Series III’s advent coincided with a number of technical innovations, but one in particular would come with a side-order of calamity.
Despite the outwardly positive manner in which the Series III was presented to the motor press, there was no getting away from the political environment under which the car was developed. Jaguar was reeling under the dictates of the infamous Ryder Report, a series of post-nationalisation recommendations which as implemented, stripped Browns Lane of its leadership, its identity and ultimately its ability to function as a carmaking business.
As documented elsewhere, the remaining senior Jaguar staff – predominantly from within engineering – began enacting a policy of non-co-operation and obstruction; essentially carrying on as best they could by simply ignoring BL management and their increasingly nonsensical integrationist dictates.
Jim Randle: “You have to remember, this was a group of people that wanted to expunge the name of Jaguar from the group. You can see to some degree the logic – that they wanted to make the whole thing uniform – but what it did to people’s morale was just ridiculous.”
This engineering-led siege-mentality served to preserve a semblance of team spirit and would allow Series III to retain a strong marque identity. However, the prevailing view amid BL’s product planners was that in a post oil-shock landscape the business case for the type of luxury cars Jaguar made had been lost. Better surely to concentrate resources upon the forthcoming ‘corporate executive’ Rover SD1 programme and allow Jaguar and their decadent range of automotive dinosaurs to wither away.
The counter-arguments posited by Jaguar’s acting chief executive (engineering chief, Bob Knight) must have been something to hear – especially in the febrile atmosphere of the newly constituted and financially straitened BL Cars division of nationalised British Leyland. Nevertheless some £7 million was eventually earmarked for the programme, dubbed internally as XJ50/51/52 – each iteration referring to the relevant engine capacity.
Whereas the most obvious alterations were either stylistic or marketing-led, a number of significant engineering changes also took place beneath the XJ’s revised skin. The most significant of these related to the 4.2 litre version of Jaguar’s venerable XK in-line six. Having become somewhat emasculated from its 1960s incarnation, Jaguar’s mainstay power unit had been detuned to improve emissions and fuel efficiency, by mid-decade producing a mere 172 bhp at 4,700 rpm. With US-specification emissions equipment, this figure had fallen further still.
However, the development of the joint Lucas-Bosch L-Jetronic fuel injection system allowed engineers under powertrain chief, Harry Mundy to raise the 4.2’s compression ratio from 7.8 : 1 to 8.7 : 1 (8.1 : 1 in catalyst form) with modified pistons, larger inlet valves and alterations to the valve timing. These revisions saw maximum power leap to 205 bhp at 5000 rpm and torque to peak at 236 lb/ft at 3750 rpm, restoring the engine’s somewhat blunted performance to that of its Series One predecessor. A new, thicker head gasket also aimed to improve the 4.2’s noted propensity to blow its top.
Mundy’s engineers had further developments up their sleeves for the fuel-hungry, if hugely refined 5.3 litre V12 unit, but they would be subject to the provision of additional BL funding and further hard-fought battles on the part of the chain-smoking Mr. Knight. Meanwhile, the entry-level 3.4 litre unit (which only really appealed to the UK market) continued unaltered.
The next major engineering change to the Series III was perhaps the first and most notable piece of BL hardware to find its way beneath Browns Lane’s finest. Some years previously, Mundy had developed a five-speed manual gearbox capable of handling the torque output of the V12. Believed to have been a fine transmission, it fell foul of BL’s straitened finances and customer preference for automatics. In its stead, BL offered a smaller (if related), 77mm gearbox, developed by Rover for the SD1 programme.
While this was found to be acceptable, its quietness in operation was anything but, necessitating the use of a stronger layshaft, bigger bearings and a needle roller bearing for reverse – all of these changes being applied to Rover gearboxes as well. The latter development had already been specified for Rovers supplied to the UK’s traffic police, “for reversing 40 miles up the M1”, Mundy told Autocar with his tongue no doubt wedged firmly in his cheek.
The advent of this transmission, available for the 3.4 (XJ52) and 4.2 (XJ51) models meant the demise of Jaguar’s own four-speed unit – a knock-on effect being the end of the manual transmission XJ-S, as the Rover transmission could not handle the V12’s torque.
Since the early 1970s, Jaguar management had agitated for investment into a modern paint plant at the Browns Lane factory to replace the existing facility which dated back to the 1930s. Hampered by poor finish and a lack of colour choice, Jaguar’s upmarket image was being tarnished. During his short reign as Managing Director, Geoffrey Robinson took matters into his own hands while his BLMC bosses prevaricated, commissioning Italian firm, Interlack to construct a new paint plant at Browns Lane as part of a vast expansion plan, ordering the structural steel during the latter months of 1974.
But following the collapse of the BLMC business and the strategic vacuum created by the Ryder report, the massively expensive project ran aground, with nobody prepared to commit the £14million required. Instead, the unused steel girders sat rusting in the Allesley rain for several years, eventually being sold off for scrap – a grim reminder not only of Robinson’s brief and controversial tenure, but of the leaping cat’s derailed expansionist hopes.
There matters were left until the newly constituted BL Cars initiated the SD1 programme. Intended to serve Rover, Triumph and Jaguar, a new paint plant was finally commissioned in 1976 at a cost of £15.5 million at Pressed Steel’s Castle Bromwich facility. Claimed to be the most technically advanced in Britain when it was inaugurated in 1978, it was sited alongside the Jaguar body facility, which meant unpainted shells would no longer be required to be transported and stored at Browns Lane.
Deaf both to Jaguar’s entreaties in relation to the plant’s site, or to the loud objections levelled from both management and unions to the proposed ‘Thermoplastic Acrylic’ (TPA) paint process, the new facility went ahead. On paper it all sounded impressive. Bodies were to receive a phosphate pre-treatment – both spraying and dipping – electro-priming, two coats of primer, four coats of acrylic thermoplastic colour, oil sanding and ‘reflowing’, where the painted body was baked for 20 minutes, which promised a high quality, durable finish.
This would not necessarily prove to be an issue with the Rover’s up to date body-in-white, but it wholly neglected to account for the manner in which Jaguar’s bodyshells were constituted. Made up of hundreds of small pressings welded and in the case of the external skin panels, lead-loaded for a smooth seamless finish, it was to prove hopelessly unsuited to the new paint process, but BL management had long ceased paying attention to the troublesome occupants of the increasingly turbulent Large Car Plant Number Three.