The car used a heavily-triangulated tube frame (spaceframe) chassis with lightweight panels bolted on — a classic Chapman approach that kept the structure rigid, strong, and light while maintaining the forward weight distribution of the Lotus 16 despite the engine's relocation behind the driver. The car stood just 28 inches (71 cm) high, excluding the windscreen, and weighed 980 lbs (440 kg). The driver sat in a semi-reclining position, a technique pioneered roughly a decade earlier by Gustav Baumm of NSU.
The F1 version was initially powered by a 2,467 cc Coventry Climax FPF four-cylinder DOHC engine inherited from the Grand Prix version of the Lotus 16. For 1960 the FPF was enlarged slightly to 2,497 cc, producing 239 hp (178 kW) at 6,750 rpm from a weight of only 290 lbs (132 kg). New Formula One engine rules in 1961 brought a replacement 1.5-litre Climax FPF Mk.II. The Formula Junior variant used either a 998 cc Cosworth Mk.III or a Downton BMC "A" Series engine of 948 cc, smaller-gauge chassis tubing, and Alfin drum brakes on all four corners.
Transmission was a lightweight sequential manual unit originally developed for the Lotus 12 by Richard Ansdale and Harry Mundy, incorporating a motorcycle-style sequential gearbox. The unit — nicknamed the "Queerbox" or "Gearbox-full of neutrals" for early reliability problems — was improved by Keith Duckworth during work on the Lotus 15 and 16. After Duckworth left to co-found Cosworth in 1958, Mike Costin, who remained with Lotus briefly, adapted the improved gearbox for the Lotus 18, adding dedicated oil scavenge and pressure-feed pumps. A ZF limited-slip differential shared a common magnesium alloy housing with the gearbox to form a transaxle that also provided mounting points for inboard rear brakes. The Formula Junior version used a Renault 4-speed transaxle; an optional VW gearbox with Hewland 4-speed gears allowed gear ratio changes without removing the gearbox.
Front suspension was by double-wishbone arms with outboard coil/damper units and a separate front anti-roll bar — a departure from earlier Chapman designs where the anti-roll bar ends acted as an upper wishbone leg. Rear suspension used upper and lower radius arms with a reversed lower wishbone, with the fixed-length half-shaft acting as the upper link and coil/damper units mounted outboard.
As a stop-gap before successor models arrived, some Lotus 18 chassis were rebodied with Lotus 21 skins to create the interim Lotus 18/21 hybrid. The Lotus 18 was replaced by the Lotus 21 in Formula One and the Lotus 20 in Formula Junior in 1961.
The Lotus 18 handled remarkably well, with its suspension geometry drastically reducing weight transfer and body roll in cornering. It proved faster than any car Grand Prix racing had previously seen, eclipsing even the legendary Auto Unions and being widely copied. A two-seat sports-racer variant was also built as the Lotus 19, known as the Monte Carlo.
The car achieved Lotus' first Formula One victory on 8 April 1960, driven by Innes Ireland in the non-championship Glover Trophy. Six weeks later, on 29 May, came its first World Championship win — albeit entered by privateer Rob Walker, who had leased the car from Chapman. Stirling Moss drove it to a dominant victory at the 1960 Monaco Grand Prix. Moss also won the United States Grand Prix at the end of that season, helping Lotus finish second in the constructors' championship. The Lotus 18 also gave Jim Clark his first Grand Prix start in 1960.
The 1960 Belgian Grand Prix at Spa was notable for two tragedies: Moss was injured in a practice accident in the Rob Walker Lotus 18 that kept him from the race, and Alan Stacey was killed after leaving the track in his Lotus 18, apparently following a bird strike to the face.
In 1961 Moss repeated his Monaco victory, this time defeating the more powerful "sharknose" Ferraris. He then won at the Nürburgring in changeable weather. Innes Ireland added a third win in the United States, again contributing to Lotus finishing second in the constructors' championship in 1961.
This article is based solely on the supplied corpus. No external sources were consulted; claims that could not be substantiated against the corpus were omitted under the drop-the-claim rule.
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