24 June 2011

Racecar Of The Day - Sauber Mercedes C8/C9/C11

One of the first specialist manufacturers to build a Group C racer was Peter Sauber. This Swiss engineer and motor racing enthusiast previously constructed mainly small-engined sports-prototypes, so Group C was quite a step forward. He had teamed up with engine specialist Heini Mader and together they created the Cosworth engined Sauber C6 in 1982. The car looked very purposeful, but the badly vibrating V8 engine proved to be a reliability nightmare. In the following seasons, the Swiss team had a little more success with the BMW engined C7, but they could not match the Works developed Porsches and Lancias. The C7's biggest achievement was a ninth at Le Mans in 1983; preventing a complete Porsche top-ten. Perhaps with the intention of securing factory backing, Peter Sauber asked Mercedes-Benz if he could use their brand new windtunnel to test his latest racing car. The Germans were clearly impressed and shortly after the wind tunnel test an exclusive engine deal was signed between Sauber and Mercedes. This effectively meant the return of Mercedes-Benz to Sportscar racing for the first time since their withdrawal after the tragic 1955 Le Mans. The priority was to develop a race winning engine first before drawing too much attention and in the first few years of the cooperation, Mercedes-Benz was listed as an engine supplier only.

The Sudamerika-Sauber C7; 1983 Le Mans

Sauber was particularly interested in the recently introduced, all-alloy 5 litre V8 engine, known internally as the M117. Mader was commissioned to turn this street engine into a full Group C powerplant by adding two KKK Turbochargers. With Group C fuel limitations in mind, the engine was not only developed for outright performance, but also to get sufficient mileage. In qualifying trim the engine easily produced 700 - 800 bhp, but in racing spec 650 bhp was the more sensible output. The newly developed twin-Turbo V8 was mated to a familiar Hewland five speed gearbox. For the first Sauber Mercedes, the C8, Peter Sauber used the C7's aluminium monocoque as a basis. The Mercedes engine was mounted in a steel subframe directly behind the driver's compartment. All the other running gear was very conventional with independent suspension and vented discs all-round. Subject of the windtunnel test, the ground-effects body was indeed very efficient, although not very stable. At Le Mans in 1985 the sole Sauber Mercedes C8 entered recorded the second highest top speed, but also flipped on the Hunaudieres in practice. Although the car landed on its wheels, it was damaged too much to start the race.

The Sauber team returned the following year with two new C8 chassis run by Kouros Racing, named after the fragrance brand of its sponsor, Yves Saint Laurent, although officially backed by Mercedes-Benz. Both cars managed to start the race, but retired with engine and gearbox problems before night fell. Tweaks to the aerodynamics had made the cars more stable on the straights, but they weren't quite as fast as in 1985. One of the C8s was sold to privateer Noel del Bello, while Sauber and Mercedes were busy working on a replacement for the 1987 season. The C8 was raced twice more at Le Mans by the Frenchman, but again with little success.

C8 at '86 Le Mans
Logically dubbed the C9, the new-for-1987 car (again liveried in the dark blue Kouros colours), was again a development of its predecessor, modified in detail only. The rear suspension and the body were brand new, whereas the engine was a further Mader development. They managed a mere twelfth in the teams standings, scoring points in only a single round. The Saubers made a better impression at Le Mans in 1987, qualifying seventh and eight. In the opening stages of the race, Johnny Dumfries was running as high as fourth before retiring with a gearbox problem after only 37 laps. The second car faired not much better, eventually succumbing to its second drivetrain related problems at around midnight.

C9 at Le mans '87 -  Johnny Dumfries is the driver. The same car would be driven in the USA by Chip Ganassi, he of CART fame
The Baldi/Weaver car on the way to third place at Silverstone
Sauber-Mercedes C9 rounding Becketts corner at Silverstone during the 1988 Silverstone 1000 km
Surprisingly, Mercedes-Benz was not deterred and dramatically upped their involvement in 1988 to full factory backing. Kouros was dropped as a sponsor, forcing the team to be renamed Sauber Mercedes. As a result, Mercedes used AEG-Olympia for sponsor – AEG being owned by Daimler-Benz at the time. The changes paid off immediately as a Sauber Mercedes C9 was driven to victory in the Jerez 800 km, one lap clear of the dominant Silk Cut Jaguars. They also managed to finish second in the championship behind those Jaguars with five wins for the season. Unfortunately at the 24 Hours of Le Mans, the team suffered an embarrassing setback when both C9s were forced to be withdrawn before the start. The combination of higher speeds and higher downforce had increased the loads on the Michelin tyres too much, causing the rear tyres to burst on one of the C9s at very high speed during qualifying. Starting the race was considered too dangerous.

Sauber C9 at Oldtimer-Grand-Prix 2009 at Nürburgring

Finally, in 1989, the car was able to achieve great success. Mercedes-Benz replaced the older M117 5 litre turbocharged V8 with a new version, known as the M119. The biggest change was four valve aluminium heads with double overhead camshafts. This bumped the power to 720 bhp and 810 Nm in race spec. The new quad-cam V8 engine was fitted to the proven C9 chassis. The Germans' involvement in the Sauber program was visibly increased as the cars were now painted silver; a clear drawback to the successful Silver Arrows of years past.

The C9 was able to win all but one race in the 1989 season, including the 24 Hours of Le Mans. Reaching 248.0 mph (400 km/h) during the qualifying sessions of the 1989 24 Hours of Le Mans, the Sauber C9 has set one of the fastest top speeds ever in the history of the competition at Le Mans. These speeds led to the cessation on the huge Le Mans Mulsanne Straight and the introduction of two chicanes, from 1990 onwards. The C9's top speed was only beaten by the WM Peugeot prototype, with a speed of 251.1 mph (405 km/h) in the 1988 race. However the WM, optimized for a low drag setup and high straight line speed, suffered from handling problems elsewhere on the circuit and the engine was prone to overheating. Indeed the car's fastest time was set with tape applied over the ducting for aerodynamic purposes and was withdrawn as soon as a new record was set to avoid an expensive rebuild.

For the fifth Sauber Mercedes attempt, the team again fielded two cars. All of the four difficult previous editions were quickly forgotten as the two cars were placed first and second on the grid. After a trouble free race, the two cars crossed the line in the opposite order, clinching a convincing one-two victory. The winning C9 was driven by Jochen Mass, Manuel Reuter and Stanley Dickens. The team kept the Le Mans winning form for that season's World Championship and with seven wins out of eight races, they were crowned World Champions at the end of the season. Encouraged by the good results, Sauber developed a brand new car for 1990. The aluminium monocoque was replaced by a more modern and rigid carbon fibre one. The C10 name was skipped because it was difficult to pronounce in German, so the new car was dubbed C11. Much of the running gear, including the M119 engine, was carried over from the C9. Surprisingly the Swiss/German team did not return to Le Mans and instead focused on defending the World Championship. They did so with visible ease, with the last race of the season being won by Jochen Mass and a young Michael Schumacher.

For the 1991 season Sauber developed the flat-12 engined C291, in accordance with the new F1 inspired 3.5 litre Group C regulations. Nevertheless, the C11 was brought back from retirement for Le Mans, but the flawless race of 1989 proved to be the rare exception as all three 'Silver Arrows' fielded retired with mechanical issues. At the end of the season, both Sauber and Mercedes-Benz withdrew from sportscar racing to focus on Formula 1.

The C11in Dijon in 1990 with the duo of Jochen Mass/Michael Schumacher on the way to 2nd place

The troubled C291

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