The SL (R107) variant was a 2-seat convertible/roadster with standard soft-top, with optional winter hardtop and only rarely ordered very small rear bench-seat. The SLC (C107) derivative was a 2-door hardtop coupé, on a 36 cm longer wheelbase, and with normally sized rear seats. The SLC was the first and only time that Mercedes-Benz based their S-class coupé on a stretched SL roadster platform, rather than on a large S-class saloon. The SLC replaced the former saloon-based 280/300SE coupé in the Mercedes lineup, while there was no two-door version of the W116. The SLC model run ended in 1981, much earlier than the SL. It was replaced by the considerably larger 380SEC and 500SEC, once again derived from the 1980 S-class line.
Volume production of the first R107 car, the 350SL, started in April 1971 alongside the last of the W113 cars; the 350SLC followed in October. The early 1971 350SL are very rare and were available with an optional 4 speed fluid coupling automatic gearbox. The 1971 4sp auto were quick cars for the day with 0-60 mph in 8 seconds. In addition, the rare 1971 cars were fitted with Bosch electronic fuel injection.
European models and engines
The 350SL and 350SLC for the European market used a 3.5 liter V8 engine. From July 1974 both SL and SLC could also be ordered with a fuel-injected 2.8L straight-6 as 280SL and 280SLC.
Initially all cars had the Bosch D Jetronic fuel injection system, an early electronic engine management system. In December 1975 this was replaced by the Bosch K Jetronic system, an entirely mechanical fuel injection system. This was paralleled with electronic breaker-less ignition and hydraulic valve-lash compensation systems. Performance was mildly reduced to comply with new emission laws.
In September 1977 the 450SLC 5.0 joined the line. This was a homologation version of the big coupé, featuring a new all-aluminium five-liter V8, aluminium alloy bonnet and boot lid, as well as a black rubber rear spoiler and a small front lip spoiler. These changes resulted in a reduction in weight of over 100kg when compared to the 'old' 450SLC. The '5.0' was built in limited numbers, only 2,769 being completed between 1977 and 1981. Maximum speed of the '5.0' was some 10km/h faster than that of the '4.5' at around 225km/h. The 450SLC 5.0 was produced in order to homologate the SLC for the 1978 World Rally Championship.[4]
Starting in 1980, the 350SLC, 450SLC, and 450SLC 5.0 models (like the 350SL and 450SL) were discontinued in 1980 with the introduction of the 380SLC and 500SLC in March 1980. At the same time, the cars received a very mild makeover; the 3-speed automatic was replaced by a four-speed unit, returning to where the R107 started in 1971 with the optional 4 speed automatic 350SL (3.5lt).
The 280SLC, 380SLC, and 500SLC were discontinued in 1981 with the introduction of the W126 series 380SEC and 500SEC coupés. A total of 62,888 SLCs had been manufactured over a ten-year period of which just 1,636 were the 450SLC-5.0 and 1,133 were the 500SLC. Both these models are sought by collectors today. With the exception of the R171 SLK 55 AMG Black Series and the SL65 AMG Black Series, the SLC remains the only fixed roof Mercedes-Benz coupé based on a roadster rather than a saloon.
Following the discontinuation of the SLC in November 1981, the 107 series continued, initially as the 280SL, 380SL, and 500SL. At this time, the V8 engines were re-tuned for greater efficiency, lost a few horsepower and consumed less fuel, largely due to substantially higher (numerically lower) axle ratios that went from 3.27:1 to 2.47:1 for the 380SL and from 2.72:1 to 2.27:1 for the 500SL.
From September 1985 the 280SL was replaced by a new 300SL and the 380SL by a 420SL; the 500SL continued and a 560SL was introduced for certain extra-European markets, notably the USA, Australia, and Japan.
Also in 1985, the Bosch KE Jetronic was fitted. The KE Jetronic system varied from the earlier, all mechanical system by the introduction of a more modern engine management "computer", which controlled idle speed, fuel rate, and air/fuel mixture. The final car of the 18 years running 107 series was a 500SL painted Signal Red, built on 4 August 1989; it currently resides in the Mercedes-Benz museum in Stuttgart, Germany.
North American models
North America was the key market for this Personal luxury car, and two thirds of R107 and C107 production was sold there.[5]
Sales in North America began with the 1972 model year. These early cars wore 350SL badging, but actually had a larger, 4.5-liter V8, coupled to a three-speed automatic - they were renamed 450SL for model year 1973. The big V8 engine became available on other markets with the official introduction of the 450SL/SLC on non-North American markets in March 1973.
R107 and C107 cars were continuously subjected to the ever stringent US emission regulations, with lower compression. At the start the American M117 made a SAE net rating of 192 hp at 4750 rpm and 240 lbft at 3000 rpm; over the years this would continuously plummet, eventually reaching 162 hp at 4200 rpm with 230 lbft at 2500 rpm. The European M117, by comparison, produces 218 PS at 5000 rpm and 360 Nm at 3250 rpm for 1976 through 1980.
The R107/C107 for the North American market sported four round low-output sealed beam headlights, due to unique U.S. regulations. From 1974, the front and rear bumpers were dramatically lengthened, by 8 in on each end, to comply with the U.S. National Highway Traffic Safety Administration regulations that mandated no damage at an impact of 5 mph.[6]
US gray market sales
The more powerful 500SL with a 5.0 liter engine, produced from 1980–1989, was not available in the US. This drove many customers to obtain the European specification car in the "gray market," where the vehicles were converted to meet Federal mandates, until this option was eliminated by Congress in 1988.
From 1986 to 1989, a more powerful version was available from the factory, the 560SL. It was exclusive to the USA, European, Japanese and Australian markets. Despite the larger 5.6 liter engine of the U.S. 560SL, the forbidden Euro-spec 500SL was the fastest production R107 produced (mostly because of the lack of emission reducing components).
The 500SL was published by Mercedes-Benz as having 0-60 mph times of 7.4 seconds for a top speed of 225 km/h. Torque for the 500SL is 296 lbft at 3200 rpm and for the 560SL 287 lbft at 3500 rpm.
Mechanical troubles
Model years 1975 and 1976 for the 450SL suffered from vapor lock and hard restart because of the under-bonnet position of the catalytic converter. Starting in MY 1977, the catalytic converter was moved to replace the resonator, located just behind the transmission in the exhaust system.
The 380SL/SLC engine came with a single row timing chain from 1981 through 1983. These early 380SL/SLC models were plagued with chain failure problems and the problem was corrected by Mercedes-Benz, free of charge (at the time; not honored today). Some vehicles escaped the retrofit and may at some point fail as a result. Model Years ("MYs") 1984 and 1985 came with a double row timing chain from the factory to address this issue.
Another problem area for late 450SLs was the automatic climate control system. Based on a servo which controlled coolant flow to the heater core, as well as vacuum to actuate the vents in the interior of the car, the system proved unreliable. It was installed on 450SLs through end of production in 1980. Models produced prior to 1978 had a manual climate control system, 380SL models produced from 1981 received a more reliable automatic climate control system.
South African assembly
Both the SL and SLC models were also assembled in South Africa by UCDD (United Car and Diesel Distributors) for the captive domestic market from early 1977 (on a contractor basis before Daimler-Benz A.G. acquired a majority stake of UCDD in 1984).[9][10] Only about 40 units per month were built.[9]
AMG Models
AMG offered enhancements for all R107/C107 models, while engine enhancements were not available for the 420 SL.
AMG offered two upgrade tiers for the M117. Tier 1 includes: Combustion chambers and conduits of both cylinder heads were reworked and polished, two AMG camshafts. Tier 1 rose output by 19kW (26HP). Tier 2 includes all of Tier 1 and: Larger valves and camshafts with longer valve timing and more valve stroke along with higher compression combustion chambers rising output 37kW (46HP).
In the first half of the 1980's a few copies of the 500 SL were made equipped with AMG tuned M 117 with 5.2 and 5.4 liter displacements.
AMG options included aerodynamic and appearance elements, limited slip differentials of 3.06, 3.27, and 3.46 ratios, suspension and handling equipment, AMG steering wheels, extended range fuel tanks and rare 5 speed manual transmissions.
Individual vehicles made for special clients include a 350 SLC 6.3, equipped with the M100 and the 450 SLC 6.9 equipped with M100 engine from the W116 450 SEL 6.9. AMG manufactured at least one convertible based on the 450 SLC.
