May 21

May 21 Guide: Schwarz Fünf - a Historical & Technical Appraisal of the Mercedes-Benz C197 SLS AMG Black Series

<<<MERCEDES-BENZ PORTAL
<<<SLS AMG BLACK SERIES FOR SALE

BACKGROUND

After an agonising 55 year wait during which various prototypes of potential successors emerged that never made it into production, Mercedes-Benz finally unveiled an heir to its legendary W198 300 SL Gullwing at the Frankfurt Motor Show in September 2009.

The resultant SLS (internal code C197) was Mercedes’ first road car developed exclusively by AMG and also the first three-pointed star product to feature an aluminium chassis. Deliveries of the Gullwing-doored Coupe began in September 2010 and an open top version of the Super Leicht Sport was subsequently unveiled at the Frankfurt Motor Show in September 2011.

For the 2011 racing season, AMG also developed a GT3 racing version.

Mercedes had last gone GT racing with the CLK GTR, CLK LM and CLR LM series which AMG famously used to depose McLaren’s all-conquering F1 GTR and dominate the FIA GT Championships of 1997 and ‘98.

Although the SLS GT3 was created for customer as opposed to works use, it quickly came to be regarded as arguably the best car in its class thanks to Driver and Manufacturer titles in both the 2012 FIA GT World and European Championships along with that year’s ADAC GT Masters title.

To capitalise on this success and further broaden the appeal of the SLS, Mercedes launched a GT3-inspired version of the fixed head C197 Coupe at the Los Angeles Motor Show in November 2012: the SLS AMG Black Series.

The fifth model in AMG’s Black Series line (after the 2006 SLK55, the 2007 CLK63, the 2008 SL65 and the 2011 C63), this latest iteration of the C197 was lighter, sharper and more powerful than either the standard SLS or the GT version which Mercedes debuted at the Paris Motor Show in September 2012. Practically every aspect of the car came in for significant attention in order to create the most driver-focused 21st century Mercedes yet.

Production was limited to 350 units and deliveries began in June 2013.

CHASSIS

For the Black Series, the aluminium spaceframe chassis used by the SLS received some additional elements fashioned from composite materials to include a new CFRP rear panel behind the seats and diagonal underbody bracing.

As usual, an 85-litre fuel tank was installed over the rear axle.

A new lithium-ion battery saved 8kg compared to a conventional item.

The basic double wishbone suspension layout with Sachs coil springs, Bilstein dampers and an anti-roll bar at either end was carried over. As usual, wishbones, steering knuckles and hub carriers were made entirely from forged aluminium.

Where the Black Series differed was in its uprated version of the normally optional AMG Ride Control that automatically adjusted the damping to suit both driving style and road surface and which enabled the driver to manually select one of three different modes: ‘C’ (Comfort), ‘S’ (Sport) and ‘S+’ (Sport Plus).

For the Black Series, the Comfort mode was dropped, the entire configuration was made stiffer for enhanced stability and new coil-over spring retainers enabled adjustment of wheel loads for customised circuit set-ups.

In addition, track was widened at both ends (20mm and 24mm front to rear respectively), new front axle hubs were installed, the front anti-roll bar was adjusted for added grip and reduced roll angle and the speed-sensitive power steering was re-tuned.

The normally optional ceramic composite brake system with 402mm diameter discs up front and 360mm diameter items at the rear was fitted to the Black Series as standard. Four-piston calipers were used all round. Overall, the carbon ceramic upgrade represented a 40% weight saving over steel discs and provided increased stopping power.

Also fitted as standard were the lightweight ten-spoke AMG forged alloy wheels that had to be specified as en expensive upgrade on the base SLS. The fronts were 10 x 19-inches (with 275/35 R19 tyres) and the rears were 12 x 20-inches (on 325/30 R20 tyres). The wheels automatically came with high sheen matt black centres, polished lips and Michelin Pilot Sport Cup 2 tyres.

ENGINE / TRANSMISSION

In the engine bay was the most highly tuned iteration of AMG’s Type M159 naturally aspirated 90° V8 yet seen for road use.

Created specifically for the SLS, the dry-sumped M159 motor featured an aluminium alloy block and heads with continuously variable dual overhead camshafts per bank and four valves per cylinder. For this latest application, the existing 11.3:1 compression ratio was carried over and displacement was kept at 6208cc thanks to a bore and stroke of 102.2mm and 94.6mm respectively. Engine management was once again courtesy of a Bosch ME 9.7 control unit.

To harness some extra horsepower, AMG modified the Black Series engine in a number of ways.

A reworked high-speed valve train got uprated camshafts, revised cam geometry and optimised specially coated racing-style bucket tappets. This enabled maximum engine speed to be increased from 7200rpm to 8000rpm and intake ducting was modified to suit.

The crankshaft assembly received modified oil bores, new bearings, a new oil pump and high-strength screwed connections for the con rods.

The water and oil cooling systems for both the engine and transmission were upgraded.

Another significant Black Series feature was a titanium instead of steel exhaust with unique centre and rear mufflers. This weighed 13kg less than before and produced an even more striking engine note from the two sets of twin chrome tailpipes.

Finally, the engine was supported by gas-filled strut braces to reduce load change reactions.

With 622bhphp on tap at 7400rpm, the Black Series engine was the most powerful normally aspirated V8 available in a production car at the time. For comparison, the base SLS developed 563bhp at 6800rpm.

The peak torque rating was 468lb-ft at 5500rpm compared to 479lb-ft at 4750rpm for the standard model.

Transmission was through an AMG Speedshift DCT seven-speed automatic transaxle connected via a carbonfibre driveshaft. The dual clutch arrangement saw one clutch close while the other opened to ensure minimal loss of torque transmission.

For the Black Series, the transmission was installed 10mm lower than normal and braced against the body by gas-filled struts to avoid stress cycles.

As usual, the driver could choose from one of four alternative drive modes: ‘C’ (Controlled Efficiency), ‘S’ (Sport), ‘S+’ (Sport Plus) and ‘M’ (Manual). In the ‘M’ setting, shifts had to be executed manually by way of two F1-style paddles mounted to the steering column.

Shift times in Sport Plus and Manual modes were made even faster for the Black Series and downshifts became more audible. There was also a new temporary ‘M’ function that, by pressing the up or down shift paddle once in ‘C’, ‘S’ or ‘S+’ modes, enabled the driver to activate Manual mode without having to remove a hand from the steering wheel.

Other equipment specific to the Black Series included a CFRP as opposed to sand-cast magnesium torque tube between the engine and transmission (which saved 13kg) and a lightweight CFRP driveshaft. There was also a new electronic instead of mechanical variable differential lock for the rear axle (which itself adopted a shorter ratio). The standard-fit three-stage ESP system and Race Start launch control function were re-tuned to suit.

BODYWORK

The Black Series’ aggressive new GT3-inspired look saw practically every panel bar the doors and roof come in for significant attention.

A new nosecone assembly featured a primary intake with high gloss black-painted cross-fins and matching star recess. Outboard of these were enlarged air ducts with exposed CFRP eyebrows. Lower down was a new CFRP chin spoiler that also featured larger intakes.

Further up, Mercedes added headlight assemblies with darker shrouds and a CFRP hood complete with GT3-style central air vent that discharged heat from the engine bay and simultaneously increased front end downforce. The supplementary vents located towards the trailing edge of the hood came with twin blades painted high gloss black (as opposed to silver) which matched the exterior mirror finish.

Down each flank, the engine cooling vent behind each front wheel was enlarged and given an exposed CFRP fascia with single instead of twin blade trim. All four fenders were flared to reflect the widened track and deep side sills with exposed CFRP skirts and a large brake cooling duct were added.

At the back, a new CFRP rear bumper assembly featured enormous vertical cooling vents inboard of which was a massive exposed CFRP diffuser with openings for the four exhaust outlets. Darkened tail light shrouds were fitted to match those at the front. An AMG Black Series badge was mounted to the right-hand side of the trunk lid.

In standard trim, the familiar electronic rear spoiler that deployed into the airflow at 120kmh / 75mph was retained.

INTERIOR

Inside, the ultra sporty theme continued thanks to the installation of various special parts and the deletion of some superfluous luxury equipment.

Most noticeably, single-piece racing-style bucket seats with the AMG insignia embossed onto the headrests replaced the standard items saving 15kg.

The seat centres, the bottom of the dash and transmission tunnel sidewalls, the headliner and cockpit pillars, the door panel inserts and steering wheel were all trimmed in alcantara.

The steering wheel received a red 12 o’clock marker, a high gloss black-painted vertical spoke (to match the air vents) and red stitching. Matching red stitching was also used for the new 3D seam along the dash, the seats, the centre console, the door panels and central armrest. Red seatbelts and floormat edging continued the theme.

In standard trim, the SLS Black Series came without a multimedia system and got an exposed carbonfibre blanking panel instead.

Like every SLS, the full width dash incorporated a small instrument binnacle that housed analogue gauges for road and engine speed. In between was a digital read out, above which was a bank of seven LED upshift indicators.

The list of standard equipment included electric windows, electric mirrors, eight airbags, central locking with keyless-go and automatic climate control.

OPTIONS

Officially, Mercedes offered a choice of seven exterior and two interior colour schemes for the SLS Black Series.

Solarbeam Yellow paint was exclusive to this model. Buyers could alternatively choose from Imola Grey, Iridium Silver Metallic, Mystic White, Magno Alanite Grey, Mars Red and Obsidian Black Metallic.

For the interior, monotone black or two-tone black and red was offered (the latter with red dash, centre console and door centre inserts).

In addition to these colours, a few VIP customers were able to specify alternative colour schemes and full leather as opposed to leather / alcantara upholstery.

The most frequently requested Black Series optional extra was an Aerodynamics Package that comprised front CFRP canards and an adjustable carbonfibre rear spoiler mounted on two aluminium pylons (the latter of which replaced the standard retractable rear spoiler).

Other optional extras included wheels with a high-sheen finish for the spoke faces, exposed carbonfibre exterior mirrors, an exposed carbonfibre engine cover, an exposed carbonfibre interior pack, an infotainment system that included a reversing camera, a media interface and a Bang & Olufsen BeoSound audio system with Dolby Digital 5.1, 1000 watt amplifier and eleven loudspeakers.