With the recent reveal of the 2021 Mercedes-AMG GT Black Series, we thought now could be a good time to revisit the AMG GT’s legendary predecessor. From our April 1957 situation, right here’s our First Take a look at of the legendary Mercedes-Benz 300 SLR.
Each time Daimler-Benz returns to racing, success is achieved by a single-minded focus of effort and assets, giving the looks of inevitability. The vehicles, which open up new views in design for prime efficiency, are retired to locations within the Daimler-Benz museum at Untertürkheim, and it’s a uncommon event when the chance arises to review a design intimately. Within the case of the well-known World Championship Mercedes-Benz 300 SLR, the veil has been lifted.
Within the spring of 1956, a number of of us sat within the solar outdoors the elegant Schloss Solitude within the hills above Stuttgart, West Germany. Often, the silence was shattered as a protracted, low silver projectile hurtled towards us at 100 miles per hour after which stopped a number of yards away as if restrained by some supernatural drive. No bizarre brakes might ever cease a automotive like that. The gullwing doorways would open up; a passenger, dazed with noise, velocity, and acceleration akin to he had by no means earlier than skilled, would climb out over the excessive facet; one other would step in, and Rudolf Uhlenhaut, director of the Daimler-Benz Experimental Division, would drive off, smiling fortunately, on one other demonstration run.
Watching him go, and listening to the exhaust word as he modified gears up and down within the distance, Arthur Keser (the Daimler-Benz press chief) exclaimed, “Did you ever see anybody so blissful at his work? He’s a toy maker, delighted to search out folks desirous about his newest creation.”
And this was actually probably the most fabulous toy of all, the quickest automotive on the highway anyplace on the earth at this time. Nobody can presumably say how a lot it price, and it’s positively not on the market. It’s the Mercedes-Benz 300 SLR, the factory-raced sports activities automotive that gained the World Championship for Constructors in 1955, with victories within the Mille Miglia, Targa Florio, and Vacationer Trophy. It now has a coupe physique as an alternative of the open two-seater roadster physique and is utilized by Uhlenhaut for quick long-distance motoring.
Not solely is he accountable for improvement of Mercedes racing and sports activities vehicles; he additionally test-drives the racing vehicles, at speeds equal to these of high skilled drivers, to study the important info about automotive habits that the skilled driver so typically can’t categorical. Apart from, as he says, “At 50, you’ll want to hold in observe.”
To trip within the 300 SLR with Uhlenhaut was a revelation: an object lesson in efficiency and methods to use it. He gave the impression to be doing 100 miles per hour wherever there have been a number of hundred yards of clear highway, however he by no means took an opportunity and at all times gave the impression to be driving with nearly exaggerated respect for different site visitors. However methods to categorical such efficiency in phrases which enable comparability with the bizarre vehicles we all know at this time?
Daimler-Benz engineers had evaluated the racing efficiency when it comes to energy and torque, revolutions per minute and equipment ratios, and lap occasions on given circuits, however had by no means performed an bizarre highway take a look at. That began one thing, and some weeks later (by courtesy of the Daimler-Benz administration) I used to be in a position to collaborate with Robert Braunschweig, editor of the Automobil Revue of Switzerland, in placing this priceless automotive via a full 2000-mile highway take a look at. The performances have been measured with the precision gear usually employed for the exams of the Automobil Revue aside from high velocity, which was measured on the Munich-Eching autobahn (specifically closed for us by the German police) and timed by official timekeepers.
The take a look at included probably the most diversified climate and highway situations in Germany, Switzerland, and Italy, and through it we used the automotive precisely as one would for regular enterprise or pleasure motoring, however at common speeds which can be outdoors of regular expertise. It was on no account the primary time we had collaborated on exams of quick vehicles; however the SLR opened up a brand new stratum of expertise, not solely in acceleration and velocity, however in steering, braking, and highway holding and all of the elements which permit excessive efficiency to be employed in security.
Here’s a automotive that, in the precise situations, can contact 180 mph on the highway; a automotive that within the brief house of 550 yards can speed up from O to 100 mph and brake to a standstill once more; a automotive that overtakes different automobiles and is again by itself facet of the highway once more inside 2 seconds; a automotive that’s idling alongside at 120 mph; and a automotive that makes use of lots much less gasoline than many slower automobiles.
The 300 SLR is a thoroughbred, however a tricky one. In our arms it coated lengthy distances at excessive velocity, and it loitered alongside among the many different site visitors within the cities and villages. My first acquaintance with it was driving it from Stuttgart to Munich in a cloudburst. One other day we took it roaring up over Switzerland’s Susten Cross, necks straining to the acceleration, twitching the wheel to carry it on traces of ice and melting snow. We went storming all the way down to Wassen, up via Goschenen to Andermatt, and off over the tough, rocky tracks to the Oberalp Cross. It went in a steady surge of acceleration and braking over the 6,000-foot Lukmanier, then on to Biasca and Bellinzona, and down the autostrada to Monza, the place we spent a blistering scorching day recording acceleration and braking figures. Then again into Switzerland and over the St. Gotthard to Locarno and Ascona via the thick summer season vacationer site visitors.
A single contact on the starter at all times set the engine going, and we by no means had the slightest mechanical hassle. Implausible acceleration, with none hint of wheelspin, permits secure passing in conditions the place you’d by no means usually consider it. Between carefully spaced mountain hairpins, second and third gears will take it flashing up over 70 mph earlier than slowing to a crawl, underneath the motion of its very good brakes, for the following nook.
The gullwing doorways give the coupe a sure resemblance to the inventory 300 SL, however the SLR is decrease and longer, though the wheelbase is barely shorter. Mechanically there may be little in frequent between the 2 vehicles.
The SLR, derived instantly from the Grand Prix single-seaters, is the final of a collection of vehicles conceived by Daimler-Benz technicians, underneath the course of Dr. Nallinger, to safe concurrently full superiority in Grand Prix and sports activities automotive racing, a activity by which they have been extremely profitable.
The physique, panelled in magnesium alloy, offers precedence to the motive force, the passenger having a small, narrower seat. There may be house for a small suitcase behind the seats, however the trunk itself is completely crammed by the large 37.5-gallon tank, the 2 spare wheels, electrical gasoline pump, and gear equipment. As on all racing Mercedes, the steering wheel lifts off for simpler entry to the driving seat, the place you sit with toes extensive aside astride the housing over the clutch and driveshaft. Forward is the lengthy silver hood, and underneath a cowl on the sprint are 5 dials: tachometer (signifies as much as 11,000 rpm), speedometer (signifies as much as 390 km/h or over 240 mph), thermometers for oil and water, and an oil stress gauge.
The change begins the electrical gasoline pump, and a contact on the starter units the engine going with a stupefying noise composed of the clatter of valves and the gasoline injection pump, the whine of gears, and a common indescribable hammer and growth, magnified by the closed coachwork. Ear plugs are compulsory: They scale back the noise however make dialog unattainable. Nevertheless, an unlimited muffler held on the precise facet of the automotive (which must be remembered when passing) reduces the noise for outsiders (and police) to a satisfying authorized growl.
The one particular instruction concerning driving strategies was a request to keep away from slipping the clutch, and the primary getaway on the town is kind of a second for a brand new driver, already bemused by the noise. In reality, the preliminary acceleration just isn’t staggeringly quick, however because the torque develops, the automotive bounds forward, urgent driver and passengers exhausting towards the backrests. It’s at about 35 mph in first gear that most torque is felt, giving the automotive an acceleration approaching 0.5 g and subjecting the occupants to a sensation that’s the reverse of regular braking.
The load, with two folks and take a look at gear on board, was 2,787 kilos, of which 60 p.c, or 1,670 kilos, was on the rear wheels. The utmost acceleration doable earlier than wheelspin units in is a perform of the friction between tires and the highway and the proportion of weight on the driving wheels. Figures quoted for the coefficient of friction range, however on dry concrete akin to we had, it was most likely between 0.7 and 0.8. The theoretical most acceleration can subsequently be positioned at round 15.5 toes per second per second, however in observe an additional switch of weight onto the rear wheels happens due to the acceleration itself, which momentarily will increase the chances. In reality, with the 300 SLR in first gear, the recorder confirmed a median acceleration of 14.6 toes per second per second between 20 and 40 mph. At one stage, an acceleration of 15.Zero toes per second per second was recorded, and the typical from a standstill to 50 mph corresponds to 14.1 toes per second per second. The outcomes given by the SLR are thus near one of the best that’s theoretically doable with a automotive having two driving wheels.
In regular highway driving, first gear just isn’t employed. The automotive begins simply in second, and in third gear it goes over 100 mph with out reaching the restrict of 8,000 rpm, which will be utilized for brief durations. It’s a uncommon cat in which you’ll go from Zero to 100 mph with out utilizing greater than two of the 5 ratios within the gearbox! Throughout our exams, a restrict of seven,500 rpm was usually noticed, which gave the next most speeds on the gears: first, 50 mph; second, 77 mph; third, 95 mph; fourth, 127 mph; and fifth, 165 mph. For the utmost velocity exams, the place we needed to know absolutely the most the automotive might attain with the perfect gearing for the job, the gearing was modified, entailing a slight sacrifice in acceleration.
The engine is remarkably versatile, and there’s no must shift repeatedly when not attempting for optimum outcomes. But when absolute optimum efficiency is the article, it’s time to consider downshifting from fifth to fourth gear when the velocity drops to 100 mph. This places most torque on faucet, prepared to take advantage of the slightest alternative to take the automotive up from 100 to 120 mph in 5.Eight seconds!
The gearshift, with its brief, stiff lever between the seats, is fantastically quick and exact, regardless of a sophisticated set of interlocking stops that make the gate appear like a mix lock. First gear, ahead on the left, is reached by miserable the button on the shift lever knob. Reverse, reverse to it, is obtained by lifting up a guard on the gate. Second is again within the heart, and third is ahead within the heart. One other sliding guard routinely closes the right-hand slot on the gate and prevents the lever passing throughout into fourth or fifth till third gear has been engaged.
If the acceleration figures surpass something recorded in any earlier highway take a look at, the braking outcomes are equally excellent. The unerring wheel grip, and people huge chassis-mounted inboard brakes, with their turbo cooling fins, will be clapped on exhausting even at 100 mph or extra with out the slightest drama, and in repeated exams, the Tapley meter goes on recording 100 p.c effectivity as if it have been one thing fairly regular. The fifth-wheel and Hasler recorder enabled us to translate the outcomes into distances and common decelerations. For regular braking a light-weight stress is sufficient, however for optimum outcomes the stress is pretty heavy regardless of the hydraulic servo, fed by a gearbox-driven oil pump; this can be a situation to be anticipated with anti-fade racing linings. And we actually tried to make these brakes fade, accelerating exhausting to 50 or 60 mph between carefully spaced hairpins whereas descending mountain passes, however after half an hour or extra of this sort of remedy the brakes would at all times produce a swift straight-line panic cease and not using a hint of seize or fade.
Steering is a bit of disconcerting at first. It’s mild and direct (2.5 turns from lock to lock). It follows the slightest actions of the motive force and transmits some highway shock at low speeds, however at excessive speeds the automotive nearly appears to sense the needs of the motive force, even at 100 mph in driving rain with a gale of wind blowing throughout the highway.
The ZF differential, coupled with a minute examine of suspension and weight distribution, produces an astonishing resistance to wheelspin. It’s exhausting to make the tail break free even when slamming the throttle down in a low gear with the entrance wheels locked over. If one of many wheels hits a moist spot throughout exhausting acceleration, the differential takes maintain instantly; and the automotive goes forward with out the slightest hesitation. At speeds round 180 mph on the autobahn at Munich, the automotive was as straightforward to deal with as a 300 SL at 154, which we had timed on the identical stretch a yr earlier than. The devices have been extraordinarily correct, and the speedometer had solely a 2 p.c error at 180 mph.
On sharp, sluggish corners, particularly on gravel surfaces, the self-locking differential and the focus of weight on the driving wheels assist to supply an inclination for the entrance finish to run extensive if the throttle is used too vigorously. The method is to brake early, go gently on the apex of the flip, after which use full acceleration away from the nook.
To make use of the wonderful capabilities of the SLR on slender, winding and crowded European roads, you should be in good bodily form with fast reactions and good eyesight. You additionally want a specific amount of bodily endurance: the noise (and in summer season, the warmth), the continual focus, and the endless acceleration, braking, and equipment shifting (for this can be a automotive on which one by no means appears to be touring at a gentle velocity) all add as much as a good quantity of effort. However keep in mind that that is merely a racing mannequin, solely partially tailored for highway use.
At low speeds on tough roads, the suspension is difficult sufficient to set one glancing up apprehensively towards the roof: Because the velocity rises it turns into a lot smoother, however the trip by no means sacrifices management to consolation.
With observe, the big energy of the 300 SLR proves to be absolutely usable. On highways, 100 to 120 mph turns into cruising velocity, and on bizarre roads the typical speeds beat something one had thought doable, with out ever taking dangers. To drive such a automotive is to glimpse the qualities of the manufacturing fashions of the distant future. It factors the best way to huge enhancements in controllability and secure dealing with that may make current conceptions out of date. Given a corresponding advance in highway design, we’re clearly a good distance from the bounds of efficiency that might be utilized in security by future motorists.
Engine: OHV inline-eight. Bore 3.07 in. (78 mm). Stroke 3.07 in. (78 mm). Stroke/bore ratio 1.0:1. Compression ratio 9:1. Displacement 181.61 cu. in. (2,976cc). Max. bhp 296 @ 7,450 rpm. Bhp per cu. in. 1.630. Piston velocity @ max. bhp 3734 ft. per min. Max. bmep 189.33psi. Max. torque 228 lb-ft @ 5,950 rpm.
Gas: Gasoline. 90 octane analysis, 83 octane motor.
Engine Building: Two blocks of 4 cylinders, Silumin Gamma aluminum alloy castings. Chromium-plated bores. Curler bearing major, connecting rod, and wrist pin bearings. Desmodromic valves with two cam lobes per valve. Valve clearance taken up by engine compression. Two camshafts per block; one every for consumption and exhaust. Direct gasoline injection by German Bosch system. Dry sump lubrication with full-flow oil filter. Two spark plugs per cylinder, with Bosch twin-magneto ignition. Strain cooling system with thermostat however no fan.
Driveline: Energy taken from gear in heart of crankshaft; ratio 1.0606:1. Single-plate dry clutch in unit with engine. Two-piece hole driveshaft. 5-speed and reverse (all oblique) transmission behind rear axle, with Porsche servo-ring synchromesh on high 4 gears. Alternate gear ratios obtainable. ZF limited-slip differential with varied ring, pinion, and switch gear ratios. Gear ratio combos chosen to go well with a specific race circuit.
Take a look at Ratios (Total gear ratios utilized in MotorTrend exams): Highway use and acceleration exams: 1st, 12.4:1; 2nd, 8:00:1; third, 6.53:1; 4th, 4.89:1; fifth 3.81:1. Prime velocity runs: 1st, 8.62: 2nd, 6:95:1; third, 5.77:1; 4th, 4.32:1; fifth, 3.48:1.
Chassis and Suspension: Welded tubular house body. Unbiased entrance suspension by double A-frames, torsion bar springing, and anti-roll bar. Unbiased rear suspension by low pivot swing axle, longitudinal wheel location by Watt linkages, torsion bar springing. Fichtel and Sachs telescopic shock absorbers on all wheels, finned on rear solely. Inboard hydraulic brakes, radially finned and shrouded aluminum drums, parallel-moving non-servo-acting sneakers. Servo enhance pump pushed off transmission. Complete brake lining space: 294.5 sq. inches. Mechanical hand brake on rear wheels. Gas tank in rear with 40 to 54 gallon capability. Knock-off wire wheels.
Tires: Entrance, 6.00×16; rear, 7.00×16.
Dimensions: Wheelbase, 93.Three inches; entrance tread, 52.Three inches; rear tread, 54.Three inches; size, 171.25 inches; width, 68.9 inches; top, 43.5 inches: floor clearance at lowest level, 6.2 inches.
Steering: Curb-to-curb turning circle, 39.25 toes (left) and 38.75 toes (proper).
Weight: Dry and in racing trim, 1,965 kilos (53% entrance, 47% rear); dry and as examined with spare wheels and different highway gear, 2,176 kilos (48% entrance, 52% rear); with fuel, oil and water, 2,457 kilos (44% entrance, 56% rear); as examined with crew of two and take a look at devices, 2,787 kilos (40% entrance, 60% rear).