Guide: Mercedes-Benz W194 300 SL
Background
Mercedes and Benz enjoyed significant success as separate firms during motor racing’s early days.
Their merger in 1926 created an industrial behemoth.
When Adolf Hitler’s Nazi party came to power in 1933, substantial government funds were diverted to both Mercedes-Benz and rival Grand Prix manufacturer, Auto Union.
The result was absolute domination of the sport from 1934 until the outbreak of World War 2; Germany’s nationalistic approach left conventionally funded Italian, French, British and American teams unable to compete on equal terms.
Six years after hostilities ended, Mercedes executives agreed the firm should return to top flight motor racing.
The decision was made in June 1951. However, as the new two-litre un-supercharged Formula 1 regulations did not reflect the firm’s technical aspirations, a sports car programme for the 1952 season was sanctioned instead.
Since 1947, Ferrari had established itself as the dominant force in this class of racing.
In addition to the red cars from Maranello, Mercedes’ big budget machine would be pitched against an exceptional field of new models from Jaguar, Aston Martin and Alfa Romeo plus specialist firms like Gordini, Cunningham and Allard.
Given type number W194, the new 300 SL (Sport Leicht) used an array of mechanical parts sourced from the W186 300-series that had been introduced in April 1951.
Chassis
At its core was a brand new tubular steel spaceframe that weighed just 70kg.
Distinctive Gullwing doors were required for the neat aluminium body because of two large bulkheads that ran down each flank. The bulkheads provided extra torsional rigidity, but resulted in very high sills, hence the need for Gullwing as opposed to conventional doors.
The 300 SL had a wheelbase of 2400mm. Front track was narrower than the back (1381mm and 1445mm respectively).
By canting the engine at a 50° angle, Mercedes were able to give the car a very low profile and exceptional aerodynamic efficiency.
Front suspension was via unequal length wishbones while the rear swing axle was imported from the W186.
Coil sprung telescopic dampers were fitted all round along with finned hydraulic drum brakes.
The 5 x 15-inch Rudge centre lock wheels were originally shod with Englebert and later Continental tyres.
A huge fuel tank was located behind the rear axle. How full it was had a major impact on handling.
Furthermore, the rear swing axle was joined only at the differential and not the wheels themselves which led to potentially extreme changes in camber on imperfect road surfaces.
Engine / Gearbox
The Type M194 single overhead camshaft Straight 6 engine fitted to the SL was a modified version of the standard W186 300-series unit.
As per the original, it featured a cast-iron block, light aluminium alloy two valve head and displaced 2996cc thanks to a bore and stroke of 85mm and 88mm respectively.
Because the engine was canted at 50°, the spark plugs had to be repositioned from the block to the cylinder head.
The SL engine also featured a high lift camshaft and three Solex downdraught carburettors.
Compression was increased from 6.4:1 on the standard W186 unit to 8.0:1.
Peak output was 175bhp at 5200rpm and 207lb-ft at 4600rpm.
Early examples used wet-sump lubrication to save weight, but this was soon changed to a racier dry-sump arrangement.
Mercedes’ existing W186 four-speed gearbox was installed, but uprated with a separate oil pump.
Bodywork
Bodywork was designed and fabricated in-house at the Sindelfingen works with the exception of the first two prototypes that were manufactured at Unterturkheim.
The lightweight fully enveloped bodywork was typical of early 1950s German design. It featured soft curves, short overhangs and little in the way of superfluous decoration.
Exposed headlights were mounted either side of a primary nose intake complete with 15-bar grille and three-pointed star.
Surprisingly, engine cooling vents were absent from both the hood and flanks.
To improve aerodynamics, the cockpit was made as narrow as possible. Visibility was excellent thanks to the slim pillars.
Interior
Once over the wide sills, the driver was confronted with a wood-rimmed four-spoke steering wheel and body coloured metal dash.
Dials for road and engine speed were housed in separate cowls directly behind the steering wheel.
Supplementary gauges for oil pressure, oil temperature, water temperature and fuel were mounted alongside the steering column.
A clock was positioned in the centre of the dash along with a variety of toggle switches.
Aside from two cloth bucket seats with tartan-patterned centres, there was no upholstery to speak of.
Weight / Performance
Although performance figures were never published, the 1130kg Gullwing was estimated to have a top speed of around 155mph.
Depending on the axle ratio, a 0-62mph time of around 5.5 seconds would most likely have been possible.
Production
Of the ten W194s originally built, nine were completed with closed Gullwing bodywork and one was a Spyder.
At least three of the Gullwings were subsequently transformed to Spyders mid-season.
Mercedes’ first prototype was running by November 1951.
In March 1952, the finished W194 was shown to the press.
1952 Mille Miglia
The new model made its competition debut on May 4th 1952 when a trio of silver Gullwings were entered for the Mille Miglia. They were allocated to Hermann Lang / Erwin Grupp (chassis 003), Karl Kling / Hans Klenk (004) and Rudolf Caracciola / Paul Kurrle (005).
Chief opposition came from Scuderia Ferrari who were backed by a legion of privateers, most notably Scuderia Marzotto which ran a five-car prancing horse team.
Jaguar and Aston Martin had both brought cars over from England, although the latter would contest the GT class with their DB2s.
Kling set a fast pace from the off. He took the lead when Giovanni Bracco / Alfonso Rolfo Ferrrai 250 Sport suffered early tyre trouble. The Ferraris of Eugenio Castelotti and Piero Taruffi then applied some pressure, however, in the wet conditions, Kling was able to average nearly 93mph and retain his position at the head of the field.
By the time he reached Florence, Kling had a four minute lead over the hard-chasing Bracco. By this time, Lang had crashed out in one of the sister Mercedes. Caracciola had been delayed while stuck behind the Aston Martin DB2 of George Abecassis.
Meanwhile, Bracco was driving superbly and eventually forged ahead in the Futa Pass. More tyre trouble soon after the Bologna checkpoint allowed Kling back through, but Bracco had re-taken the lead and had established a 100 second advantage by the time he reached Modena.
This was subsequently extended when Kling / Klenk were forced to make a late stop for a loose wheel.
Bracco / Alfonso ultimately won by 4 minutes and 32 seconds. Kling / Klenk claimed second and Luigi Faglioli / Vincenzo Borghi were third, 26 minutes down the road in their Lancia Aurelia B20.
Caracciola / Kurrle took fourth for Mercedes in what had been a promising first outing for the new SL.
1952 Swiss GP Support Race, Bremgarten
Two weeks later, the Swiss Formula 1 Grand Prix at Bern hosted the Prix de Bremgarten for Sports cars.
Four Gullwings were entered for the 18 lap race. Three had been used on the Mille Miglia.
The cars arrived in Switzerland having been repainted powder blue (003: Hermann Lang), green (004: Karl Kling) and dark red (005: Rudolf Caracciola). A new silver Gullwing (006) was entered for Fritz Riess.
Fastest in qualifying was the works Ferrari 340 America of Swiss Sportscar Champion, Willie Daetwyler. The big Ferrari was followed by the Mercedes of Kling, Caracciola and Lang. The factory Aston Martin DB2s and Lancia Aurelias were next. Fritz Reiss started eleventh in his previously unraced SL.
Once the pole-starting Ferrari had retired (after just three laps), Mercedes were able to take a dominant 1-2-3 finish with Kling, Lang and Riess placing first, second and third respectively.
Fastest lap went to Hermann Lang.
Unfortunately, the race was marred by a career-ending crash that left Rudolf Caracciola severely injured. On lap 13, Caracciola had lost control and his dark red Mercedes ploughed headlong into a tree at high speed.
Although Caracciola never raced again, chassis 05 was rebuilt and went on to appear at the Carrera Panamericana in November.
1952 Le Mans 24 Hours
Three new Gullwings were entered for the 1952 Le Mans 24 Hours which took place over the weekend of June 14th and 15th.
All three cars were painted silver and featured newly extended doors that cut into the sides of the bodywork.
Chassis 007 was allocated to Hermann Lang / Fritz Riess (blue noseband) and 008 to Karl Kling / Hans Klenk (green noseband). In the absence of Rudolf Caracciola and Luigi Faglioli (both injured) chassis 009 was entered for Theo Helfrich and Helmut Niedermayr (red noseband).
A spare car (006, painted plain silver) was also taken to la Sarthe. During practice, this vehicle periodically ran with an experimental roof-mounted airbrake. However, the airbrake was deemed unsafe by the organisers and removed on safety grounds.
During the build-up to the race, Lang set the fastest unofficial speed down the Mulsanne Straight (150mph) and also the fastest practice lap with a time just one tenth-of-a-second quicker than Alberto Ascari’s works Ferrari 250 Sport.
Grid positions were dictated by engine size which meant the Mercedes lined up ninth (Helfrich / Niedermayr), tenth (Lang / Riess) and eleventh (Kling / Klenk).
The race got underway in sunny conditions at 4pm. Phil Walters initially led in his Cunningham followed by Stirling Moss in a Jaguar C-type. However, by lap two the Ferraris of Andre Simon and Alberto Ascari had taken over at the head of the field.
The two Ferraris exchanged new lap records until Ascari came into the pits with clutch trouble on lap six. Simon then continued to draw away from the chasing pack.
Meanwhile, the Mercedes began to close the gap to the lead bunch.
After two hours, the best placed Mercedes were those of Helfrich in fifth and Kling in sixth.
During the fourth hour, Lang moved into second spot behind the Gordini T15S of Robert Manzon while Pierre Levegh began to up his pace in the third-placed Talbot-Lago T26 GS. An hour later, Levegh had demoted Lang to third.
Lang remained in third position until just after midnight when a wire came adrift which caused the car to short circuit and retire.
A couple of hours later, the lead Gordini retired which promoted Levegh’s Talbot-Lago into the lead.
At 4am, Levegh had a substantial advantage over the second-placed Helfrich / Niedermayr Mercedes while Lang / Riess were just behind in third.
With one hour to go, it seemed that Levegh was set for a famous victory. He had driven single-handedly for 23 hours, but the fairytale win was not to be; the Talbot-Lago broke a con-rod near Maison Blanche and was eliminated.
This left the two Mercedes firmly in the lead. They were circumspectly driven to the finish and crossed the line almost together with Lang / Riess a lap ahead of Helfich / Niedermayr.
Rounding out the podium was the special-bodied works Nash-Healey of Leslie Johnson and Tommy Wisdom that finished 15 laps down the road.
1952 German GP Support Race, Nurburgring
Another Formula 1 support race was held for Sports cars at the 1952 German Grand Prix on August 3rd.
Mercedes sent a team of four cars to the Nurburgring, all of which appeared with new Spyder bodywork.
One was a brand new Spyder (010) while the other three cars had all been converted from Gullwing trim. Chassis 006 appeared with green flashes, 007 with blue flashes and 009 with red flashes). The new car (chassis 010 with black flashes) had been built on a shorter 2200mm wheelbase chassis.
All four Spyders ran a new side-exiting exhaust system that emerged from a cut-out on the right-hand sill.
Also present and trialled during practice was a supercharged engine in a fifth Spyder (dubbed the 300 SLK). A Roots-type blower drew and then compressed the fuel from three sidedraught carburettors mounted directly onto the casing.
Kling had already trialled the supercharged engined at the Nurburgring in July. Peak output was 230bhp, but the Type M197 Kompressor motor was not used in the race.
Opposition to the Silver Arrows was limited.
Kling took pole for the 10 lap race in the short wheelbase car. Lang was second, Robert Manzon’s works Gordini T15S was third, Riess was fourth and Helfrich fifth. Vaino Holding qualified his Jaguar XK120 sixth and further back were a couple of privateer Ferraris.
When the flag dropped, the four Mercedes streaked into the lead chased by Manzon’s Gordini. However, when Manzon retired with a broken gear lever, the race turned into a Mercedes benefit.
After 10 laps and nearly two hours behind the wheel, Lang took the win and also posted fastest lap in 007. Kling was second in the short wheelbase chassis 010, Riess was third in 009 and Helfrich placed fourth in 006.
1952 Carrera Panamericana
After a glittering season of success, the 300 SLs were wheeled out for one final event and the most lucrative on the calendar: the Carrera Panamericana.
The 1952 Carrera took place from November 19th to the 23rd and was opened up to Sports cars having previously been organised exclusively for series production machinery.
Mercedes took three silver cars for the gruelling 1934-mile event: Gullwing chassis 005 for Hermann Lang / Erwin Grupp (blue flashes), Gullwing 008 for Karl Kling / Hans Klenk (green flashes) and Spyder chassis 009 for John Fitch / Eugen Geiger (white flashes).
All three cars were sponsored by Mexican Mercedes-Benz agent, Prat Motors SA, and ran bored out 3.1-litre engines.
Chief opposition was expected to come from 1951 winners, Ferrari, who sent a trio of new 340 Mexicos which had been developed specially for this event. The Ferraris had uprated 280bhp engines and a narrow track to increase their top speed. Also present as part of the works Ferrari squad was the Mille Miglia-winning 250 Sport.
The works Gordini team attended with a pair of their venerable T15S models and a trio of factory-supported Lancia Aurelias were also in attendance.
Stage one (a 329 mile route from Tuxtla Gutierrez to Oaxaca) saw the Mercedes of Kling initially forge ahead chased by Giovanni Bracco’s Ferrari and Jean Behra’s Gordini. Unfortunately, Robert Manzon retired his Gordini from the event with mechanical problems after just 25 miles while Bracco’s team-mate, Luigi Villoresi, lost considerable time with gearbox trouble.
Shortly afterwards, the works Ferrari of Alberto Ascari crashed and was too heavily damaged to continue. The supercharged Lancia of Felice Bonetto was another early casualty.
Behra’s Gordini won the stage by a margin of four minutes over Bracco and nine over Kling. Kling’s progress had been slowed after he hit a buzzard at 135mph which smashed through the windscreen and briefly knocked navigator Hans Klenk unconscious. The next day, each Gullwing emerged with eight protective bars fixed in place over the windscreen to prevent the re-occurrence of such an incident.
Day two got underway with a 256 mile stage from Oaxaco to Puebla; the mountainous route was among the most perilous on the event.
In his ultra-light Gordini, Behra revelled in the arduous conditions until, with Puebla almost in sight, he left the road at a sharp hairpin and tumbled into a ditch.
Having been delayed on the first stage, Villoresi charged back up the leaderboard to win the stage by two-and-a-half minutes from Fitch in the 300 SL Spyder. Kling’s Gullwing was another minute-and-a-half behind in third.
Although eclipsed on the stage, Bracco inherited the lead in the general classification.
Stage two was marred by a fatal accident when the Jaguar XK120 driven by Santos Letona crashed into the parapet of a bridge near Puebla. Letona was killed instantly and his co-driver was seriously hurt.
Later the same day, a short 83 mile stage took the cars from Puebla into Mexico City. Villoresi was quickest again followed by Bracco who extended his overall lead. Mercedes drivers Kling and Fitch were third and fourth respectively.
The third day’s racing encompassed two stages.
The first was a 267 mile dash from Mexico City to Leon where Villoresi continued his rapid progress up the leaderboard to win by four minutes from team-mate Bracco. Luigi Chinetti’s Ferrari was third.
Bracco by now had a nine-minute lead over second-placed Kling in the general classification. Kling’s team-mates Fitch and Lang were third and fourth, Chinetti was fifth and Villoresi had by this time recovered to sixth.
Stage five was a 333 mile route from Leon to Durango, after which the competitors would be able to enjoy a rest day.
Unfortunately, the dash into Durango saw Villoresi’s clutch expire and he was out of the event.
Instead, it was Kling’s Mercedes that won the stage, gaining over a minute on Bracco.
However, Mercedes had their share of trouble too; Fitch arrived late having suffered suspension and tyre trouble.
After the rest day at Durango, Kling won the 251 mile stage into Parral. Bracco still had a seven-minute lead, but he was nursing his Ferrari along which allowed Lang and Chinetti to take second and third on the stage.
By stage seven (186 miles from Parral to Chihuahua), the mountains had long since given way to vast prairie lands. Long straight roads permitted the fastest cars to hit speeds in excess of 150mph.
Kling won his third stage in succession (at an average of 126mph). Chinetti’s Ferrari was second, Maglioli’s Lancia third and Lang’s Mercedes fourth.
Stage seven marked the end of Giovanni Bracco’s great effort when his transmission finally gave up. Thus, Kling inherited the lead in the general classification with Lang promoted to second and Chinetti third.
The final leg was a 230 miles section from Chihuahua to the finish in Ciudad Juarez on the US border. Driving his 300 SL Spyder, Fitch crossed the line ten seconds ahead of team-mate Kling. Two-and-a-half minutes later came Chinetti’s Ferrari by the Mercedes of Lang which was another 60 seconds in arrears.
Unfortunately, a short time later Fitch was disqualified from the event for having received outside assistance; a mechanic had reputedly touched his car on the penultimate stage.
The result meant that Kling / Klenk took the overall victory with a time just over 35 minutes faster than their team-mates Lang / Grupp in the sister Gullwing. Luigi Chinetti / Jean Lucas claimed third sport in their Ferrari 340 Mexico.
Post Season
Thereafter, although tentative plans were made for a 1953 campaign, the W194s were retired from competition duty as Mercedes decided to focus on their W196 Formula 1 programme for 1954.
After the green light was given for a production version of the 300 SL in early 1953, an eleventh W194 Gullwing was manufactured and used for development purposes (chassis 011).
Text copyright: Supercar Nostalgia
Photo copyright: Mercedes-Benz - https://www.mercedes-benz.com
