A sequential manual transmission, also known as a sequential gearbox, or a sequential transmission, is a type of non-synchronous

manual transmission A manual transmission (MT), also known as manual gearbox, standard transmission (in Canada, the United Kingdom, and the United States), or stick shift (in the United States), is a multi-speed motor vehicle transmission system, where gear changes ...

used mostly for

motorcycle A motorcycle (motorbike, bike, or trike (if three-wheeled)) is a two or three-wheeled motor vehicle steered by a handlebar. Motorcycle design varies greatly to suit a range of different purposes: long-distance travel, commuting, cruising ...

s and

racing cars Auto racing (also known as car racing, motor racing, or automobile racing) is a motorsport involving the racing of automobiles for competition. Auto racing has existed since the invention of the automobile. Races of various sorts were organise ...

. It produces faster

shift time Shift time refers to the time interval between gear changes in a transmission. This interval is the time in which power delivery is transferred to the next selected gear, and engine speed is reduced or increased to synchronize the speed of the n ...

s than traditional synchronized manual transmissions, and restricts the driver to selecting either the next or previous gear, in a successive order.

Design

A sequential manual transmission is unsynchronized, and allows the driver to select either the next gear (e.g. shifting from first gear to second gear) or the previous gear (e.g., shifting from third gear to second gear), operated either via electronic paddle-shifters mounted behind the steering wheel or with a sequential shifter. This restriction avoids accidentally selecting the wrong gear; however, it also prevents the driver from deliberately "skipping" gears. The use of

dog clutch A dog clutch (also known as a positive clutch or dog gears) is a type of clutch that couples two rotating shafts or other rotating components by engagement of interlocking teeth or dogs rather than by friction. The two parts of the clutch are de ...

es (rather than

synchromesh A manual transmission (MT), also known as manual gearbox, standard transmission (in Canada, the United Kingdom, and the United States), or stick shift (in the United States), is a multi-speed motor vehicle transmission system, where gear change ...

) results in faster shift speeds than a conventional manual transmission. On a sequential manual transmission, the shift lever operates a ratchet mechanism that converts the fore-and-aft motion of the shift lever into rotation of a selector drum (sometimes called a barrel) which has three or four tracks machined around its circumference. Selector forks are guided by the tracks, either directly or via selector rods. The tracks deviate around the circumference and as the drum rotates, the selector forks are moved to select the required gear. A sequential manual transmission is not to be confused with a "sequential" shifting function sometimes fitted to hydraulic

automatic transmission An automatic transmission (sometimes abbreviated to auto or AT) is a multi-speed transmission used in internal combustion engine-based motor vehicles that does not require any input from the driver to change forward gears under normal driving co ...

, marketed with terms such as "Tiptronic" or "SportShift". This function allows the driver to select the previous or next gear through the use of buttons or a lever (usually near the gear shifter or steering wheel); however, the mechanicals of the transmission are unrelated to a true sequential manual transmission.

Usage

Most motorcycles use a sequential manual transmission. The rider controls the gear shifter with their foot, allowing their hands to remain on the handlebars, and gear selection uses a layout of ' (for a typical 6-speed gearbox, said as "one down, five up"). However, most modern

motor scooters A scooter (motor scooter) is a motorcycle with an underbone or step-through frame, a seat, and a platform for the rider's feet, emphasizing comfort and fuel economy. Elements of scooter design were present in some of the earliest motorcycle ...

do not use a sequential manual transmission; instead using either a

hydraulic Hydraulics (from Greek: Υδραυλική) is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. At a very basic level, hydraulics is the liquid counter ...

, or a belt-driven or chain-driven continuously variable transmission.

Underbone An underbone is a type of motorcycle that uses structural tube framing with an overlay of plastic or non-structural body panels and contrasts with monocoque or unibody designs where pressed steel serves both as the vehicle's structure and body ...

s, however, often use a

semi-automatic transmission A semi-automatic transmission is a "theoretical" multiple-speed transmission where part of its operation is automated (typically the actuation of the clutch), but the driver's input would be required to launch the vehicle from a standstill and t ...

with an automatic

centrifugal clutch A centrifugal clutch is an automatic clutch that uses centrifugal force to operate. The output shaft is disengaged at low rotational speed and engages more as speed increases. It is often used in mopeds, underbones, lawn mowers, go-karts, chainsaws ...

, but will still retain the conventional foot-operated gearshift lever, such as the

Honda Super Cub The Honda Super Cub or Honda Cub is a Honda underbone motorcycle with a four-stroke single-cylinder engine ranging in displacement from . In continuous manufacture since 1958 with production surpassing 60 million in 2008, 87 million in 2014, an ...

History

The first proper sequential manual gearbox used in a racecar was with the

Porsche Dr. Ing. h.c. F. Porsche AG, usually shortened to Porsche (; see below), is a German automobile manufacturer specializing in high-performance sports cars, SUVs and sedans, headquartered in Stuttgart, Baden-Württemberg, Germany. The company ...

Type 360 Cisitalia in 1946, followed by the infamously unreliable ''

Queerbox The Queerbox was the nickname for an early sequential manual transaxle used by Lotus racing cars of the late-1950s and early-1960s, and was very similar in design and operation to a motorcycle gearbox. It was infamously unreliable. Lotus Twelv ...

'' design, pioneered by Richard Ansdale and

Harry Mundy Harry Mundy (1915–1988) was a British car engine designer and motoring magazine editor. He was educated at King Henry VIII School in Coventry and went on to serve his apprenticeship with Alvis. He left them in 1936 to join English Racing Au ...

, which was used in various Lotus Grand Prix racecars during the late-1950s and early-1960s, beginning with the 1958

Lotus 12 The Lotus 12 was a Formula Two and Formula One racing car. Design Colin Chapman's first foray into single-seater racing, the 12 appeared in 1957. It featured a number of important innovations Chapman would use on later models. To better use the ...

, and is technically the first proper "sequential" gearbox used in a racecar. Most racing cars also use a sequential transmission now (via a sequential shift lever, with a mechanical linkage, or electronic paddle-shifters), rather than the old H-pattern stick shift, beginning with the paddle-shifted Williams FW14

Formula One Formula One (also known as Formula 1 or F1) is the highest class of international racing for open-wheel single-seater formula racing cars sanctioned by the Fédération Internationale de l'Automobile (FIA). The World Drivers' Championship, ...

car in 1991, which used a sequential drum-rotation mechanism. The first modern sequential manual gearbox with a manual shift lever was used in the 1990

Peugeot 905 The Peugeot 905 is a sports-prototype racing car built by Peugeot's racing department, Peugeot Talbot Sport. The car was initially unveiled in February 1990 and was developed throughout 1990 before making its race debut in the final two races of ...

Group C Group C was a category of sports car racing introduced by the FIA in 1982 and continuing until 1993, with ''Group A'' for touring cars and '' Group B'' for GTs. It was designed to replace both Group 5 special production cars (closed top tou ...

sports car A sports car is a car designed with an emphasis on dynamic performance, such as handling, acceleration, top speed, the thrill of driving and racing capability. Sports cars originated in Europe in the early 1900s and are currently produced by ...

, followed by the

Ferrari 333 SP The Ferrari 333 SP is a sports prototype race car that was built by Italian race car manufacturer Dallara and later Michelotto to compete in the World Sports Car championship for Ferrari. Unveiled at the end of 1993, at the behest of amateur ra ...

LMP

racecar Auto racing (also known as car racing, motor racing, or automobile racing) is a motorsport involving the racing of automobiles for competition. Auto racing has existed since the invention of the automobile. Races of various sorts were organise ...

and

CART A cart or dray (Australia and New Zealand) is a vehicle designed for transport, using two wheels and normally pulled by one or a pair of draught animals. A handcart is pulled or pushed by one or more people. It is different from the flatbed tr ...

Champ Cars/

Indycar INDYCAR, LLC, is an American-based auto racing sanctioning body for Indy car racing and other disciplines of open wheel car racing. The organization sanctions five racing series: the premier IndyCar Series with its centerpiece the Indianapolis ...

s in 1994 and 1996, and then the

McLaren F1 GTR The McLaren F1 GTR is the racing variant of the McLaren F1 sports car first produced in 1995 for grand touring style racing, such as the BPR Global GT Series, FIA GT Championship, JGTC, and British GT Championship. It was powered by the na ...

Mercedes-Benz CLK GTR The Mercedes-Benz CLK GTR (C297) is a GT1 sports car built and produced by Mercedes-Benz in conjunction with their then motorsport partner AMG. Intended for racing in the new FIA GT Championship series in 1997, the CLK GTR was designed primar ...

Porsche 911 GT1 The Porsche 911 GT1 is a car designed and developed by German automobile manufacturer Porsche AG to compete in the GT1 class of sportscar racing, which also required a street-legal version for homologation purposes. The limited-production street- ...

, and

Panoz Esperante GTR-1 The Panoz Esperante GTR-1 (also known as Panoz GTR-1 and later the Panoz GTP) was a race car developed by Panoz Auto Development and Reynard Motorsport for grand tourer endurance racing in 1997. Although named after the Panoz Esperante roadste ...

GT1

s in 1996 and 1997. This was closely followed by WRC

Rally car Rally is a wide-ranging form of motorsport with various competitive motoring elements such as speed tests (often called ''rally racing),'' navigation tests, or the ability to reach waypoints or a destination at a prescribed time or average speed. ...

s in 1997, 1998, and 1999, and also the

Porsche LMP1-98 Dr. Ing. h.c. F. Porsche AG, usually shortened to Porsche (; see below), is a German automobile manufacturer specializing in high-performance sports cars, SUVs and sedans, headquartered in Stuttgart, Baden-Württemberg, Germany. The company i ...

Nissan R390 GT1 The Nissan R390 GT1 was a racing car built in Atsugi, Japan. It was designed primarily to gain a suitable racing entry in the 24 Hours of Le Mans in 1997 and 1998. It was built to race under the grand touring style rules, requiring a homologated ...

Toyota GT-One The Toyota GT-One (model code TS020) is a racing car initially developed for grand touring GT1 rules, but later adapted into a Le Mans prototype LMGTP car. It raced in the 1998 and 1999 24 Hours of Le Mans. History Following the end of the ...

, and the BMW V12 LM' and LMR

Le Mans Prototype A Le Mans Prototype (LMP) is the type of sports prototype race car used in the 24 Hours of Le Mans, FIA World Endurance Championship, IMSA SportsCar Championship, European Le Mans Series and Asian Le Mans Series. Le Mans Prototypes were create ...

racecars Auto racing (also known as car racing, motor racing, or automobile racing) is a motorsport involving the racing of automobiles for competition. Auto racing has existed since the invention of the automobile. Races of various sorts were organise ...

in 1998 and 1999.

Touring cars Touring car racing is a motorsport road racing competition with heavily modified road-going cars. It has both similarities to and significant differences from stock car racing, which is popular in the United States. While the cars do not move ...

have also used sequential manual gearboxes; starting with the European DTM series in 2000, which used it for 12 seasons, until a switch to a paddle-shift system in 2012. The Australian V8 Supercars series started using sequential manual gearboxes in 2008, after switching from an H-pattern manual gearbox.

NASCAR The National Association for Stock Car Auto Racing, LLC (NASCAR) is an American auto racing sanctioning and operating company that is best known for stock car racing. The privately owned company was founded by Bill France Sr. in 1948, and hi ...

introduced a 5-speed sequential manual transmission with their '' Gen-7 car'' in 2022, after using a conventional 4-speed H-pattern manual transmission for many years. Due to the high rate of wear and abrupt shifting action, sequential manual transmissions are rarely used in passenger cars, albeit with some exceptions.

References

{{Motorcycle components Automotive transmission technologies Motorcycle transmissions

Design

Usage

History

See also

References