When Joest outfoxed Porsche
As we approach the 100th running of the 24-hour classic, Total 911 looks back on key moments from La Sarthe
After its surprise victory at Le Mans in 1981, Porsche returned to top-flight motor racing in the new Group C with its 956. Following its first season in 1982, the 956 would be made in relatively large numbers for sale to private teams.
As it had with the 934 and particularly with the 935, Porsche retained its competitive advantage by selling off the previous year’s design. As Derek Bell later discovered, the private teams had nothing like the resources of the works teams. Always having the dominant car, Porsche knew this and was confident its hegemony wouldn’t be threatened.
In 1984, Weissach developed the 962, which differed essentially from the 956 by having a longer wheelbase. This enabled the pedal box to be moved behind the front axle to conform with new US safety regulations, because Porsche wanted to continue racing in North America as well. As the 1985 season began, the newly developed 962C showed a clean pair of heels to the opposition. A perverse ruling by the FIA at the outset of Group C had been the restriction on petrol consumption. For 1985, this was limited to 51 litres/100km for all races except for Le Mans, where (as usual) France’s ACO had its own rule, restricting consumption to 44 litres.
One man who smelled an advantage here was a certain Reinhold Joest. A seasoned racing driver, he retired in 1981 and set up his own Group C team. By the mid-1980s he was probably the most sophisticated of the private entrants and winning Le Mans was his objective. In practice, the works 962Cs were fastest, but once the 24 hours were underway, to keep within the 44 litre/100km limit, they simply couldn’t lap fast enough to keep up with the Joest 956.
To Porsche this was an affront, especially because a Joest 956 had beaten the works 956 the previous year. The Weissach men cried foul, appealed to the ACO and an incredulous Valentin Schaeffer, the man who had overseen the development of Porsche’s Group C engines, stormed into the Joest pit. Despite close attention of every refill of the Joest car, the
ACO could find no anomalies, although this didn’t stop it from confiscating all of Reinhold’s metering equipment after the race for further investigation. It was returned months later without comment.
Reinhold had calculated brilliantly. Porsche’s 962 was soundly beaten, with his 956 finishing seven
laps ahead of the first works 962C and marking the second victory of the 16 that Joest Racing had now scored at Le Mans.
Finally, in 2015 Reinhold explained how he’d prepared that 956. Changes to Porsche’s ‘customer specification’ were considerable: the block, pistons and camshafts were all reworked and the compression ratio raised from Porsche’s advised
8.5:1 maximum for the 2,659cc 935/7 engine to 8.9:1; the stock Bosch ECU was replaced (a bespoke item was expensively developed); and extensive wind tunnel studies led to changes including larger Venturi intakes and faring of the chassis to evacuate heat from the engine more efficiently. Sachs was approached to reconfigure the stock Bilstein dampers which, like the bespoke ECU, was a time-consuming undertaking. Having paid Porsche $250,000 for the 956, Reinhold probably spent as much again on these modifications.
By reducing consumption by 10 per cent, Reinhold had comprehensively beaten Weissach. The following year, the FIA would dispense with its fuel restriction policy and the factory 962C would resume the dominance of the previous works 956s. But the warning to Porsche that technically it wasn’t invincible was salutary: the photograph (below) shows the consternation in the Porsche pit as the realisation sank in that they’d miscalculated. Helmuth Bott and Peter Falk look bewildered, Paul Hensler, right, is a picture of dejection and behind them Jürgen Barth appears to be telling Valentin Schaeffer that it was all his fault.