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Commensurate with the repositioning of the radiators, the large NACA ducts were removed from the top of the door sills. Aerodynamic changes included the repositioning of the combination of oil/water radiator to the nose of the car, which allowed the use of a modified splitter plate. The rear suspension changed from vertically positioned spring/damper units arranged over the top of the gearbox to a horizontal layout aligned with the longitudinal axis of the car. The C9 was a development of Sauber's previous C8 design, retaining a monocoque that largely consisted of aluminium, although considerably stiffer and with numerous other improvements. The Sauber C9 (later named the Sauber Mercedes C9 or Mercedes-Benz C9) is a Group C prototype race car introduced in 1987 as a continuation of the partnership between Sauber as a constructor and Mercedes-Benz as an engine builder for the World Sportscar Championship.
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