Motor

Go dirt with the legendary Rally Car Porsche 959 │ show the world an excellent four-wheel drive system

This articlePorsche 959 facing a severe long-distance rally | Engine, body structure?]Is continued.

The transmission of the 959 is made by BorgWarner. For reference, it is a transmission with the code name of type 950, which was also used for the production 911. When the 959 was still in its design phase, it decided to introduce this six-speed gearbox assuming that it would be used as a rally car, but a special gear ratio was required to run Paris-Dakar, which was added As a result, the weight of the car increased, and the overall length of the body was extended, leading to packaging problems. To avoid that, one of the six gears was hit with an extremely low ratio. Therefore, in fields other than deep snow and muddy fields, the remaining five steps had to be covered.

The primary objective of the entire project was to allow Porsche to be active in Group B for both rallying and circuit racing. The 959 was tested hard to ensure that the cracking problems found in Paris-Dakar in 1984 were never again encountered. The 959 was treated as a special car due to its name and body style, but the Paris-Dakar entry car was quite different from the production model, with a lightweight plastic body panel reinforced with Kevlar. The engine is derived from the naturally aspirated Carrera 3.2, but the crankcase has been changed from the original aluminum casting to magnesium casting. However, in the opposite case, the normal 959 drivetrain is magnesium-cast, while the Paris-Dakar model has been reworked from rigid aluminum.

The PSK system was continuously adopted and combined with the rear differential [the 953 spool system was discontinued], allowing the driver to increase the setting range. This allowed the driver to control both differentials freely, and could run with very little or no front lockup, with 40-50% rear lockup. With the ability to adjust the front and rear torque distribution, drivers who like 50:50 distribution in the high-speed section could easily increase the rear bias in situations where they wanted to swing the car. However, in the second year, even with a new car in Paris-Dakar, he was able to finish sixth.

The 959 fully demonstrated its dirt abilities, but what about the pavement and the ability to compete in endurance races? Its role was taken by the Type 961, a 959 tailored for circuit racing. Since aerodynamics is more important in the circuit race, Helmut Fregel, the leading figure on the road, was in charge of the development of the 961. The only way for the production 959 to get downforce was to raise the tail slightly and lower the nose, but this method raises the center of gravity and is not suitable for race cars at all.

Fregel spent six months using a computer to explore the aerodynamic style the 961 should have, and let the team conduct a wind tunnel test on a 1/5 scale clay model. The 961, which raised the 959 multi-valve 6th generation twin turbo engine to 600 bhp, was able to make up for the Le Mans Test Day in May 1986, but the driven Rene Message was straight and stable in Junodiere He pointed out the lack of performance and the unstable behavior at high-speed corners. The cause was in the rear suspension mount rather than aerodynamics.

The 961 was the first four-wheel drive vehicle in Le Mans. The FIA ​​did not allow four-wheel-drive vehicles in its class, but could run Le Mans as long as it met the IMSAGTX regulations. The entry at the IMSA GTX also had the speculation that Porsche wanted to sell the 961 to US customers.

The race ended with great success. Despite only one race, the 961 finished in sixth place, and the top five cars were all Group C cars, indicating how impressive they were. For Porsche, this is the result of being able to show off their technical capabilities to the fullest.

The two events Paris-Dakar and Le Mans have shown that Porsche's complex four-wheel drive system is among the best in the world. Of course, due to the high cost, it could not be directly introduced into mass-produced vehicles for general use, but there is no doubt that the experience gained there has been used in the later 964 Carrera 4, etc. Four-wheel drive technology is going to make Porsche brilliant today and in the future.


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