Jaguar XKSS: a road-going variant of the XK-D race car that won the 24 Hours of Le Mans in 1955, 1956 and 1957.
In 1954, Jaguar replaced their C-Type race car with the D-Type, bringing aircraft technology to road racing. The D-Type shared many of its mechanical components with the C-Type, including the inline six cylinder engine, but the structure of the car was radically different. The D-Type’s aircraft-style monocoque body construction was the brain child of Malcolm Sayer who had come to Jaguar from Bristol Aircraft after World War II. The aircraft space frame-style body construction allowed a very sleek, wind-cheating shape. This resulted in Jaguar D-Types winning the 24 Hours of Le Mans in 1955, 1956 and 1957.
The D-Types had a longitudinal body brace between the seat for the driver and passenger. There was a bulge in the hood to accommodate the ram tubes feeding the triple two-barrel Weber carburetors. To help achieve the desired low frontal area, Jaguar chief engineer William Haynes and former Bentley engineer Walter Hassan canted the engine 8½º and developed a dry sump lubrication system for the engine which lowered the engine height by eliminating the usual oil pan. At Le Mans, the long Mulsanne Straight is travelled at full throttle. With that in mind, a fin that began at the driver’s head rest and extended to the rear edge of the car was incorporated to aid stability.
1955 Jaguar XK-D: ancestor of the XK-E, which was also built with monocoque construction.
In late 1956, Jaguar temporarily suspended its factory racing efforts, leaving the company with an inventory of 25 D-Types. Looking for a way to take the car racing in Sports Car Club of America competition, American racing legend Briggs Cunningham approached Jaguar with the idea of turning the remaining D-Types into road-going automobiles. Another 25 were needed to reach the minimum production quota for SCCA homologation rules, and Jaguar agreed to build them. Thus the XK-Super Sport (XKSS) was born.
For the XKSS, the longitudinal brace between the driver and passenger seats was removed as was the fin. A taller, chrome-framed windscreen was fitted along with chrome bumpers, a passenger door, turn signals, side windows, larger taillamps, and a crude folding top. A few were fitted with a chrome luggage rack. The D-Type’s 3.4-liter inline-six, rated at 250 horsepower and mated to a fully synchronized four-speed transmission, carried over intact, giving the XKSS a 0-60 time of 4.7 seconds and a top speed of 146 MPH. To slow all that “go” the D-Type’s disc brakes were retained. The XKSS was first shown in the U.S. in the 1957 New York Auto Show in December, 1956. It was priced at $7,000, making it as expensive as two Chevrolet Corvettes. Nonetheless, orders were taken for all 25 units.
On 12 February 1957, with 16 of the 25 XKSSs having been completed, a fire began in a tire storage area of Jaguar’s Browns Lane plant in Coventry, consuming much of the assembly area before being brought under control. Among the cars destroyed in the flames were the nine remaining XKSSs along with the assembly jigs needed to build the cars. The fire compromised the production of Jaguar’s regular car line, forcing the suspension of construction of the remaining XKSSs. Now, nearly six decades later, Jaguar once again has a shop set up for the production of low volume specialty cars, the Jaguar Classic Experimental Shop in Warwick, and has announced they will finish production of the nine XKSS cars lost in the 1957 fire.
The nine continuation models will be constructed to the exact specifications as the originals, and will be priced “in excess of” £1,000,000, or some U.S. $1.41 million at current exchange rates. Deliveries are expected to begin in early 2017.
This 28 minute video gives a detailed description of the assembly of Jaguars in the famed Browns Lane, Coventry factory. The cars were built with a degree of hand work seen today only in specialty builders such as Morgan.