by Adrian-Liviu Dorofte
e-mail: mercedesbenzblog@gmail.com

Mercedes-Benz-Blog TRIVIA: From "Sport Light" to SL Legend - PART VIII


OFFICIAL PRESS RELEASE

Stuttgart, Germany, Feb 20, 2002

1989: Heart flutter or fascination at its best

* A long history
* Car Design Award
* Torsional rigidity
* High-stability integral seats
* Fully automatic soft-top
* A new suspension
* Twelve-cylinder symphony
* Mercedes-AMG GmbH

The SL legend was continued in Geneva in 1989 with a launch like a thunderbolt when Mercedes-Benz presented a new dream of a car to the world, with numerous world firsts on board: models 300 SL, 300 SL-24 and 500 SL.



No rollover bar marred the fascinating lines of the open roadster – but it was there, raised either at the push of a button or automatically in an accident – a standard feature just like the lightweight aluminum hardtop weighing just 34 kilograms. The car's advanced engineering features also included all-new, sporty integral seats with cast magnesium frame and integrated seat belts, a fully automatic soft-top and a draught-stop for open-top motoring in all comfort. The trunk offered sufficient space for the luggage of two people.

A long history

Development of the R 129 took a long time due to the scrupulous attention given to each individual detail feature. Its history officially began in the early eighties and so it had "time to mature" as one of its creator put it. The Mercedes-Benz designers and engineers invested a lot of time in the fine-tuning of the car's features, thereby succeeding in not just satisfying but by far exceeding the high expectations of customers and interested parties all over the world.

In the course of the decades, the SL face had conquered a firm place in the Mercedes-Benz model hierarchy. The new SL demonstrated a stylistically new interpretation of the traditional radiator grill: within the radiator mask organically integrated in the engine hood, the Mercedes star was complemented by horizontal louvers made of anodized aluminum.

The stylish and smooth lines of the slightly wedge-shaped bodywork, the flared wheelarches for the wide tires, the half-spoilers in front of the front wheels, the steeply inclined windshield, the well-sculpted rear end and the standard light-alloy wheels combined into a vibrant beauty which fascinated not only the friends of the brand.

Aerodynamic fine-tuning extending to the underfloor and the air flow through the engine compartment resulted in a fuel-saving and speed-boosting Cd value of 0.31 for the car with the hardtop fitted – a variable value for a roadster, rising to 0.40 with the soft-top down.

Car Design Award

Less than a year after its launch, the SL received the much-coveted international Car Design Award presented by a jury of eleven journalists from ten countries plus representatives of the city of Turin and the Piedmont region. The jury explained its decision as follows:

'In the Mercedes-Benz 300 – 500 SL, the combination of new safety features, ... exemplary ergonomic solutions and a design fully in keeping with the brand's traditional culture is found to be highly convincing. The new SL thus embodies the most valuable elements of contemporary industrial design – without foregoing the flair every sports cabriolet should have.'

The exemplary solutions included, among other things, the draught-stop, an ingenious combination of tubing and netting that prevented turbulence behind the windshield without interfering with the 'climate' inside the passenger compartment. Leather jackets and caps were therefore just as much a thing of the past as ladies getting wind-blown. Even high speeds no longer presented a draughty problem, and open-top driving at low temperatures proved to be an effective road show. Today the innovative draught-stop – in which its inventors hold four patents – is a matter-of-course element of many cabriolets anywhere in the world.

Torsional rigidity

The car also set new standards in the field of safety. A precondition for perfect functioning of the fully automatic soft-top was the torsional rigidity of the bodywork – and it left nothing to be desired in this respect, either. It did not have to fear comparison with the sedans and became the generally valid yardstick for open-top car rigidity throughout the industry.

The open-top car was subjected to the demanding Mercedes-Benz front and rear impact tests – and the results were sensational, verifying the development engineers' scrupulous work. Bodywork rigidity in a lateral crash by far exceeded the legally required level; this was attributable to the integrated design of all detail features, for instance doors overlapping the sills, cross-bracing under the seats plus rigid propeller shaft tunnel sides, or the high-strength steel tubes inside the A-pillars, enhancing resistance to a roof impact.

Another element of the safety concept was the rollover bar, which was automatically raised from its virtually invisible rest position in the event of a threatening rollover at lightning speed. The potential of this innovative feature and the entire safety package was demonstrated in dramatic form during the trial-driving launch for journalists. Driver and passenger were a bit rattled after their accident but otherwise unscathed.

High-stability integral seats

Ground-breaking features in interior design were the SL's integral seats, representing an engineering masterpiece in their setup and forming a crucial element of the safety concept. The seat frame and backrest were made of different, specifically matched thin-wall magnesium alloy castings. Three-point seat belts, automatically height-adjusting head restraints and the servomotors for longitudinal, height and angle adjustment of seat squab and backrest were all fitted on or inside the seat. Another important element was the automatic locking of the backrest. The seat's load-bearing capacity in a crash amounted to several times the maximum possible forces.

The seat incorporated 20 patents for detail features; in appreciation of his pioneering work, its creator received the 1989 Paul Pietsch Award which comes with a respectable prize amount.

Fully automatic soft-top

The fully automatically opening and closing soft-top was a small miracle in itself – not because of the hydraulic soft-top operating system but because of the complicated folding of the top into the narrow soft-top compartment and the desired taut and smooth fit of the soft-top when closed. It had to be – and was – resistant to the vacuum pressure above the roof on the move, which would otherwise have pulled the soft-top upwards like a balloon, and the rollover bar had to – and did – work perfectly even with the soft-top closed.

A new suspension

The suspension was equally all new. At the front, the wheels were located by a damper strut axle with coil springs, anti-dive control and dual wishbones, gas-pressure shock absorbers and an anti-roll bar. The car was also the first SL with a modified multi-link independent rear suspension with anti-squat and anti-lift control, coil springs, gas-pressure shock absorbers and an anti-roll bar.

Those wishing even more sensitive springing response or even greater tautness for dynamic motoring were able to opt for the adaptive damping system, ADS, that controlled the car's level depending on the load in the car, the road surface and the driving style – the system was the precursor of active suspension.

The brakes convinced even hard-baked test drivers who put the SL to the acid test on the Passo dello Stelvio. The car was decelerated by four-piston fixed-caliper disc brakes on the front axle and twin-piston fixed-caliper disc brakes on the rear axle. The brake discs were internally ventilated both front and rear and ABS was as much fitted as a matter of course as a dual-circuit brake system. Brake Assist (BAS) was incorporated in 1996, the Electronic Stability Program (ESP) minimizing the risk of skidding in 1999.

Twelve-cylinder symphony

The entry-level model into the new SL world was the 300 SL with two-valve six-cylinder engine which developed 190 hp/140 kW; it was followed by the 300 SL-24 with four-valve 231 hp/170 kW engine. These two power units were replaced in 1993 by new four-valve engines with 2.8 and 32. liter displacement, dominating the field until 1998 with both their output of 193 hp/142 kW and 231 hp/ 170 kW, respectively, and their silky-smooth running characteristics.

The next to follow were V6 engines with three-valve technology and dual ignition: a 2.8 liter with 204 hp/150 kW and a 3.2 liter with 224 hp/165 kW. The flagship was initially the 500 SL whose four-valve V8 developed 326 hp/240 kW. Following the revision of model designations, the 500 SL was renamed SL 500 in June 1993 – a designation principle applied to all Mercedes-Benz models.

In October 1992, the dream of many SL friends came true when at last the much longed-for twelve-cylinder was introduced – a six-liter V-engine with four overhead camshafts, four valves per cylinder, adjustable intake camshafts, microprocessor-controlled injection and "high-speed" catalytic converters.

With the SL 600 – designated SL 600 from June 1993 – people acquired an output of 394 hp/290 kW and acceleration from standstill to 100 km/h in 6.1 seconds. Its "little" eight-cylinder brother took 6.5 second and they both effortlessly reached a top speed of 250 kilometers per hour – or would have reached even more had their top speed not been electronically limited.

Mercedes-AMG GmbH

Those demanding even greater performance and prestige from the eight- and twelve-cylinder models were able to turn to the brand's sports branch, Messrs. AMG in Affalterbach near Stuttgart, in which DaimlerChrysler has held a 51 percent stake since January 1, 1999 when it was re-named Mercedes-AMG GmbH. The branch offered customers with an appetite for power several alternatives, for instance, in the late nineties, the SL 55 AMG whose 5.5 liter V8 developed 354 hp/260 kW and completed the sprint from standstill to 100 km/h in 5.9 seconds.

Top-of-the-pops was the SL 73 AMG, whose 7.3 liter V12 produced 525 hp/ 386 kW and catapulted the car to 100 km/h in just 4.8 seconds. Without speed limiter, the car was capable of doing 300 kilometers per hour. The powertrain of the AMG models was matched to the higher loads in all its components, from automatic transmission to rear axle.

The AMG styling package, including fog lamps integrated in the front bumper, emphasized the dynamic appeal of the roadster without interfering with its clean lines. The large, 18" light-alloy AMG wheels added an additional touch of unmistakable sportiness.

At the time of the discontinuation of the R 129, the fourth generation of production SL cars, some 494,000 units of the exclusive sports cars from the SL-Class had come off the assembly lines at the Mercedes-Benz car plants in Sindelfingen and Bremen. This total figure includes just under 205,000 units of the R 129, the first SL generation to be produced in the Bremen plant. It does not include the 26,000 units of the 190 SL, this car being allocated to the market segment of today's SLK-Class.



























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