Mercedes-Benz W108/W109

Chassis (platform)

The car's predecessors, the W 111 (1959–71) and W 112 (1961–67), helped Mercedes-Benz develop better sales and achieve economy of scale production, reducing both manufacture time and cost. Throughout the 1950s, Mercedes-Benz had been producing the coachwork 300 S and 300 SL and all but hand-built 300 "Adenauer" (W 189) alongside conveyor assembled Pontons (190, 190 SL and 220) etc. Unifying the entire Mercedes-Benz range into the "fintail" reduced production onto a single automobile platform.

Body design

Fashion trends in the early 1960s changed rapidly. By the time the Paul Bracq-designed 2-door coupé and cabriolet W 111 were launched, the predecessor W 111 sedan's fins lost their chrome trim and sharp appearance. The arrival of the W 113 'Pagoda' coupé and cabriolet in 1963 saw them further buried into the trunk's contour. Finally, they disappeared completely on the 600 (W 100) in 1963.

The evolution of the W 108 began under the leadership of Bracq in 1961 and ended in 1963. Although the fins' departure was the most visible change, the W 108 had a lower body waist line and increased glass area – the windscreen alone was 17% larger than W 111's – prominent enough to be referred to as a "greenhouse". The cars had a 60 mm lower ride and 15 mm wider doors. The result was a visibly newer-looking, sleeker car with an open and spacious interior.[1]

Differences between W 108 and W 109

Originally, the W 108 was seen as a combined successor to the W 111 and the short wheelbase sedans in the W 112 line lacking air suspension.

The W 111 had been a successor to the six-cylinder Ponton models of the mid 1950s; the W 112 derived from it was a stopgap to replace the hand-built body-on-frame 300 "Adenauer" (W 189) state car (built through the spring of 1962) pending the 1963 introduction of the 600 "Grand Mercedes" (W 100; ). In addition to being lavishly decorated with additional chrome trim, the W 112 inherited the alloy block M 189 engine of the W 189, and featured a self-levelling air suspension. A long-wheelbase version was offered from March 1963 through July 1965.

This introduction of two lines (standard and luxury) emerged the W 108 and W 109 models, with the dividing line running between luxury, performance and air suspension. Thus that expensive feature was kept on the long wheelbase W 109 300 SEL, while models from the 300 SEb down retained their steel coil springs and oil-filled shock absorbers.

1965: 250 and 300 series

The initial 1965 product line was the W 108 series' 250 S, 250 SE, and 300 SEb, and only the 300 SEL produced as a W 109. As before, the 300 series were more luxuriously appointed than the 250 series, featuring burled walnut dashboards and power windows along with optional automatic transmission and air conditioning. The W 109 also featured door window frames and a-pillars fully finished with polished metal bright trim.

1968: 280 and 300 series

In 1968 Mercedes-Benz retired the M189 engine in favor of the new 2.8L M130. As a result, the long wheelbase W108 280 SEL and W109 300 SEL (which shared a 2850 mm wheelbase) also ended up sharing the 2.8L engine through the end of production in 1972. Similarly, the M116 V8 powered W108 280 SE/SEL 3.5 and W109 300 SEL 3.5, and the M117 V8 powered W108 280 SE/SEL 4.5 and W109 300 SEL 4.5, shared wheelbases and engines through the end of production in 1972.

Mercedes-Benz refused to name these models 350 SEL and 450 SEL to avoid upsetting the release of the W116 S-Class.

Market introduction

The W 108/W 109 premiered at the Frankfurt Auto Show in 1965. The initial model range consisted of three W 108s (250 S, 250 SE, and 300 SEb) and a sole W 109 (300 SEL). The inline-six engines were carried over from the previous generation with mechanical refinements. The 2.2 L M 180 engine was enlarged to 2.5 L while the fuel-injected 3.0 L M 189 version was carried over from 300 "Adenauer".

250 series

The 250 S[2] was fitted with 2497 cc M 108 engine with 2 compound downdraft carburetors producing 130 PS at 5,400/min. The 250 SE had the same engine as 250 S except for fuel injection system and different engine designation (M 129) with increased engine output of 150 PS at 5,500/min.

300 series

Both 300 SEb and 300 SEL were fitted with 2996 cc M 189 engine.

Market introduction

To coincide with the launch of new cheaper executive, W 114/W 115 "/8" (Stroke Eight); ) models, slotted below MB's W 108 and W 109, the inline six engine range was revised in 1967. The 2.5 L engine was enlarged to 2778 cc and renamed as M 130 for both carburetted 140 PS at 5,200/min and fuel injected 160 PS at 5,500/min versions.

2.8 L I6 models

250 S and 250 SE were renamed as 280 S and 280 SE in November 1967 while 250 S was still offered in some export markets until March 1969. In January 1968, a long wheelbase variation, 280 SEL, was introduced for the first time.

The standard wheelbase 300 SEb was dropped while 300 SEL 2.8 obtained the 2.8 L engine with higher output 170 PS at 5,750/min, replacing the M189 engine.

3.5 L V8 models

Following the strong reception of the limited production 6333 cc M 100 V8-powered 300 SEL 6.3 in 1967, Mercedes-Benz offered the all-new 3.5 L

In-house developing and production

Unusual among mainstream European automakers of the time, Mercedes developed and built their own automatic transmission system, first went into production in 1961.[3]

I6 models

The standard transmission for Europe was a four-speed manual gearbox. As an option a four-speed automatic with fluid coupling was available. For the first series it was the K4A 025; for the second series the more reliable and smoother shifting all new K4C 025 was introduced in May 1969. A five-speed manual gearbox was offered for six-cylinder 2.8 L and 3.0 L engines, though a few customers opted for it.

Big block V8 model

As a pilot the first model of the more reliable and smoother shifting all new four-speed automatic with fluid coupling layout was the