Leaping Jaguar

Welcome to Leaping Jaguar

The distant year of 1972 was a year full of stories, Bloody Sunday, Watergate, Munich Massacre, Godfather and SALT 1. Among all these news, an astonishing motor car emerged in July, threatening the Jaguar XJ6 as the Best Car in the World.

Welcome the Jaguar XJ12, brainchild and favourite cat of Williams Lyons, Jaguar's boss. Sporting the famous all alloy OHC V12 engine, displacing 5343cc and producing 309BHP SAE, 147mph top speed with 0-60 in 7.4 sec, making it the fastest four door on earth (and the most beautiful). It was an immediate success only dampened later by the 1973 Energy Crisis.

After the abandon of Le Mans racer XJ13 V12 DOHC project due to British Leyland pressures, Walter Hassan (Bentley, Coventry Climax), Harry Mundy (BRM, Coventry Climax, Autocar technical editor) and William Heynes turned their attention to produce a road going V12 engine. It was required to be cost effective to manufacture, obey future US emissions legislation and still produce adequate torque figures, more important than outright power on a luxury four door saloon, as the incoming XJ4 project was always intended to receive the V12 engine.

Several prototypes were experimented, including single cylinder engines to analyse different combustion chambers shape. Although the DOHC Hemi version produced incredible amounts of power (in excess of 500BHP), it was found that an OHC Heron head engine had similar if not superior torque figures up to 5000rpm, making it nicer to drive on a luxury four door saloon.

Jaguar Growler

Unfortunately, due to Brico Ltd failing to develop a Fuel Injection system for this engine and other technical difficulties, the introduction of this engine was delayed, only first seen on the 1971 SIII E-type sports car, so in 1968 Jaguar was forced to re-use the venerable if somewhat ancient (introduced in 1948) straight six XK engine in the XJ6, the reason why all XJ series sport a central hump in their bonnets!

When Jaguar introduced their Jaguar XJ6 in 1968 it took the motoring world by storm, setting unprecedented standards in the industry. Here was a car that handled better than a sports car and was more comfortable and quieter than a Rolls Royce Silver Shadow, for a fraction of its cost! Such was the demand for this car that a black market developed itself for it, causing such strange actions as a group of Swiss gentlemen travelling on purpose to protest at Jaguar London headquarters as they couldn't obtain a XJ6 back home!

Bob Knight, William Heynes and Tom Jones (not that one) were the men responsible for the engineering side of this beauty. Knight once mentioned that in his childhood, he was often mesmerised by the elegance and silence of Rolls Royce and other alike that would pass by him in Mayfair, London. It has driven him to develop the best car in the world, surpassing Rolls Royce and the Mercedes Benz's Teutonic austerity.
The XJ featured the famous Jaguar independent rear suspension with its four shock absorbers (IRS), limited slip differential (Salisbury 3.31:1) with the brake discs attached to it to reduce unsprung weight at the rear wheels. The front suspension possessed built-in anti-dive geometry and ventilated discs with three pot callipers developed later into 4 pot. All encased in sub-frames completely detached from the bodywork by Metalastick bushes, isolating further road noise and harshness of suspension movement. There's a double bulkhead (Lyons insisted on it) to further isolate the cabin from outside noise.

Williams Lyons personally instilled his styling genius in the XJ, making a worthy car to the Grace, Space and Pace Company's motto. The original XJ represents the acumen of Jaguar styling and engineering best efforts, with the elegant yet aggressive design by the legendary Lyons' talent, who hardly drew but used his company's carpenters to do mock ups until he felt the shape was right. It was so low in fact that Bob Knight once remarked as he stood by the car with Lyons, that if you came running out the house, you may trip over the car!

In these next few pages, you will find all kind of information relating these sublime automobiles and my personal odyssey to resurect my own XJ12 back to life!

As LJK Setright once famously announced:

Drive On!

Web Design by Edgar Marques

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