Mercedes-Benz 230 SL (W 113), 1963
After Eugen Böhringer had won the 1962 European Rally Championship, beating off tough competition in his factory-prepared Mercedes-Benz 220 SE, the question arose as to which vehicle could be used in future to maintain Mercedes-Benz's leading role in international rallying. Last but not least, Böhringer himself had the greatest interest in continuing his successful driving career in a promising car.
It was clear that the trends of the championship were towards higher power-to-weight ratios of the participating vehicles. Compact two-door cars such as the Saab 96, Volvo 122 S, Ford Cortina GT and, above all, the revolutionary Mini Cooper were ready to seriously challenge vehicles of the calibre of a 220 SE in rally events, despite their considerably lower engine power.
The decision-making bodies of Daimler-Benz AG decided to take a multi-pronged approach to the imminent change in the competitive situation. On the one hand, from the new season onwards, the top saloon among the "Fintail Mercedes", the significantly more powerful 300 SE (W 112), was to cause a sensation in the European Rally Championship and, with unchanged durability, remain clearly superior to its rivals, if not in handling then at least in terms of engine power and suspension qualities.
On the other hand, the company gave in to Böhringer's persistent push to compete in rallying also with a much lighter-footed car. Specifically, he had the use of the brand-new Mercedes-Benz 230 SL (W 113) in mind, whose world première at the Geneva Motor Show in March 1963 was still to come. One motive for this step may have been the intention to sharpen the sporty profile of the new SL – after all, the sports car later often dubbed the "Pagoda SL" had the difficult task of succeeding both the 300 SL and the 190 SL – two SL models whose character could hardly have been more different.
Böhringer had his sights set especially on the internationally highly regarded "Spa - Sofia - Liège" endurance race, which he had finished as overall winner in 1962 in a 220 SE Saloon. The non-stop rally over five days and more than 6500 kilometres had still counted as a round of the European Rally Championship in that year, but was continued as a solitary event that did not count towards the standings in 1963.
The fact that Böhringer regarded the 230 SL as the ideal vehicle for long-distance driving, which was extremely demanding for both man and machine, had good reasons beyond all marketing considerations. The "Pagoda SL" combined hallmark Mercedes robustness with excellent handling and the sporty performance of its six-cylinder engine. In addition, its racing weight was 150 to 250 kilograms lower than that of the 220 SE and 300 SE Saloons. The new sports car therefore had a whole catalogue of advantages that Böhringer wanted to show off for himself and Mercedes-Benz in the rally, which was scheduled to start at the end of August and 90% of which was contested on demanding terrain.
Since the 230 SL, whose German première was scheduled for the International Motor Show (IAA) in Frankfurt in September, was not homologated as a GT vehicle until early November, it had to be prepared according to the regulations of the sports car class. This also had tangible advantages despite potentially stronger competition.
For example, regarding the engine: The six-cylinder in-line engine, which had a little over 2.3 litres of displacement, could be fitted with a different crankshaft that lengthened the stroke from 72.8 to 78.8 millimetres and increased the total displacement accordingly to just under 2560 cc. At the same time, the diameter of the intake and exhaust valve discs was increased by 2 millimetres. To ensure the thermal health of the engine even under the toughest conditions, an oil cooler was also installed. No precise power figures were given at the time, but it is estimated that the revised six-cylinder engine provided a power increase of around 10 to 15% in the "Spa - Sofia - Liège" race compared to the production version, which was nominally rated at 110 kW/150 hp.
This power was transmitted to a 4-speed gearbox adopted from the 220 SE "Fintail Saloon", which had more suitable gear ratios for use in the long-distance race.
In keeping with the spirit of rallying at the time, which was contested with near-production vehicles and had more the character of sporting reliability races, the chassis of the 230 SL was only slightly modified to suit its purpose. At the front, a double wishbone axle with helical springs and telescopic shock absorbers was used. A torsion bar stabiliser was used to limit roll in fast corners. The rear suspension was the traditional Mercedes-Benz single-joint swing axle, which was also equipped with helical springs, telescopic shock absorbers, a torsion bar stabiliser and an additional compensating spring – a design that ensured balanced handling also at high speeds. The brake system with front discs and rear drum brakes was also largely in line with the production standard.
One special feature was equipping of the 230 SL rally car with the particularly resistant, firmer "tropical suspension", which was intended to prevent bottoming out on the largely unpaved roads and protect the car's low-lying components from damage. As had already proved its worth with the rally version of the 220 SE Saloon, the 230 SL could also be fitted with smaller or larger wheels depending on the condition of the ground. In addition to the standard 14-inch wheels, 13- and 15-inch wheels were also available.
The vehicle body proved to be particularly well adapted to high stress. In order to achieve the best possible torsional rigidity, but also for reasons of safety and comfort for the crew, the rally version of the 230 SL, which was actually a cabriolet or roadster, was fitted with a bolt-on sheet metal hardtop. Extensive strengthening measures were carried out in the area of the front and rear shock absorber mounts and the side support of the rear axle. Sturdy shield plates were fitted to the underbody along almost the entire length of the vehicle, protecting all exposed technical components from direct contact with the ground. This also applied to the fuel tank, whose capacity was specially adapted to the requirements of the "Spa - Sofia - Liège" rally and was 100 litres instead of 65 litres as in the production counterpart. To accommodate the different wheel sizes, the wheel arches on the wings were modified accordingly.
The considerable effort that had been made in the Mercedes-Benz sports department under Karl Kling to turn the 230 SL into a rally car capable of winning paid off. Of the 129 entered cars that had started in the Belgian spa town of Spa on 27 August 1963, only 22 saw the finish line in Liège four days later. A host of technical defects and numerous accidents had caused this severe depletion of the field of participants. For Mercedes-Benz, however, there was cause for jubilation: In fact, Eugen Böhringer and his co-driver Klaus Kaiser in their 230 SL managed to win the infamous long-distance contest with by far the smallest time penalty account.
A sensational success, which came about thanks to perfect preparation and outstanding reliability of the chosen racing vehicle as well as a brilliant performance by Böhringer and his co-driver.