Mercedes Benz R107 and C107

Model history

The R107 and C107 took the chassis components of the midsize Mercedes-Benz W114 model and mated them initially to the M116 and M117 V8 engines used in the W108, W109 and W111 series.

The SL variant was a 2-seat convertible/roadster with standard soft top and optional hardtop and optional folding seats for the rear bench. The SLC (C107) derivative was a 2-door hardtop coupe with normal rear seats. The SLC is commonly referred to as an 'SL coupe', and this was the first time that Mercedes-Benz had based a coupe on an SL roadster platform rather than on a saloon, replacing the former saloon-based 280/300 SE coupé in Mercedes lineup. The SLC was replaced earlier than the SL, with the model run ending in 1981, with a much larger model, the 380 SEC and 500SEC based on the new S class.

Volume production of the first R107 car, the 350 SL, started in April 1971 alongside the last of the W113 cars; the 350 SLC followed in October. Sales in North America began in 1972, and cars wore the name 350 SL, but had a larger 4.5L V8 (and were renamed 450 SL for model year 1973); the big V8 became available on other markets with the official introduction of the 450 SL/SLC on non-North American markets in March 1973. US cars sold from 1972 through 1975 used the Bosch D Jetronic fuel injection system, an early electronic engine management system.

From July 1974 both SL and SLC could also be ordered with a fuel-injected 2.8L straight-6 as 280 SL and SLC. US models sold from 1976 through 1979 used the Bosch K Jetronic system, an entirely mechanical fuel injection system. All US models used the 4.5 liter engine, and were called 450 SL/SLC.

In September 1977 the 450 SLC 5.0 joined the line. This was a homologation version of the big coupé, featuring a new all-aluminum five-liter V8, aluminum alloy bonnet and boot-lid, and a black rubber rear spoiler, along with a small front-lip spoiler. The 450SLC 5.0 was produced in order to homologate the SLC for the 1978 World Rally Championship.

Starting in 1980, the 350, 450 and 450 SLC 5.0 models (like the 350 and 450 SL) were discontinued in 1980 with the introduction of the 380 and 500 SLC 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.

The 280, 380 and 500 SLC were discontinued in 1981 with the introduction of the W126 series 380 and 500 SEC coupes. A total of 62,888 SLCs had been manufactured over a ten-year period of which just 1,636 were the 450 SLC-5.0 and 1,133 were the 500 SLC. Both these models are sought by collectors today. With the exception of the SL65 AMG Black Series, the SLC remains the only fixed roof Mercedes-Benz coupe based on a roadster rather than a sedan.

Following the discontinuation of the SLC in September 1981, the 107 series continued initially as the 280, 380 and 500 SL. At this time, the V8 engines were re-tuned for greater efficiency, lost a few hp and consumed less fuel- this largely due to substantially higher (numerically lower) axle ratios that went from 3.27:1 to 2.47:1 for the 380 SL and from 2.72:1 to 2.27:1 for the 500 SL.

From September 1985 the 280 SL was replaced by a new 300 SL, and the 380 SL by a 420 SL; the 500 SL continued and a 560 SL was introduced for certain extra-European markets, notably the USA 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 500 SL painted Signal red, built on August 4, 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 2/3 of R107 and C107 production was sold there.

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 inches (203 mm) on each end, to comply with the U.S. National Highway Traffic Safety Administration regulations, that mandated no damage at an impact of 5-mile-per-hour (8 km/h).

R107 and C107 cars were exported to the US with low compression 4.5 liter V8 engines to meet stringent US emissions requirements, yet still provide adequate power. The faster 450SLC 5.0, 500SL, and 500SLC were never sold.

The 450 SL was produced until 1980. Starting in 1980, US cars were equipped with lambda control, which varied the air/fuel mixture based on feedback from an oxygen sensor.

The smaller engined 380 SL replaced the 450SL from 1981 to 1985. The 380 SL was the least powerful of the US imported R107 roadsters.

The more powerful 500 SL with 5.0 liter engine, produced from 1980–1989, was not available in the US. This drove many customers to obtain the car in the "gray market."

Finally, a more powerful version was available from the factory, from 1986 to 1989, the 560 SL. It was exclusive to the USA, Japanese and Australian markets.

Despite the larger 5.6 liter engine of the U.S. 560 SL, the forbidden Euro-spec 500 SL is the fastest production 107 produced (mostly because of the lack of emission restraints). The 500 SL was published by Mercedes-Benz as having 0-60 mph times of 7.4 seconds for a top speed of 225 km/h (140 mph). Torque for the 500 SL is 296 lb·ft (401 N·m) at 3200 rpm and for the 560 SL 287 lb·ft (389 N·m) at 3500 rpm.

Mechanical Troubles

Model years 1975 and 1976 450 SLs suffered from vapor lock and hard restart because of the under-hood 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/C engine came with a single row timing chain from 1981 through 1983. These early 380 models were plagued with chain failure problems and the problem was corrected by Mercedes-Benz, free of charge. Some models, however, escaped retrofit and may at some point fail as a result.

MYs 1984 and 1985 came with a double row timing chain from the factory to address this issue.

Another problem area for late 450 SLs and early 380 SLs 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 450 SLs from 1976 through end of production in 1980, and continued on the 1981 MY of the 380 SL. Models produced prior to 1976 had a manual climate control system, models produced after 1981 received a more reliable automatic climate control system.

South African assembly

Both the SL and SLC models were assembled in South Africa by UCDD (United Car and Diesel Distributors) from early 1977. Only about 40 units per month were built.