Jaguar XJ Series 3

Introduction

Jaguar's of the 1970's were never perfect. Like all others, there were design and manufacturing weaknesses. They had problems and failures. But compared with their international rivals, Jaguar's XJ saloons were unrivalled. Bob Knight was the chief architect of the original XJ chassis, and by the time the Series III was released, he had been promoted to Jaguar's Managing Director.

The short wheelbase saloon and coupé had been dropped during the final years of the Series II XJ. The introduction of the Series III model also saw the option of a sunroof and cruise control for the first time on an XJ model. The 1979 UK model range included the Jaguar XJ6 3.4 & 4.2, XJ12 5.3, Daimler Sovereign 4.2 & Double-Six 5.3 and Daimler Vanden Plas 4.2 & Double-Six Vanden Plas 5.3.

Naturally the chassis remained as before - so what improvements had been made to make the Series III worthy of carrying the XJ tradition into the 1980's? Critics of the Series II pointed out the automatic remained a relic, the windscreen wiper movements were old fashioned and a litte weird, there was no seat height adjustment and the central locking system didn't open the boot. Some bemoaned the lack of rear headroom, and on the outside - leastwise at first appearances, not a whole lot had changed since the original.

But that in itself was one of the beauties of the Jaguar. Unlike most other manufacturers (and particularly the Japanese), Jaguar did not fall for the panic to make major facelifts every four years in a foolish Gadarene rush to pay tribute to the false god fashion. The XJ body may have been just shy of 11 years old by the time the Series III was readied for production, but it remained both superbly handsome and instantly recognisable.

But to those who dared look a little closer, there were in fact a lot of changes, mostly details. The Series 3 XJ incorporated a subtle redesign by Pininfarina, which included of course a new tail end treatment, and the rear roof line was extended further back to make a sharper corner with more upright back glass (thus raising headroom inside). The sidequarter window had a kinked rear frame, the side windows were deeper and the bumper was more substantial. There were even changes made to the door handle and wheel trims.

Fixing The Rear Headroom Problem

The height of the body remained the same, but in order to give more headroom at the back, the roof line was raised slightly as it neared the rear, reducing the inclination of the back window and giving a slight sharpening to the XJ's appearance. In front the windscreen pillars were more heavily raked (three inches more, measured at the roof end). The roof width was reduced slightly, giving more tumblehome of the sides (from roof to waist). The windows were deeper and the front quarter light was deleted to give the car something nearer the enviable cleanness of looks of the lamented two-door coupe.

All models had laminated windscreens, and these were thermal-glued inplace for the first time on a Jaguar, which gave a claimed improvement in bodyshell stiffness. An Inalfa electric sunroof became an option. Its operating rack ran down the inside of the rear quarter pillars and across the front side of the squab panel; the drive motor was on the other side of the panel to cut down noise intrusion.

Below the waist, the door handles were modified to be flush fitting and there were new bumpers which made a tidier job for Jaguar of producing cars to suit Europe and America. European cars had a black injection moulded centre to give a little protection from tactile parkers, but for America this section was replaced by a more projecting one to meet US 5 mph protection regulations - this being achieved via Menasco telescoping struts, the reinforcing beam backing the bumper for the US bound cars being changed to an aluminium alloy extrusion, which saved a total of 351b front and rear.

The front bumpers contained the indicators and the rear bumpers carried the fog guard lamps (except on US cars) inside, instead of bracketed below as on earlier XJ's. In front the Daimler grille remained unchanged, but the Jaguar one was slightly different, with vertical bars and a centre rib instead of the previous grid. Sidelamps, separate on the Series II, were combined with the outer headlamp. There were bigger area back lamps, and the number plate lamp and boot handle are altered. Twin door mirrors were fitted, manual for UK cars and electric for Europe (although UK cars could be optioned with electric ones). Cars fitted with the standard wheels had different wheeltrims.

The Big News For The Series III was Lucas-Bosch L-Jetronic Electronic Fuel Injection

To our mind, the most exciting improvement of the Series III XJ was the adoption of Lucas-Bosch L-Jetronic electronic fuel injection fitted to the 4.2 litre 6L engine, which was combined with a considerably higher compression ratio - raised to 8.7 instead of the previously modest 7.8-to-1. There were slightly larger inlet valves -1 7/8in. instead of 1 3/4in. - and earlier inlet opening (22deg before top dead centre instead of 17deg). The higher compression happened because of the use of the old E-type "9-to-1" ratio pistons and the extra space taken by the bigger valves and in spite of a thicker gasket. The result was a noticeable increase in maximum power, which went up by 19 per cent from 172 bhp (DIN) at 4,700 rpm to 205 at 5,000.

Maximum torque went up from 222 to a considerable 236 Ib ft but occurred at a higher speed - 3,750 instead of 3,000 rpm. Jaguar claimed that the overall efficiency had improved noticeably, so that 1000, 2000, 3000, and up to 4000 Engine RPM economy was appreciably better. This was not simply an improvement in day-to-day overall consumption due to better cold start economy obtained automatically thanks to the stricter control exercised by a good injection system, but applied apparently throughout the regime.

On over-run, the fuel supply to the injectors was cut off completely as a further economy and of course in the interests of better emissions; it cut in again at 1,200 tprn. Other gains included less maintenance (Jaguar-Daimler franchise holders will be equipped to deal with the system even though it is different from the 12-cylinder car's Lucas-Bosch D-Jetronic set-up. There was less engine noise thanks to the elimination of the hot air flap for the air cleaner of carburettor cars, which produced some intake roar.

No doubt some Jag enthusiasts will write in to Unique Cars and Parts to tell us that a fuel injectied 4.2 XJ had existed for a year prior to the release of the Series III - and they would be right; the car began production in this form for North America, meeting Federal emission standards with the addition of Bosch Lambda feedback control catalyst but without using an air pump or exhaust gas recirculation. In this shape it had an 8.1 compression ratio for running on 91 octane low-lead fuel and developed 177 bhp at 4,750 rpm.

The 3.4 continued for Europe only with a pair of SUs, and the V12 remained unchanged. Jaguar were going to offer the Rover SD1 77mm overdrive five-speed gearbox in place of the previous Jaguar four-speed and separate electric Laycock de Normanville overdriveon the Series II, but it only became available as the manual option on 4.2 and 3.4 models. The delay was (we believe) due to noise problems, acceptable in the quiet Rover, but not in the extraordinarily quiet Jaguar. As fitted, the 77mm box for the XJ had modifications which included a stronger layshaft, bigger bearings, and a needle roller bearing instead of a plain one for reverse - these modifications applying to Rovers as well.

Reversing 40 Miles Up The M1

According to an interview conducted with Harry Munday, who was Jaguar's engineering director at the time of the Series III XJ, the needle roller reverse had already been adopted for police Rovers "for reversing 40 miles up the M1. Most regrettably, it was held that too few manual gearbox 12-cylinder customers exist for there to be any possibility of putting Harry's 84mm (the dimension of the shaft centres) overdrive five-speed into production".

Very similar to the 77 mm - which it antedates - it had the right ratios and a superb gearchange and, of course, more than enough strength for the 5.3. Failure to produce it meant the end of the manual box XJ-S after the last of the four-speed gearbox stock ran out - which makes them very rare today. The automatic boxes remained the same - Borg Warner's Model 65 for the six-cylinder cars and GM's "Turbo-Hydramatic" for the twelves - although the Model 66 superseded the Model 65 and brought with it a long wanted improvement in selector change quality.

Inside there were a host of detail changes inside the Series III XJs, especially in equipment. Cruise control was made available for automatic 4.2 and 5.3 models, and fitted as standard on American export cars. Jaguar used the Automotive Engineering Econocruise model, which worked in the usual way - using the "set" button to select the chosen constant cruising speed or, by keeping the button pressed, accelerate to a higher cruise speed. There was a "resume" button for returning to the selected speed after having braked - which released the cruise control - the speed being remembered electronically. The "set" button was on the left hand steering column stalk, while "resume" and the on/off switch are on the centre console.

Optional on all but the Daimler Vanden Plas was a headlamp wash /wipe system that used miniature wipers as opposed to high pressure water jets: They worked on the flat-glassed outer main beam lamps only, actuated by the screen wash control and fed from a much larger reservoir - nearly 12½ pints instead of three - placed under the nearside wing. The feed was arranged so that the screen wash ran out first, leaving 1½ pints for the headlamps; this way round, the driver was reminded of the need to refill.

The old-fashioned wiper action on the XJ Series II was replaced with a more conventional one which parked automatically; intermittent wipe with a fixed six-second interval was provided, as well as the previous flick-wipe. There was also an electric delay circuit incorporated in the interior lamp circuit - giving occupants an extra 10 to 15 seconds of light after shutting doors in which to find ignition key and seat belts. Another delay circuit was used as on Mercedes and some other cars to prevent the rear window heater being left on for more than around 15 minutes; you could of course re-set it for another 15 minutes if necessary.

All Series III XJs for Britain came equipped with radio / stereo cassette players as standard, using the Philips AC 460 AM mono radio combination or all but Daimler Vanden Plas cars which had the AC 860 FM stereo radio. Four speakers were provided, one in each door. The other electrical change was the adoption of powered cushion tilt adjustment as an option for the driver's seat only on all but VDP cars which had it on both front seats. It was not proper a height control - the arrangement moved the back of the cushion through an arc of nearly two inches, pivoting about the front, with control via a rocker switch on one corner of the seat base. Lumbar support in front could be varied by up to 1½in., by turning a knob at the inside of each seat.

Door mirrors with manual interior control were standard on both sides, except on VDP and US specification cars which offered electric ones, optional on the rest. The optional electric sunroof mentioned earlier had an interesting detail found necessary in development. When open, in spite of a wind deflector, it suffered from the pneumatic flutter effect encountered at speed that is typical of cars fitted with a sunroof even today.

The story goes that someone at Jaguar eventually tried holding a cigarette packet as an extra deflector at the centre of the roof opening, and this completely eliminated the effect. That is the explanation for the small cigarette-packet-shaped rectangular addition to the deflector.

There were detail changes for the electro-magnetic central locking system, which locked the boot - but didn't unlock it (Jaguar believed that owners preferred it this way, so that no one could get at the boot whilst you were stationary - boot access now came via either the driver lock itself or the interior locking lever (instead of using the rocker switch on the centre console). As was the fashion for the era, there were no fewer than three separate keys that came with the XJ - a master one which did everything except the ignition for which there was a special key, and a "service" key, which left the boot and glove compartment locked.

There were warning lamps to cope with low coolant, rear fog guard and bulb failure covering side lamps and brake lamps (the latter whether a bulb or the handbrake or stop lamp warning switches failed). All except XJ 3.4 models were fitted with halogen headlamps instead of the more expensive-to-replace tungsten sealed filament type. By using vacuum-formed rubber and foam insulation for door panels, bulkhead and propellor shaft tunnel, Jaguar claimed to have improved still further the already exemplary interior quietness of the XJ. The minor annoyance of power steering hisses was reportedly still present on the Series III XJ's, although we believe that Jaguar remedied that problem during the Series III's production run by introducing an extra sound shield between the interior and the rack.

Castle Bromwich Pressed Steel Fisher Paint Plant

The Series III XJ also benefited from the then new £15.5 million Pressed Steel Fisher paint plant at Castle Bromwich, at the time it being the most technically advanced in Britain. Built in the first place to paint the Series III cars, it was sited alongside the body build area itself. Processes included phosphate pre-treatment (both spraying and dipping), electro-priming, primer surfacing (two coats) an "adhesion promoter", four coats of thermoplastic acrylic colour aided by hand application to critical areas, oil sanding and "re-flowing" where'the body was passed through an oven for 20 minutes to give a durable high gloss finish. Added protection was provided with undersealing plus wax injection into enclosed box-sections. There were random inspections, whereby certain bodies were taken aside for a ten-day salt-spray corrosion resistance test.

In 1981 the 5.3 V12 models received the new Michael May designed 'fireball' high compression cylinder head engines and were badged from this time onwards to 1983 as HE (High efficiency) models. In 1982 the interior of the XJ underwent a minor update. A trip computer appeared for the first time and was fitted as standard on V12 models. A new and much sought-after alloy wheel featuring numerous distinctive circular holes was also introduced, commonly known as the "pepperpot" wheel. Also in 1982 a top spec Vanden Plas model was introduced for the US market, a model designation still used today for the top-level XJ saloon in the US.

In 1983 the Sovereign name was transferred from Daimler to a new top spec Jaguar model, the Jaguar Sovereign. The Vanden Plas name was also dropped at this time in the UK market, as the designation was used on top-of-the-range Rover-branded cars in the home UK market. Daimler models became the Daimler 4.2 and Double Six and were the most luxurious XJ Series III models, being fully optioned with Vanden Plas spec interiors.
The 1984 UK model range included the Jaguar XJ6 3.4 & 4.2, Sovereign 4.2 & 5.3, Daimler 4.2 & Double Six 5.3. The last Series III XJ with a six-cylinder engine was produced in 1987.

Production of the Series III XJ continued until 1992 with the V12 engine. In 1992, the last 100 cars built were numbered and sold as part of a special series commemorating the end of production for Canada. These 100 cars featured the option of having a brass plaque located in the cabin. It was the original purchaser's option to have this plaque, which also gave a number to the car (such as No. 5 of 100, etc.), fitted to the glove box, to the console woodwork or not fitted at all. This brass plaque initiative did not come from Jaguar in Coventry. It was a local effort, by Jaguar Canada staff and the brass plaques were engraved locally. 132,952 Series III cars were built, 10,500 with the V12 engine. In total between 1968 and 1992 there were around 318,000 XJ6 and XJ12 Jaguars produced.