Jaguar XKSS '57
The Jaguar XKSS was a road-going version of the Jaguar D-Type racing car.
Well over 20 years after Bentley had dominated at Le Mans another British make stood up to the 24 Hours challenge; Jaguar. In charge of development of Jaguar's first post-war sportscar was an old 'Bentley Boy', Walter Hassan. With the alloy bodied version of this sportscar, the XK 120, Jaguar scored their first racing successes. Although these results were promising, Hassan and Jaguar founder William Lyons found more was needed to win at Le Mans and production of a competition version of the XK 120 was started.
Shown to the public for the first time at the 1951 Le Mans tests, the XK 120 C or C-Type looked ready for the challenge. It shared its XK straight six engine with the XK120 production model, but sported a much lighter tubular frame chassis. In competition tune, breathing through three Weber Carburetors these engines were good for 210 bhp. Although two of the three C-Types entered failed to finish the 24 Hour, it was a good weekend for Jaguar, with the remaining car finishing well ahead of the competition.
For the 1952 24 Hours race Jaguar fielded an experimental, un-tested long tail, low drag C-Type. Overheating problems caused all three cars to drop out early in the race. No risks were taken for 1953 race, where Jaguar fielded more conventionally bodied C-Types. The works cars were among the very first equipped with disc brakes, giving them a clear edge in the race and another win for the boys from Coventry. In the meantime Jaguar worked hard on a completely new model to continue the company's successful endurance racing campagin.
By the spring of 1954 the new car was running. Although it had no official name but names like C-Type Mk II and D-Type were rumoured, the latter stuck. It was the first Jaguar to use a monocoque type chassis. Attached to the monocoque was a front subframe, carrying the engine and front suspension. On the six cars built in 1954, the subframe was welded to the monocoque, but on later cars it was bolted on for easy detachment. Of course the disc brakes from the C-Type were carried over.
Jaguar again relied on the XK engine, but some modifications were made to limit frontal area. The sump was halved in height by switching from wet to dry-sump lubrication. The engine was also mounted at an 8-degree angle, with the off-centre bump in the engine-cover as a result. Mechanically, the only difference between the 1954 and 1955 works cars was the use of larger valves on the latter. Extra space was required to house the larger valves. Frontal area was not sacrificed as the 1955 works D-Types were the first Jaguars to use an asymmetrical head that would come to be known as the '35/40 head'. The intake valves were mounted at 35 degrees, whereas the exhaust valves were mounted at 40 degrees.
As mentioned earlier, a small frontal area was high at the Jaguar priority list. This was to allow for high top speeds at the long Le Mans straights. To ensure stability at speeds of over 150 mph, the D-Type was equipped with a big fin behind the pilot's headrest. Works cars built in 1955 were equipped with a longer nose for even higher top speeds. This was very indicative of Jaguar's strategy, which had Le Mans as the only priority and D-Type drivers often suffered on slower tracks, where the slippery bodies offered no downforce what so ever.
Three cars were entered in the 1954 Le Mans 24 Hours. Although the Jaguars were on the pace, it was not enough to match the 4.9 litre Ferrari of Gonzales / Trintignant. In 1955 Jaguar returned with the large valve engined long nose D-Types to take the marque's third victory. They faced strong competition from the high-tech Mercedes-Benz SLRs, but the German team withdrew after one of their cars was launched into the crowd, killing dozens of spectators. The organizers nevertheless decided to continue the race.
At the time of Mercedes-Benz' retirement, the top op placed Jaguar of Mike Hawthorn and Ivor Bueb chased the leading SLR of Moss and Fangio by two laps. Now that they were out, there was little competition for Jaguar, especially as all of the powerful Ferraris retired due to accidents or mechanical failures and the Brits claimed their third Le Mans win. In the following two years, Jaguar's colours were successfully defended by the Ecurie Ecosse team. In 1956 the Works cars crashed out early in the race and Jaguar had given up on racing altogether in 1957.
Rule changes, limiting the displacement to 3 litres, left the D-Types pretty much obsolete for 1958. Jaguar did supply a three litre version of the XK-engine, but it was no match for the competition. Dozens of short-nose production D-Types were sold to privateers, which successfully campaigned them on both sides of the Atlantic. To get rid of the remaining chassis, Jaguar equipped them for road use and sold them as the XKSS model. After only sixteen examples were produced a fire in the factory abruptly ended the run. With three Le Mans wins, the Jaguar D-Type remains as one of the most successful racing cars ever. In both road going XKSS and racing D-Type guise, it is also one of the most desirable Jaguar models.
Specs:
- Jaguar XKSS '57 specs.png (6.92 KiB) Viewed 1091 times
