‘SL’ stands for ‘Super Light’
Less weight means less fuel consumption… and means also greater agility and even more motoring enjoyment. This is especially true of sports car models. And it is for this reason that the developers at Mercedes-Benz decided four years ago to build the carosserie of the next generation of SL models not from steel but from aluminium. Suddenly ‘SL’ takes on a new meaning… ‘Super Light’. The timing of the car maker could hardly have been better, with the subject of light weight construction dominating the chatter within the automobile industry. After Audi and Jaguar, Mercedes is the third manufacturer to use the light metal in its series production. In the concern’s factory in the city of Bremen a completely new and fully automated assembly line has been installed. Its capacity is forecast to be over a hundred cars per day. Mercedes’ own presses will produce components such as the aluminium bonnet hood, wheel-arches, doors and the car's side panels. Other parts such as cast structural elements will be sourced from third-party suppliers.
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- The new SL has the internal designation ‘R 231’ and it is to have a kerb weight 140 grams less than its predecessor (R 230). Of this saving 110 kilos is the result of the use of aluminium for the carosserie.
Advantages only
The new SL has the internal designation ‘R 231’ and it is to have a kerb weight 140 grams less than its predecessor (R 230). Of this saving 110 kilos is the result of the use of aluminium for the carosserie. The warp and torsion resistance of the naked frame is increased by 20 percent. “Our aluminium structure weighs just 254 kilograms and is in every way superior to the steel version”, says Thomas Rudlaff, who heads the aluminium fabrication operation, “this is true in terms of the rigidity, the safety and also in terms of the vibration characteristics.” However the SL does not quite achieve a hundred percent aluminium content ratio… to enhance roll-over safety the ‘A’ pillar and the windscreen frame are reinforced with steel.
New techniques
Compared with rival car makers Mercedes is to a great extent employing new welding and joining techniques and unique structural elements. The motto… the right material at the right place in the right amount. Thus it is that the forward longitudinal members are made of so-called hydroform profiles, the side skirts of seven-chamber extruded sections and the central tunnel from ‘tailored welded blanks’ of various thicknesses. The front end wall of the SL is according to Rudlaff the most substantial aluminium casting ever used in automobile construction and has the result of allowing the build to be completed with fewer individual components. The car’s flooring is made of four centimetre thick sandwich plate, firmly attached by friction stir welding.
Concert hall on wheels
The Mercedes engineers have put something a bit special in the front foot-well of the SL. The cast structure associated with the rear engine compartment wall, the wheel housings and the longitudinal members is so stiff that here a big bass woofer has been installed… something never before an element of car construction. The result is that there is a cavity with a resonance volume of 17 litres. This acoustic trick permits a sound quality never before achieved in an automobile and which will make even of the Roadster a four-wheeled concert hall.
It’s almost magic
As before the sixth generation of the SL will have an electro-hydraulic hardtop which will vanish into the boot in 15 seconds. New is the so-called ‘Magic Sky Control’ glass roof, as is to be found on the extras list for the SLK. This allows the transparency of the roof to be altered at the touch of a button. And, as an example of just how inventive they can be in Stuttgart, there are the new windscreen wipers for the SL… more magic… ‘Magic Vision Control’. This connotes a unique cleansing technique. No longer is water sprayed on the glass but is ducted through tiny holes in the rubber blades of the windscreen wipers themselves. In a more primitive form this approach was adopted twenty years ago by the Peugeot 405 but Mercedes has refined the system. Now the car’s occupants see no jet of water but nevertheless the glass is visibly cleaned. “The system is so effective that about 50 percent less fluid is actually required”, says Uwe Renz, responsible for the development of this magical feature.
Proven motorizations, low consumption
A significant contribution to fuel economy is claimed by Mercedes… a reduction of up to 30 percent. The motorization options for the new SL will continue to include six-cylinder, eight-cylinder and twelve-cylinder petrol fuelled engines for the simple reason that, according to product manager Bernd Stegman ”worldwide 95 percent of our customers ask for these motors.” This also answers and question concerning diesel power. And in the luxury roadster there will be no hybrid power plant. “We did not want to add back the weight that we took so much pains to eliminate”, Stegman concludes.
