Torsen Torque-Sensing (full name Torsen traction) is a type of

limited-slip differential A limited-slip differential (LSD) is a type of differential that allows its two output shafts to rotate at different speeds but limits the maximum difference between the two shafts. Limited-slip differentials are often known by the generic tr ...

used in

automobile A car or automobile is a motor vehicle with wheels. Most definitions of ''cars'' say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people instead of goods. The year 1886 is regarded ...

s. It was invented by American Vernon Gleasman and manufactured by the

Gleason Corporation Gleason Corporation is a prominent machine tool builder based in Rochester, New York, USA. It has manufacturing plants in the USA, Britain, India, China, Switzerland and Germany, and sales offices in those and additional countries. Gleason's import ...

. Torsen is a

portmanteau A portmanteau word, or portmanteau (, ) is a blend of wordstrademark A trademark (also written trade mark or trade-mark) is a type of intellectual property consisting of a recognizable sign, design, or expression that identifies products or services from a particular source and distinguishes them from oth ...

s of JTEKT Torsen North America Inc (formerly Zexel Corporation, formerly Gleason Power Systems). All Torsen differentials have their origin in the Dual-Drive Differential that was invented and patented by Gleasman in 1958.

Use

Torsen differentials can be used in one or more positions on a

motor vehicle A motor vehicle, also known as motorized vehicle or automotive vehicle, is a self-propelled land vehicle, commonly wheeled, that does not operate on rails (such as trains or trams) and is used for the transportation of people or cargo. The ...

: * center—used to apportion

torque In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment of force (also abbreviated to moment). It represents the capability of a force to produce change in the rotational motion of t ...

appropriately between front and rear axles on an

all-wheel drive An all-wheel drive vehicle (AWD vehicle) is one with a powertrain capable of providing power to all its wheels, whether full-time or on-demand. The most common forms of all-wheel drive are: ;1x1 : All unicycles Reflecting one axle with one ...

vehicle. * rear—used to apportion torque appropriately between left and right sides in rear axles. This may be on either a

rear-wheel drive Rear-wheel drive (RWD) is a form of engine and transmission layout used in motor vehicles, in which the engine drives the rear wheels only. Until the late 20th century, rear-wheel drive was the most common configuration for cars. Most rear-wheel ...

or a four-wheel drive vehicle. * front—used to apportion torque appropriately between left and right sides in front axles. This may be on either a

front-wheel drive Front-wheel drive (FWD) is a form of engine and transmission layout used in motor vehicles, where the engine drives the front wheels only. Most modern front-wheel drive vehicles feature a transverse engine, rather than the conventional longi ...

or a four-wheel drive vehicle. A four-wheel-drive vehicle, for example, may use one, two, or three Torsen differentials.

Types

, there are three types of Torsen differentials. # The original ''Torsen T-1 (Type A)'' uses crossed axis helical gears to limit torque split. The Type I can be designed for higher torque bias ratios than the Type II, but typically has higher backlash and the potential for noise, vibration, and harshness (NVH) issues, and requires a precise setup/installation. # The later ''Torsen T-2 (Type B)'' uses a parallel gear arrangement to achieve a similar effect. There is also a specialist application of the T-2, known as the ''T-2R (RaceMaster)''. # The latest ''Torsen T-3 (Type C)'' is a planetary type differential, in that the nominal torque split is not 50:50. The Type C is available as single or twin version; the Torsen twin C differential has front and center differential in the same unit. The Torsen T-3 is currently employed as the center differential in all non- Haldex Traction

Audi Audi AG () is a German automotive manufacturer of luxury vehicles headquartered in Ingolstadt, Bavaria, Germany. As a subsidiary of its parent company, the Volkswagen Group, Audi produces vehicles in nine production facilities worldwide. The o ...

models with a ZF-sourced automatic transmission

Quattro Quattro is Italian for the number four. Quattro may also refer to: People * "Quattro", a nickname of A. J. Foyt IV Fictional characters * Quattro Vageena or Quattro Bageena, an alias of Char Aznable in the ''Mobile Suit Gundam'' anime series ...

four-wheel drive Four-wheel drive, also called 4×4 ("four by four") or 4WD, refers to a two-axled vehicle drivetrain capable of providing torque to all of its wheels simultaneously. It may be full-time or on-demand, and is typically linked via a transfer ca ...

, such as:

Audi A6 The Audi A6 is an executive car made by the German automotive industry, automaker Audi. Now in its fifth generation, the successor to the Audi 100 is manufactured in Neckarsulm, Germany, and is available in saloon and Station wagon, estate configu ...

, Audi A7, and Audi Q7. Audi uses a mechanical "Crown Wheel" center differential for all longitudinal implementations using dual-clutch transmissions, such as the 2013/14 S4/RS4.

Alfa Romeo Alfa Romeo Automobiles S.p.A. () is an Italian luxury car manufacturer and a subsidiary of Stellantis. The company was founded on 24 June 1910, in Milan, Italy. "Alfa" is an acronym of its founding name, "Anonima Lombarda Fabbrica Automobili." ...

used a Torsen C twin differential in the Alfa Romeo 156 Crosswagon Q4 and also in the

159 Year 159 (CLIX) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time in Roman territories, it was known as the Year of the Consulship of Quintillus and Priscus (or, less frequently, year ...

Alfa Romeo Brera and Spider The Alfa Romeo Brera and the Alfa Romeo Spider (Type 939) are mid-size sports cars using the GM/Fiat Premium platform, manufactured by Pininfarina and marketed by Alfa Romeo as a 2+2 coupé and roadster respectively. 12,488 units of the Spider ...

Q4 models. Also,

Toyota is a Japanese multinational automotive manufacturer headquartered in Toyota City, Aichi, Japan. It was founded by Kiichiro Toyoda and incorporated on . Toyota is one of the largest automobile manufacturers in the world, producing about 10 ...

uses a Torsen T-3 in the center differential of the 4Runner Limited, FJ Cruiser 6-speed manual, Land Cruiser, Land Cruiser Prado and Lexus GX470, with manual locking feature, and General Motors used a Torsen T-3 center differential in the transfer case of the

Chevrolet TrailBlazer SS The Chevrolet TrailBlazer is a mid-size SUV produced by Chevrolet, a division of General Motors. The nameplate was first used in North America from 2001 to 2008; in 2009 it was replaced by the Traverse, as a crossover SUV. In 2011, a produ ...

and Saab 9-7X (Aero model only).

Behaviour of Torsen differentials

The Torsen differential works just like a conventional differential, but can lock up if a torque imbalance occurs, the maximum ratio of torque imbalance being defined by the torque bias ratio (TBR). When a Torsen has a 3:1 TBR, that means that one side of the differential can handle up to while the other side would have to only handle of applied torque. During acceleration under asymmetric traction conditions, so long as the higher traction side can handle the higher applied torque, no relative wheelspin will occur. When the traction difference exceeds the TBR, the slower output side of the differential receives the tractive torque of the faster wheel multiplied by the TBR; any extra torque remaining from applied torque contributes to the angular acceleration of the faster output side of the differential. The TBR should not be confused with the uneven torque-split feature in the planetary-type Torsen III. The planetary gearset allows a Torsen III center differential to distribute torque unevenly between front and rear axles during normal (full traction) operation without inducing wind-up in the drivetrain. This feature is independent of the torque bias ratio.

Torsens in front and/or rear axles

When a vehicle is in a turn, the outer wheel will rotate faster than the inner wheel. Friction in the differential will oppose motion, and that will work to ''slow'' the faster side and ''speed up'' the slower/inner side. This leads to asymmetric torque distributions in drive wheels, matching the TBR. Cornering in this manner will reduce the torque applied to the outer tire, leading to possibly greater cornering power, unless the inner wheel is overpowered (which is easier to do than with an open differential). When the inner tire (which has less traction due to weight transfer from lateral acceleration) is overpowered, it angularly accelerates up to the outer wheel speed (small percent wheel spin) and the differential locks, and if the traction difference does not exceed the TBR, the outer wheel will then have a higher torque applied to it. If the traction difference exceeds the TBR, the outer tire gets the tractive torque of the inner wheel multiplied by the TBR, and the remaining applied torque to the differential contributes to wheel spin up. When a Torsen differential is employed, the slower-moving wheel always receives more torque than the faster-moving wheel. The Torsen T-2R RaceMaster is the only Torsen to have a preload

clutch A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts ...

. So, even if a wheel is airborne, torque is applied to the other side. If one wheel were raised in the air, the regular Torsen units would act like an open differential, and no torque would be transferred to the other wheel. This is where the parking brake "trick" can help out. If the parking brake is applied, assuming that the parking brake applies even resistance to each side, then the drag to the airborne side is "multiplied" through the differential, and TBR times the drag torque is applied to the other side. So, the ground side would see (TBR X drag torque) minus drag torque, and that may restore motion either forward or in reverse. In Hummer/

HMMWV The High Mobility Multipurpose Wheeled Vehicle (HMMWV; colloquial: Humvee) is a family of light, four-wheel drive, military trucks and utility vehicles produced by AM General. It has largely supplanted the roles previously performed by the o ...

applications, there are both front and rear Torsen differentials, so the use of the main brakes will operate this "trick" on both axles simultaneously.

Torsen users

Torsen differentials are used in many of the various

quattro Quattro is Italian for the number four. Quattro may also refer to: People * "Quattro", a nickname of A. J. Foyt IV Fictional characters * Quattro Vageena or Quattro Bageena, an alias of Char Aznable in the ''Mobile Suit Gundam'' anime series ...

models, excluding the A3 and S3 and TT, which have transverse-mounted engines and use Haldex Traction 4WD systems. It is also used in the third- and fourth-generation

Toyota Supra is a sports car and grand tourer manufactured by the Toyota Motor Corporation beginning in 1978. The name " supra" is derived from the Latin prefix, meaning "above", "to surpass" or "go beyond". The initial four generations of the Supra were p ...

(Optional) and third-generation Toyota Soarer, the B5 platform revision of the

Volkswagen Passat The Volkswagen Passat is a series of large family cars manufactured and marketed by the German automobile manufacturer Volkswagen since 1973, and now in its eighth generation. It has been marketed variously as the Dasher, Santana, Quantum, Mago ...

4motion (based upon the

Audi A4 The Audi A4 is a line of compact executive cars produced since 1994 by the German car manufacturer Audi, a subsidiary of the Volkswagen Group. The A4 has been built in five generations and is based on the Volkswagen Group B platform. The fir ...

), Mazda MX-5/Miata 1994 to 1995 have a Torsen Type I and late 1995 to 2002 models have a Torsen Type II, the 2002-2003 model year of the

Nissan Maxima The Nissan Maxima is a full-size car manufactured and marketed by Nissan and offered as Nissan's flagship sedan primarily in North America, the Middle East, and China — and currently in its eighth generation. Having debuted for model year ...

SE 6 speed manual, the

Honda S2000 The Honda S2000 is an open top sports car that was manufactured by Japanese automobile manufacturer Honda, from 1999 until 2009. First shown as a concept car called the SSM at the Tokyo Motor Show in 1995, the production version was launched on ...

, and 1999-2002 S15 Nissan Silvia Spec R. The Lancia Delta Integrale, the

Peugeot 405 The Peugeot 405 is a large family car released by the French automaker Peugeot in July 1987, and which continues to be manufactured under licence outside France, having been discontinued in Europe in 1997. It was voted European Car of the Year for ...

T16, as well as the 1999-2002 model

Pontiac Firebird The Pontiac Firebird is an American automobile that was built and produced by Pontiac from the 1967 to 2002 model years. Designed as a pony car to compete with the Ford Mustang, it was introduced on February 23, 1967, five months after GM's ...

and

Chevrolet Camaro The Chevrolet Camaro is a mid-size American automobile manufactured by Chevrolet, classified as a pony car. It first went on sale on September 29, 1966, for the 1967 model year and was designed to compete with the Ford Mustang. The Camaro sh ...

, had a Torsen differential. Rover group fitted Torsen type 1, and later type 2, units to their range of high performance front wheel drive turbo models (220, 420, 620ti, and 800 Vitesse). The use of the Torsen differential was preferred by Rover group; it is much better at controlling wheel spin on front wheel drive vehicles than electronic systems which reduce engine power and therefore performance. The

Humvee The High Mobility Multipurpose Wheeled Vehicle (HMMWV; colloquial: Humvee) is a family of light, four-wheel drive, military trucks and utility vehicles produced by AM General. It has largely supplanted the roles previously performed by the ...

uses two Torsens, front and rear, with a normal manually lockable center differential (NVG242HD AMG transfer case) in the center. Other users of the Torsen limited-slip differential include the Toyota GT86 and the Subaru BRZ, both released in 2012. The first Ford company vehicle to use a Torsen differential was the 2002 Ford Ranger FX4, renamed in 2003+ years to FX4 Level II, all of which used T-2R in the rear differential only. Starting in 2012, the Ford F-150 SVT Raptor uses a front Torsen differential and the Ford Mustang Boss 302 uses a rear Torsen differential. AMG offered Torsen differentials as an option as early as 1988 for new as well as for retrofitting for 107, 116, 123, 126 series Mercedes Benz cars. Toyota Altezza (sold in Europe, the U.S. and Canada as Lexus IS200 and IS300) came with a Torsen differential. For Lexus models it was included with all IS300 models with manual transmission and with the IS200 Sport, and was optionally factory equipped with automatic transmission. The Toyota Altezza was standard on all manual transmission SXE10 models (with the 5th-generation Beams 3S-GE engine and J160 6-speed manual transmission).

Torsen applications

Center

Q4 versions: 156 Crosswagon & Sportwagon,

, Brera & Spider Q4 *

versions of

: **

Audi Quattro The Audi Quattro is a road and rally car, produced by the German automobile manufacturer Audi, part of the Volkswagen Group. It was first shown at the 1980 Geneva Motor Show on 3 March. Production continued through 1991. Background The wor ...

(1987-current) ** Audi 80 & 90, Audi S2, Audi RS2 Avant ** Audi 100 / Audi 200 / Audi 5000 ** Audi Coupé quattro **

, Audi S4,

Audi RS4 The Audi RS 4 is the high-performance variant of the Audi A4 range produced by Audi Sport GmbH for AUDI AG, a division of the Volkswagen Group. It sits above the Audi S4 as the fastest, most sports-focused car based on the A4's "B" automobile pl ...

Audi A5 The Audi A5 is a series of compact executive coupe cars produced by the German automobile manufacturer Audi since June 2007. The A5 range additionally comprises the coupe, cabriolet, and "Sportback" (a five-door liftback with a fastback roofline ...

, Audi S5, Audi RS5 **

, Audi S6, Audi RS6 ** Audi A7, Audi S7, Audi RS7 **

Audi A8 The Audi A8 is a full-size luxury sedan manufactured and marketed by the German automaker Audi since 1994. Succeeding the Audi V8, and now in its fourth generation, the A8 has been offered with both front- or permanent all-wheel drive—and i ...

, Audi S8 ** Audi allroad quattro ** Audi Q5, Audi SQ5 ** Audi Q7, Audi SQ7 ** Audi Q8, Audi SQ8, Audi RSQ8 ** Audi V8 (manual transmission) * Chevrolet TrailBlazer SS *

Land Rover Land Rover is a British brand of predominantly four-wheel drive, off-road capable vehicles, owned by multinational car manufacturer Jaguar Land Rover (JLR), since 2008 a subsidiary of India's Tata Motors. JLR currently builds Land Rove ...

Land Rover Discovery Land, also known as dry land, ground, or earth, is the solid terrestrial surface of the planet Earth that is not submerged by the ocean or other bodies of water. It makes up 29% of Earth's surface and includes the continents and various islan ...

(L319) (L462),

Land Rover Defender The Land Rover Defender (initially introduced as the Land Rover 110 / One Ten, and in 1984 joined by the Land Rover 90 / Ninety, plus the new, extra-length Land Rover 127 in 1985) is a series of British off-road cars and pickup trucks. They ...

(L663),

Range Rover Range may refer to: Geography * Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra) ** Mountain range, a group of mountains bordered by lowlands * Range, a term used to ...

(L322),(L405),(L460), Range Rover Sport (L320),(L494),(L461) * Lexus GX, LS 600h / LS 600h L, LX * Mitsubishi Triton 5th Generation * Saab 9-7X Aero *

: 4Runner (All 4WD 4Runner from 2003-2009) and 4Runner Limited (2010 to present), FJ Cruiser 6-speed manual, Toyota Landcruiser 200, Toyota Landcruiser 120/150, Toyota Fortuner, Toyota Land Cruiser Prado, Toyota Sequoia, Toyota Celica GT-Four/All-trac ST165, ST185, ST205, Toyota Caldina GTT and GT-Four *

Volkswagen Volkswagen (),English: , . abbreviated as VW (), is a German motor vehicle manufacturer headquartered in Wolfsburg, Lower Saxony, Germany. Founded in 1937 by the German Labour Front under the Nazi Party and revived into a global brand post ...

: Passat (badged as 4motion) (B5 platform),

Amarok Amarok may refer to: Music * Amarok (band), a Spanish progressive rock band * ''Amarok'' (Mike Oldfield album), 1990 * ''Amarok'' (Nargaroth album), 2000 * ''Amarok'', 2010 album by Francisco López (musician) Other uses * Amarok (wolf), in In ...

(permanent 4motion version only), Touareg (2011 to present, without offroad package)

Center and rear

* Audi V8 with manual transmission

Front and rear axles

* Mitsubishi Pajero Evolution * Toyota GR Yaris

Front axle only

* Honda/Acura Integra

Type R Honda Type R models are special performance editions of their respective model families. The design of Type R models was originally focused on race conditions, with an emphasis on minimizing weight, and maximizing performance potential (e.g. eng ...

: GT, 147 Q2 * Honda Civic Si (2006-current) *

Honda Civic The is a series of automobiles manufactured by Honda since 1972. Since 2000, the Civic has been categorized as a compact car, while previously it occupied the subcompact class. , the Civic is positioned between the Honda Fit/City and Hond ...

1.8 VTi Europe & UK (5-door & Aerodeck Wagon, 1996–2000) * Ford Focus RS *

Mitsubishi Pajero The Further information on the Mitsubishi P ...

SE 6 Speed manual *

Nissan Sentra The Nissan Sentra is a series of automobiles manufactured by the Japanese automaker Nissan since 1982. Since 1999, the Sentra has been categorized as a compact car, while previously it occupied the subcompact class. Until 2006, Sentra was a re ...

SE-R Spec-V * Oldsmobile Calais W41 (7 cars equipped from the factory, C41 option code) * Oldsmobile Achieva W41 (7-10 cars equipped from the factory, C41 option code) *

Rover 200 Coupe Rover may refer to: People * Constance Rover (1910–2005), English historian * Jolanda de Rover (born 1963), Dutch swimmer * Rover Thomas (c. 1920–1998), Indigenous Australian artist Places * Rover, Arkansas, US * Rover, Missouri, US * ...

Turbo, 200 BRM/LE, 220 Turbo, 420 Turbo, 620 Ti, 820 Vitesse (200PS version only) *

Honda Accord The , also known as the in Japan and China for certain generations, is a series of cars manufactured by Honda since 1976, best known for its four-door sedan variant, which has been one of the best-selling cars in the United States since 1989. ...

* Subaru Impreza STI (2005-current) *

Ford F-150 SVT Raptor The Ford F-Series is a series of light-duty trucks marketed and manufactured by Ford since the 1948 model year. Slotted above the Ford Ranger in the Ford truck model range, the F-Series is marketed as a range of full-sized pickup trucks. ...

(2012-current) * Renault Megane RS * Peugeot RCZ R * Peugeot 208 GTI by Peugeot Sport * Peugeot 308 GTI by Peugeot Sport

Rear axle only

* AMG retro-fitted and optional for: 107, 116, 123, 126 Mercedes cars * Audi V8 with automatic transmission *

Audi R8 The Audi R8 is a mid-engine, 2-seater sports car, which uses Audi's trademark quattro permanent all-wheel drive system. It was introduced by the German car manufacturer Audi AG in 2006. The car is exclusively designed, developed, and manufactu ...

: 155 Q4, 164 Q4 * BMW Z3 * Citroën BX 4x4 with ABS (same as Peugeot 405 4x4) * Dodge/Ram Heavy Duty Equipped with 11.5 AAM Rear Axle (2003-current) * Ford Ranger FX4 2002 only, Ranger FX4 Level II (2003-2009) *

* Hyundai Genesis Coupe * Lancia Delta Integrale *

Lexus IS The is a compact executive car sold by Lexus, a luxury division of Toyota since 1999. The IS was originally sold under the nameplate in Japan from 1998 (the word wiktionary:altezza, ''Altezza'' is Italian for 'height' or 'highness'). The IS was ...

Lexus IS F The Lexus IS (XE20) is the second generation of the Lexus IS line of compact executive cars. Sold by Lexus since 2005, the line includes multiple V6 gasoline-powered models, in four-door sedan and two-door coupé convertible body styles. Add ...

, Lexus LC,

Lexus LFA The is a two-seat sports car manufactured by Lexus, the luxury car division of Toyota. It is the second model in the F marque line of performance vehicles from Lexus, following the IS F, and also the first standalone Lexus F model. Three conc ...

, Lexus RC F, Lexus GS F * Maserati Biturbo *

Mazda , commonly referred to as simply Mazda, is a Japanese Multinational corporation, multinational Automotive industry, automotive manufacturer headquartered in Fuchū, Hiroshima (town), Fuchū, Hiroshima Prefecture, Hiroshima, Japan. In 2015, M ...

: Miata/MX-5 (option on 1994-2005 manual transmission models), RX-7,

RX-8 The Mazda RX-8 is a sports car manufactured by Japanese automobile manufacturer Mazda between 2002 and 2012. It was first shown in 2001 at the North American International Auto Show. It is the successor to the RX-7 and, like its predecessors in ...

* Nissan Silvia S15 SpecR * Nissan Skyline R34 GTT, 25GT-X, 25GT-V Manual *

4x4 with ABS (same as Citroën BX 4x4) * Peugeot 505 turbo sedan (1989 only) * Subaru Impreza WRX STI (2007–current) * Toyota Caldina ST215-W only * Toyota Celica GT-Four,

, Toyota Soarer, Toyota Aristo, Toyota Mark II,

Toyota Chaser The Toyota Chaser is a mid-size car produced by Toyota in Japan. Most Chasers are four-door sedans and hardtop sedans; a two-door hardtop coupé was available on the first generation only. It was introduced on the 1976 Toyota Corona Mark II pla ...

, Toyota Cresta, Toyota Verossa, Toyota Altezza,

Toyota RAV4 The is a compact crossover SUV produced by the Japanese automobile manufacturer Toyota. Considered the first ever compact crossover SUV, it made its debut in Japan and Europe in 1994, and in North America in 1995, being launched in January 19 ...

, Toyota MR2 Spyder, Limited, Toyota GR Yaris *

4th Generation (1999-2002) *

4th Generation (1999-2002) *Chevrolet Camaro SS, Pontiac Firehawk & Comp T/A 4th Generation (optional in 1996-1997) *Subaru Legacy Spec. B (2007-2009 in US market) * 2012 and 2013 Ford Mustang Boss 302, option. Standard on Laguna Seca Edition. * 2014 Ford Mustang Shelby GT500, option. * 2014 Ford Mustang GT, included in GT Track Package. * 2015-2017 Ford Mustang GT, included in Performance Package. * Toyota GT86 (also sold as the Subaru BRZ and Scion FR-S in various markets) *Ford F-450/500 Super Duty (1999-current)

References

{{reflist

External links

3D Animation of a Torsen DifferentialTorsen Traction official site

Torsen traction control article
(PDF)
Popular Science articleArticle from 1915 about the Muehl differential, a similar device
Automotive transmission technologies Automotive technology tradenames Audi