ROAD TESTS FROM THE SIXTIES
Mercedes-Benz 230SL

Germany

MERCEDES-BENZ 230-SL

Stuttgart's new middle-sized SL replaces both the 190-SL and the 300-SL. Neither as hot as the latter nor as cool as the former, it's a highly refined piece of GT machinery

There's something about a Mercedes-Benz. Something about any Mercedes-Benz, regardless of size or purpose, which telegraphs-through all the senses-the fact that it is a Mercedes-Benz and nothing else. If the body of the 230-SL were completely disguised, anyone familiar with Mercedes-Benz products would instantly recognize it as a member of the family the minute he drove it away. From the sound of the exhaust. From the feel and position of the seat and controls. Even from the smell of the grease, the leather, the paint. We're not sure how they do it, but we're damn sure they do.

One by one, each basic model in the Mercedes-Benz line has been upgraded. The first to receive the treatment was the six-cylinder sedan group, then the four-cylinder sedan group, and now-after years of speculation-a new sports model. Rumor had it that the new car would be an addition to the sports-car line-up, a cut above the 190-SL (September '58 C/D), but along with the 230SL's unveiling at the Geneva Show came word that the 190-SL and the 300-SL-oldest cars in the MercedesBenz stable-have been discontinued.

After a little reflection, this makes good sense. What purpose would be served in continuing or revamping the older SLs when the 230-SL-falling in an untapped median area between the two-has a wider appeal than both of its predecessors combined? The 230-SL might even steal some sales from the 220-SE coupe (August '62 C/D), a posh boulevard job much in vogue with the wealthy just now.

Yet the 230-SL is closer in design concept to the 190-SL and the 220-SE coupe (which provide the running gear and engine, respectively) than to the 300-SL, a car which was originally spawned as an out-and-out competition machine; the 230-SL is much longer on creature comfort and an image of status rather than sport.

As may be seen in the comparison chart, all. the SL-series cars have a 94.5-inch wheelbase and the 230-SL is really as "wide-track" as its looks-the front track is four inches wider than that of the 300-SL. The S in SL, by the way, means Super; the L means Leicht (light, as in weight) and the E in 220-SE means Einspritz, an onomatopoetic word for fuel injection. We'll go along with the S; the 230-SL has a bored-out and souped-up version of the already-warm six-cylinder 220-SE engine. Compared with the 190-SL's four-cylinder engine, the 230-SL delivers 50 more bhp at a weight penalty-for the whole car-of only 55 pounds. But we can't help feeling that a 170-bhp car that weighs over 2,800 pounds hardly merits the designation Leicht.

The 230-SL engine is quite a nice piece of work. The bore is only .079 inches more than the 220-SE's, but the extra 36 bhp comes from more than an increase of 111 cc. The cylinder head is completely new, with a higher compression ratio (9.3 vs. 8.7) and larger valves in addition to a slightly modified camshaft. Instead of the two-plunger Bosch injection pump of the 220-SE with its three distribution units, the Bosch pump on the 230-SL has six separate plungers and individual pipes direct to each injector. Unlike the Mercedes/ Bosch system used on the 220-SE engine, injection does not take place in the intake manifold; the nozzles are screwed into the cylinder head itself, emerging quite close to the valve. This method pre-heats the mixture as it passes through the head and takes advantage of the turbulence occurring in the intake port to obtain complete and rapid vaporization.
By way of further comparison, the 190-SL has the much-maligned double Solex 44-PHH side-draft carburetors and the 300-SL has a Bosch injection system with the nozzles screwed directly into the cylinder walls' where they are shrouded by the pistons at TDC. The earliest 300-SL prototypes had Solex carbs and the straight-eight (actually, double-four) M-196 engines, as used in the 300-SLR and Grand Prix cars, had direct Bosch injection with either curved or straight plenum chambers, the so-called "ram" tubes.

The ram-tube configuration for the 230-SL was determined after typically Teutonic, exhaustive experimentation with tubes of differing diameters, angles and lengths. Rudolf Uhlenhaut, the man responsible for such developments, feels that the moderate length of the 230-SL ram tubes is the optimum compromise between low-end torque and top-end power, with little room for improvement either way. The acceleration figures, falling between those of the 220-SE coupe and the 300-SL, bear him out and, for our part, we discovered that the car will accelerate smoothly in any gear but top from 500 rpm to well beyond the red-line, making a tachometer a categorical imperative in this car. Luckily, it's standard equipment.

The mixture and strength of the incoming fuel charge is controlled by a governor connected to the throttle and sensors of engine speed, intake air pressure and water temperature. There is no choke per se, but as in most road-going fuel-injection systems, there is an automatic cold-start and warm-up enricher.
Along with development of fuel injection, Engineer Uhlenhaut devoted a great deal of time and attention to the exhaust valves. As a result of another almost endless series of tests, Uhlenhaut formulated a number of theories which, in his opinion, pertain to all high performance engines.
Applying Uhlenhaut's findings to the 230-SL engine, Mercedes-Benz came up with the following: the exhaust valves are sodium-cooled and made from an alloy high in nickel content, the stems are chrome-plated and the guides are of bronze to aid heat dispersal, the seats are "armored" and an automatic device rotates the valve in relation to its seat every time it is opened. Wow!

In common with all Mercedes-Benz passenger-car engines since 1951, the in-line valves are operated by a single overhead camshaft with a finger interposed between the valve and the cam lobe. This provides a mini
mum of friction, weight and noise throughout the speed range. In the 230-SL, the intake-valve diameter is 1.47 inches and the lift is .245 inches.

The cylinder head is light alloy while the block remains cast iron, as on the 220 series engines. The large and complex injected engine completely fills the front bay of the 230-SL, but is located far enough forward that it does not intrude upon the foot-room of the passenger compartment.

The car's cornering power is unusually high, but, with a nose-heavy weight distribution (52.5% on the front wheels) and a "sticky" rear suspension, there is quite a bit of built-in understeer which Mercedes-Benz likes to think of as a safety factor: if you close the throttle in the middle of a turn, there is a smooth transition to what feels like a neutral steering condition. It's all very stable-you simply steer your way around the turn until you feel like applying power again.

Somewhat surprisingly, opening the throttle wide in a turn will increase the understeer, though not to the extent that the front end plows. Steering with the throttle, i.e., utilizing the variable slip-angles of the Continental Radial tires, thus becomes a highly practicable cornering method, obviating the necessity for anything as Wagnerian as a four-wheel drift.

As the center of gravity of the 230-SL is located about 16.5 inches above the ground, the front anti-sway bar does not have to work terribly hard at keeping the car level in corners. The driver, in fact, feels no roll at all, but spectators do note a definite lean.

The front roll center is only 4.82 inches above ground level, while the low-pivot, single-joint swing axle rear end. (pioneered by Mercedes-Benz in 1951) has its roll center at 8.45 inches. There is no anti-sway bar at the rear, as the Mercedes-Benz system has much the same roll stiffness as a normal rigid-axle layout. In addition to the coil springs taking vertical loads from the rear axles, there is an auxiliary horizontal coil spring behind the differential carrier coupled to both axle halves which resists large vertical axle movements while allowing a lower roll couple-the same effect Porsche achieves with a transverse "camber compensator" leaf spring.
Wheel travel is normal for a sports-touring car; in compression, the front springs allow 4.55 inches and the rear springs 4.10 inches. On rebound, front wheel travel is 3.75 inches and the rear wheels 5.25 inches. The normal rear-wheel camber setting is slightly negative; it is only on severe rebound that the camber becomes positive enough to materially affect the 230-SL's handling characteristics.

The steering box is the recirculating-ball type; the linkage has the well-known Mercedes-Benz shock absorber which reduces or eliminates road shock transmitted to the steering wheel. As on the 220-SE, some muscular effort is required for hairpin turns and parking maneuvers. For the not-so-sporty, there is a power steering option. Don't sneer; this is the same praiseworthy item we noted in our road test of the 300-SE which always retains feel of the road and requires purposeful effort-not like the overpowered versions so prevalent over here. True, there is less feed-back than with manual steering, but there's enough to give the driver a pretty fair idea of how much "tiger" he is unleashing on the corner.

The power steering has a slightly quicker ratio (three vs. three-and-a-half turns lock to lock), so you have to alter your methods when going from one system to another. With manual steering, you normally set the car up for the corner with a fast flick of the wheel, to over come the initial understeer. With the power assist, you begin as early, but put less lock on the wheels at first then more and more as you go deeper into the turn and ease off lock just as leisurely at the apex.

Some years back there was a big row when a well known and well-fixed sports-car driver-patron tried to order a Mercedes-Benz with a floor shift (not, of course, an SL model). He was informed, as he was escorted from the M-B showroom, that Mercedes-Benz did not consider a floor shift proper attire for a touring car. At some point since, Mercedes-Benz got the message; now both the 220-SE coupe and the 230-SL have "four on the floor;" a lovely, all-synchromesh transmission which has only two counts against it. One-though the placing of the shift lever is ideal, the shift itself is a little vague in its gate, just as all German floor shifts of recent years have been. Two-the ratios are a mixed bag indeed.

First gear (4.42) is very short and runs the engine out of revs at 30 mph; it is only the marvelous flexibility of the engine that prevents a dying gasp as second gear (2.28) is engaged. The drop from second to third (1.53) is well spaced, but while third is good to over 80 mph, there is an annoying gap between it and fourth. Mercedes-Benz might argue that a close-ratio gearbox isn't necessary with an engine of the 230-SL's low-speed pulling power (though the torque doesn't peak till 4,500 rpm) but we would counter that it is precisely because of such an engine that a close-ratio gearbox is at its best -sporty, fun and easier on the powerplant and drive train-if not on the clutch.

There is an automatic-transmission option for the 230-SL; the same well-designed, well-built unit described in the December '61 mag, featuring a hydraulic coupling and a four-speed planetary gearbox of light weight and compact dimension (just three inches longer and 30 pounds heavier than the manual transmission). It, too, is controlled by a floor-mounted lever, moving through a staggered quadrant (2-3-4-0-R-P, reading front to rear). By using the stick to hold the engine to the red-line (5,600 rpm) in each gear, the acceleration is almost as good as with the manual transmission and the difference in top speed is only three mph (121 vs.
124). The ratios are unchanged from those of the 300-SE (or the 220 and 190 series, for which this transmission has now been made optional), with a 3.98 first gear, a 2.52 second, a 1.52 third and direct fourth. Obviously inspired by the GM HydraMatic, the Daimler-Benz transmission has a hydraulic coupling (no torque converter) and two sets of planetary gears-one for third, one for second, with first gear as the compound of both. The axle ratio is the same for both manual and automatic transmissions: 3.75 to one.

In designing the body for the 230-SL, Dr. Wilfert has succeeded in creating a modern "sports" car which does not cling too closely to the precepts laid down by Pininfarina and Michelotti, who virtually dictate body design all over Europe and England. The lines are crisp and clean and lend themselves well to good space utilization.

A carry-over from the 190-SL is a bulge in the center of the hood, presumably connoting power below. The 230-SL engine, as in the 190-SL, stands bolt upright (unlike the 300-SL engine, which is laid over at a 50° angle-occasioning two power bulges) . The photos show the Lichteinheit (literally, "light unity") headlamps cum-signal light system which originated on the 300-SL when it was changed from a gull-wing coupe to a roadster. For the U.S., 230-SLs will have the requisite compromises with Lichteinheit to ensconce all that candlepower in legal enclosures.

At the rear, the spare tire rides nearly vertically, halfsubmerged in a deep well to the left of the gas tank. This gets it out of the way of the baggage, but the well protrudes so far below the floor line of the monocoque structure that it determines the ground clear:ance, being the lowest point on the car body. If the trunk is shallow, it is at least wide, and stretches all the way forward to the shock-absorber mountings, enclosing 11.8 cu ft.

The angular body lines arouse very little wind noise (except when' a window is open) and directional stability is never a problem; the 230-SL seems even less sensitive to crosswinds than the Gibraltar-steady 220SE coupe.

In standard form, the 230-SL is a convertible, with a detachable hard top available as optional equipment. The hard top fastens easily with small locking levers at each corner; it may be fitted while the soft top is folded behind the passenger compartment. An optional transverse seat may be inserted in the space between the top well and the two front seats.

The driver's and passenger's seats are true buckets, giving full lateral support not only around the thighs and hips but also right up the back to shoulder height. They are set lower than in any previous MercedesBenz, but are no less luxurious than those, say, of the 220-SE coupe. The seat bottoms are sufficiently deep and well padded to accommodate the most commodious or sensitive derrieres. More than ample adjustment is provided both for seat-back angle and for fore-and-aft positioning. The foot pedals are conveniently large and offer lots of space in between and on the left (clutch foot) side. One option most likely to be seen in conjunction with the automatic transmission is a full width bench seat in front. Normally the seats are covered with a rugged leatherette; genuine leather upholstery is another extra-cost option.
'The hip line of the car is low, which, with the low seating position, gives an excellent all-around view. According to the factory, the window area of the 230SL is 38% greater than on the 190-SL, which one glance at the aptly-named "greenhouse" will verify. The huge rear window of the hard top gives a virtually unrestricted view for parking and merging. The flattop windshieid is designed to give the driver a panoramic view of anything out in front-or overhead (hanging traffic lights and the like).

The steering wheel is placed suitably low and at a more nearly vertical angle than in the sedans. The other controls have benefited from thoughtful design, the hand brake, for example, is placed on the floor close by the transmission hump, common practice on Italian and English sports cars. On the left side of the steering column is a new multi-purpose lever with a rubber knob at the end. It works the turn signals in the normal fashion-up to turn right and down to turn left. Pushing the rubber knob tighter on the lever switches the wipers on, and a separate two-speed switch is built into the knob. The lever also works on the back-and-forth plane-pushing operates the windshield washer and pulling it back flashes the headlights.

In the 230-SL, the normal Mercedes vent panes are replaced by fresh-air ducts on the dash and below, at knee level. The heating system works by mixing hot and cold air, while ventilation is accomplished by exhausting stale air through the headliner material to openings above the rear window.

There are spacious door pockets, a glove compartment illuminated by a map-reading light, and an ash tray in a console between the two seats. A day-night rear-view mirror inside is supplemented by the standard side mirror, and the passenger door-pull doubles as a grab rail.

There is much ado about safety, mostly in the form of padding (steering-wheel hub and sun visors-which swivel to cover either the 'windshield or the side windows). The door locks are separate from the inside handles and anchorage points for seat belts are standard, though not the belts themselves.

The 230-SL has Girling discs at the front and Alfin drums at the rear, assisted by an Ate hydraulic booster. Ate, by the way, is the German licensee for Lockeed - a competitor of Girling - but the miscegeny works well enough to stop the car as quick as you want, every time. Which is all that could be asked of it. Safety fast prevails here, too: a twin master cylinder layout is used, even the fluid reservoirs are separated.

What hath Mercedes wrought? By filling in a gap while lopping off the extremities, class distinction among owners of its sports cars has been abolished. With a sweep of the three-pointed star, Mercedes-Benz has saddened the hearts of the Great Unwashed who coveted 190-SLs, and of nonplussed Carriage Trade owners of 300-SLs who may well look for something more prestigious than the 230-SL, come trade-in time.

The business end of the 230-SL is aimed straight at the heart-and purse-of the new rich living the sweet life; those who hanker for something sporty, with a "cruising" speed in excess of 100 mph and no stinting on comforts or appointments; who are ready, willing and eager to pay for it.

Of such as these, there are many-in the U.S., Germany, Italy and even such improbable venues as Vientiane, the capital of Laos, where the magic of the name Mercedes-Benz has risen to wholly unforeseen heights: shiny new 220-SE sedans are conspicuously displayed in the living rooms of their proud Laotian owners.

Warning: If you (and your bank) can't afford a 230-SL, don't give in to the temptation to "just" test drive one-you'll get such a craving for it as to make Tantalus look like a Brahman achieving Nirvana.

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other seventies road tests:

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Author: ArchitectPage

PRICE: Approx. $8,000 P.O.E.
OPERATING SCHEDULE:
Fuel recommended Premium
Mileage. . . . . . . . . . . . . . . . . . . . . . . . . .. 16.24 mpg
Range on 17.2 gallon tauk 275-410 miles
Crankcase capacity 5Y. quarts
Change at intervals of 3,800 miles
Number of grease fittings 20
Most frequent maintenance.Oil change, lubrication and regular maintenance (factory chart C) at 3,800 miles
ENGINE:
Displacement . . . . . . . . .. . .. .. . . .. . . . .141 cu in. 2,306 cc
Dimensions. . . . . . . . . . . . . . . . . . . . . .6 cyl, 3.23-in bore, 2.87-in stroke
Valve gear Single overhead camshaft with finger followers
Compression ratio 9.3 to one
Power (SAE) .170 bhp @ 5,600 rpm
Torque. . . . . . . . . . . . . . . . . . . . . . . .159 lb-ft @ 4,500 rpm
Usable range of engine speeds 500-6,500 rpm
Carburetion. . . . . . Daimler-Benz/Bosch fuel-injection system
CHASSIS:
Wheelbase. . . . .. . . . . . . . . . .94.5 in
Track. . . . . . . . . . . . . . . . F 58.5 in, R 58.5 in
Length. .. . . . . . . . . . . . . . . . . . . . . . . . . .168.7 in
Ground Clearance. . . . . . . . . . . . .5.4 in

Suspension: F: ind., wishbones and coil springs, anti. roll bar
R: ind.. single-joint low-pivot swing axles, coil springs and
auxiliary transverse coil spring
Steering. . . . . . . . . . . . . . Recirculating ball
Turns, lock to lock 31/.
Turning circle diameter between curbs. . . . . .33 Y. ft
Tire size. . . . . . . . . . . . . . . . . . . . . . . . . .185 x 14
Pressures recommended. . . . . . . . . . . . F 24, R 24 psi
Brakes. .10-in Girliug discs front, 9-in Alfin drums rear, 351 sq in
swept area .
Curb weight (full tank) . . . . . . . .. . . . .2,855 lbs
Percentage on the driving wheels. . . . . . . . . . . . .47.5
DRIVE TRAIN:
Clutch. . . . . . . . . . . . . .. Single dry plate

Gear Synchro Ratio Step Over- Mph per 1.000 rpm
Rev No 3.92 - 14.68 -5.0
1st Yes 4.42 94 % 16.60 4.5
2nd Yes 2.28 49% 8.58 8.7
3rd Yes 1.53 53% 5.72 12.9
4th Yes 1.00 - 3.75 19.7
Final drive ratio. . . . . . . . . . . . .3.75 to one
ACCELERATION:
Zero to
30 mph . 3.1

40 mph .. 5.0

50 mph .. 6.9

60 mph .. .. 9.9

70 mph . .12.0

80 mph . . .15.0

90 mph . . .18.9

100 mph ..22.0

Standing1/4 -mile. . .. .. . . . . .. 17.0 Seconds