M90 is the model designation for an automotive

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 ...

gearbox Propulsion transmission is the mode of transmitting and controlling propulsion power of a machine. The term ''transmission'' properly refers to the whole drivetrain, including clutch, gearbox, prop shaft (for rear-wheel drive vehicles), differe ...

that was introduced in mid-1994 Volvo 940/960.The M90 RWD gearbox and the M56 FWD gearbox are considered to be brother and sister because they are built on the same gearbox platform and have many parts in common. All turbocars have the M90 gearbox as standard from 1995. The gearbox is made by

Getrag Getrag (), stylized as GETRAG, was a major supplier of transmission systems for passenger cars and commercial vehicles. The company was founded on 1 May 1935, in Ludwigsburg, Germany, by Hermann Hagenmeyer; as the ''Getriebe und Zahnradfabrik ...

in Germany and it is of a 3-axle design, deriving from the

Volvo The Volvo Group ( sv, Volvokoncernen; legally Aktiebolaget Volvo, shortened to AB Volvo, stylized as VOLVO) is a Swedish multinational manufacturing corporation headquartered in Gothenburg. While its core activity is the production, distributio ...

M56 gearbox of the front wheel driven 850 series. There are three variations of the gearbox. There is a version for the cast-iron 4-cylinder engines of the 940 ( redblock), the all aluminum 6-cylinder of the 960 ( whiteblock), and the version for the

Volkswagen Volkswagen (),English: , . abbreviated as VW (), is a German Automotive industry, 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 ...

6-cylinder diesel engine

D24TIC The Volkswagen D24TIC is a 2.4-litre inline-six-cylinder (R6/I6) single overhead camshaft (SOHC) diesel engine, formerly manufactured by Volkswagen Group from August 1986 to December 1998.ETKA Technical description and rated outputs The engine i ...

. The differences are the bell housing bolt pattern and the output shaft flange with a 3-bolt flange for the redblock/diesel engines and a 4 bolt flange for whiteblock engines. The variant for the 6-cylinder Volvo engine will fit on all 4/5/6 all-aluminum Volvo N/RN-series engines. The clutch is hydraulically operated by a master/slave cylinder setup with a normal

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). ...

fork and throw out bearing. The flywheels used with these gearboxes are dual mass versions (petrol engines) to eliminate the noise that 3-axle (3-shift) gearboxes can make in neutral, and a regular (single mass) flywheels for the diesel engine. All gears, including the reverse gear, are synchronized. The M90 gearbox is available with different gear ratios.http://i45.tinypic.com/2qamxhl.jpg This gearbox is the strongest manual transmission that Volvo fitted to their rear-wheel-drive cars. The H2 and L2 versions are stronger than the H and L versions. There is a common disbelief that H is stronger than L, but the only difference between H and L is the gear ratio. In 1997, M90 H2 and M90 L2 were introduced. This revised model of the M90, had an improved design of the 3rd gear synchronous ring; to prevent premature failure of the transmission. But they did not improve on the stopring flange for 3rd gear. It is possible to modify the stopring of the M90 H and M90 L gearboxes, to eliminate the problem. To do so, one must open up the transmission and weld the stopring in its place. There is a misconception that you can weld the synchronous ring, when its in fact the stopring that needs welding in order for the 3rd gear to not travel out of reach from the ingresses. It's an easy fix for both the old and revised transmissions.

References

{{DEFAULTSORT:Volvo M90 Transmission Volvo Cars