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Lotus 18
The Lotus 18 was a race car designed by Colin Chapman for use by Lotus in Formula One, Formula Two, and Formula Junior, which was used from 1960 until 1966 in F1.
Lotus 18 was the first mid-engined car built by Lotus and was a marked improvement over Chapman's early and only moderately successful front-engined formula cars, the 12 and 16. It was introduced for the 1960 F1, F2 and FJ seasons, with about 27 examples of the F1 and F2 versions and 110 of the FJ versions. As a stop-gap before the introduction of the 18's successor models, the Lotus 20 for F2/FJ and 21 for F1, some 18 chassis were rebodied with 21 skins to create the interim Lotus 18/21 hybrid derivative.
The 18 was replaced by the Lotus 21 in Formula One and the Lotus 20 in Formula Junior in 1961.
The car was a classic Chapman design, being extremely light and simple; the body was made up of lightweight panels bolted to heavily-triangulated tube frame (spaceframe) chassis. Thus the car was rigid, strong and light, maintaining the 16's forward weight distribution despite the engine moving behind the driver.
It was powered initially by a 2,467 cc Coventry Climax FPF (3.70" x 3.50") four cylinder DOHC engine inherited from the Grand Prix version of Lotus 16. In 1960, the FPF was enlarged slightly to 2497 cc (3.70" x 90 mm), which produced 239 hp (178 kW) at 6,750 rpm from a weight of only 290 lbs (132 kg) and had a wide torque range.
The 2.5 litre engine was replaced by a 1.5 Litre (82 mm x 71 mm) Climax FPF Mk.II with new Formula One engine rules in 1961. The Formula Junior variant used a 998 cc Cosworth Mk.III or a Downton BMC "A" Series with 948cc displacement. The Formula Junior version also used smaller gauge chassis tubing and Alfin drum brakes on all four corners.
Further contributing to the weight advantage was the adoption of lightweight sequential manual transmission originally developed for Lotus 12 by Richard Ansdale and Harry Mundy incorporating the unique sequential-shifting motorcycle gearbox, and a ZF limited-slip differential in a common Magnesium alloy housing to form a transaxle, which also provided the mounting points for inboard rear brakes. This gearbox had been improved in its reliability for Lotus 15 and 16 in 1957-58 by Keith Duckworth, who had just joined Lotus as a gearbox engineer.
Although Porsche in Austria pioneered the sequential-shifting gearbox for racing cars, with the Type 360 Cisitalia, the idea was relatively new and the original transaxle in the Lotus 12, which was essentially an enlarged motorcycle gearbox, combined with ZF limited-slip differential, had gained the nickname "Queerbox", or "Gearbox-full of neutrals" for its poor reliability. With Duckworth having left to form Cosworth in 1958, Mike Costin, who, despite being the co-founder of Cosworth, remained with Lotus for a while longer, adopted the improved Queerbox in the Lotus 16, into a configuration for directly mounting it behind the engine for Lotus 18 with dedicated oil scavenge and pressure feed pumps, further improving its reliability while retaining the small and light design.
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Lotus 18
The Lotus 18 was a race car designed by Colin Chapman for use by Lotus in Formula One, Formula Two, and Formula Junior, which was used from 1960 until 1966 in F1.
Lotus 18 was the first mid-engined car built by Lotus and was a marked improvement over Chapman's early and only moderately successful front-engined formula cars, the 12 and 16. It was introduced for the 1960 F1, F2 and FJ seasons, with about 27 examples of the F1 and F2 versions and 110 of the FJ versions. As a stop-gap before the introduction of the 18's successor models, the Lotus 20 for F2/FJ and 21 for F1, some 18 chassis were rebodied with 21 skins to create the interim Lotus 18/21 hybrid derivative.
The 18 was replaced by the Lotus 21 in Formula One and the Lotus 20 in Formula Junior in 1961.
The car was a classic Chapman design, being extremely light and simple; the body was made up of lightweight panels bolted to heavily-triangulated tube frame (spaceframe) chassis. Thus the car was rigid, strong and light, maintaining the 16's forward weight distribution despite the engine moving behind the driver.
It was powered initially by a 2,467 cc Coventry Climax FPF (3.70" x 3.50") four cylinder DOHC engine inherited from the Grand Prix version of Lotus 16. In 1960, the FPF was enlarged slightly to 2497 cc (3.70" x 90 mm), which produced 239 hp (178 kW) at 6,750 rpm from a weight of only 290 lbs (132 kg) and had a wide torque range.
The 2.5 litre engine was replaced by a 1.5 Litre (82 mm x 71 mm) Climax FPF Mk.II with new Formula One engine rules in 1961. The Formula Junior variant used a 998 cc Cosworth Mk.III or a Downton BMC "A" Series with 948cc displacement. The Formula Junior version also used smaller gauge chassis tubing and Alfin drum brakes on all four corners.
Further contributing to the weight advantage was the adoption of lightweight sequential manual transmission originally developed for Lotus 12 by Richard Ansdale and Harry Mundy incorporating the unique sequential-shifting motorcycle gearbox, and a ZF limited-slip differential in a common Magnesium alloy housing to form a transaxle, which also provided the mounting points for inboard rear brakes. This gearbox had been improved in its reliability for Lotus 15 and 16 in 1957-58 by Keith Duckworth, who had just joined Lotus as a gearbox engineer.
Although Porsche in Austria pioneered the sequential-shifting gearbox for racing cars, with the Type 360 Cisitalia, the idea was relatively new and the original transaxle in the Lotus 12, which was essentially an enlarged motorcycle gearbox, combined with ZF limited-slip differential, had gained the nickname "Queerbox", or "Gearbox-full of neutrals" for its poor reliability. With Duckworth having left to form Cosworth in 1958, Mike Costin, who, despite being the co-founder of Cosworth, remained with Lotus for a while longer, adopted the improved Queerbox in the Lotus 16, into a configuration for directly mounting it behind the engine for Lotus 18 with dedicated oil scavenge and pressure feed pumps, further improving its reliability while retaining the small and light design.