took over from Dieudonne and despite his attempts to move up the field, he only managed to finish in ninth place.

October 

If Walkinshaw could finish fourth in the last race he’d be the champion. Percy led the race until he was sidelined by clutch failure due to a gearbox problem. Brundle was experiencing problems with the gearshift change which lost him a couple of laps, so between Brundle and Walkinshaw they could only manage an eighth place. The 1983 championship ended with Jaguar finishing second with five victories, while in the non-championship race at Hockenheim Calderari had finished first.

November

The 1984 season loomed and the TWR XJ-S cockpit underwent a number of changes that were primarily for comfort and convenience, rather than for technical advancement. The wheel size increased to 17in with a 13in rim which was permitted by the regulations. 

The colour scheme remained white and green, however, the dominant colour was now green instead of the white as on previous models, and featured two main sponsors – Jaguar Cars and Motul Oil (although Motul was taking a back-seat to the manufacturer in advertising space).

For the 1984 season, Tom Walkinshaw was joined in partnership by Hans Heyer who had previously raced with the BMW team. Win Percy became a regular driver for the Jaguar team and was partnered with Chuck Nicholson.