Friday, 11 May 2012

Porsche 911 SC RS in retrospect

One of the most disappointing aspects of the Porsche 911 SC RS as a factory rally car was it’s total lack of development.
When I had first met Jürgen Barth at Porsche Weissach to discuss this car, he told me they would make a complete rally version of the car, drawn from all Porsche’s previous rally experience. At that time 1983, Porsche had successfully rallied the Porsche 911 and won numerous events and even the East African Safari with Bjorn Waldergard driving, which was the toughest rally in the world at that time. A host of internationally known rally drivers had driven Porsche 911 variants previously and rallying had been successful well established for Porsche winning the RAC, Monte Carlo, so I took this in good faith that we would indeed have a great rally car, fit for purpose.
In order to homologate the new 911 SC RS cars, they were to be manufactured in lightweight road trim. Jürgen told me Porsche would sell us all the proven special rally equipment to easily modify the car into full rally trim.
However in reality, Porsche had not built a new 911-rally car for many years and unfortunately it showed up when we set to work on preparing our car.
An example of this was the SC RS had cast aluminium-trailing arms that did not flex; the old 911 rally cars had steel ones that did to some extent, however this was a weakness we assumed would have been designed out in the new car. So when the car ride height was greatly increased, all the suspension angles changed and the only place the rear-trailing arm could flex was in its rubber-mounting bush on the chassis pickup point. This movement was extremely limited and so the arm was under stress all the time, so I’m afraid not an acceptable engineering design to start with.
On the Kuwait rally, Saeed Al Hajri snapped a rear-trailing arm completely in two parts and had to retire. Later after discussing this with David Richards we added rose joints to the pickup points to solve this problem, but I am not sure if these were legal or not. It was very disappointing that Porsche had not foreseen this issue and engineered the 911 SC RS accordingly.
The other main flaw with the Porsche 911 SC RS, was its total lack of chassis strength. As Porsche were building these 20 homologated cars, especially for rallying. I would have thought Porsche would have really strengthened the cars during production process. Jürgen told me sometime later that they cars had indeed been specially strengthened, but Dave Richards told me this was nonsense as Prodrive had the completely rebuilt the front-end chassis of several cars in Europe and the Middle East having previously been twisted and bent them completely out of shape!
Another serious issue was the air cleaner box did not fit correctly and the sand and dust got drawn into the air intakes ruining the engines, requiring a rebuild after the first event. The air boxes on early roads cars down the years were well designed and well built, but in the 911 SC RS the air box was seriously lacking rigidity to seal correctly. We ended up putting silicone sealant around to seal it but this was always a problem it the air box ever had to be removed during an event.

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