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GM 6L transmission

Motor vehicle automatic transmission models From Wikipedia, the free encyclopedia

GM 6L transmission
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The 6LXX family is a series of 6-speed longitudinally-mounted automatic transmissions produced by General Motors. The 6L80 and 6L90 were assembled at GM Powertrain plants in Ypsilanti, MI (Willow Run Transmission), Toledo, Ohio (Toledo Transmission) and Silao, Guanajuato, Mexico, while the smaller 6L45 and 6L50 were produced at those same Toledo and Silao plants, as well as at a GM Powertrain plant in Strasbourg, France. All four models feature clutch to clutch shifting, eliminating the one-way clutches used on older transmission designs.

Quick Facts 6L45 - 6L50 - 6L80 - 6L90, Overview ...

The series was first launched with the 6L80 in the 2006 Cadillac STS-V, with the remaining three versions all first appearing in 2007 model year vehicles. The 6L90 was a strengthened and uprated version of the 6L80, used primarily in heavy-duty truck/van applications. The 6L50 was used on V8-powered versions of the Cadillac STS sedan and Cadillac SRX crossover, and replaced the 5L40-E and 5L50 in GM's lineup. The 6L45 was a smaller version of the 6L50, used in certain BMW vehicles and the Cadillac ATS, as part of either rear-wheel drive and all-wheel drive powertrains.

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Specifications

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Technical Data

More information 6L45 6L50, 6L80 6L90 ...

Progress Gearset Concept

Main Objectives

The main objective in replacing the predecessor model was to improve vehicle fuel economy with extra speeds and a wider gear span to allow the engine speed level to be lowered (downspeeding). The layout brings the ability to shift in a non-sequential manner – going from gear 6 to gear 2 in extreme situations simply by changing one shift element (actuating clutch E and releasing brake A).

Extent

In order to increase the number of ratios, ZF has abandoned the conventional design method of limiting themselves to pure in-line epicyclic gearing and extended it to a combination with parallel epicyclic gearing. This was only possible thanks to computer-aided design and has resulted in a globally patent for this gearset concept. The 6L is based on the 6HP from ZF, which was the first transmission designed according to this new paradigm. After gaining additional gear ratios only with additional components, this time the number of components has to decrease while the number of ratios still increase. The progress is reflected in a much better ratio of the number of gears to the number of components used compared to existing layouts.

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Quality Gearset Concept

The ratios of the 6 gears are nicely evenly distributed in all versions. Exceptions are the large step from 1st to 2nd gear and the almost geometric steps from 3rd to 4th to 5th gear. They cannot be eliminated without affecting all other gears. As the large step is shifted due to the large span to a lower speed range than with conventional gearboxes, it is less significant. As the gear steps are smaller overall due to the additional gear(s), the geometric gear steps are still smaller than the corresponding gear steps of conventional gearboxes. Overall, therefore, the weaknesses are not overly significant. As the selected gearset concept saves up to 2 components compared to 5-speed transmissions, the advantages clearly outweigh the disadvantages.

It has a torque converter lock-up for all 6 forward gears, which can be fully disengage when stationary, largely closing the fuel efficiency gap between vehicles with automatic and manual transmissions.

In a Lepelletier gearset,[1] a conventional planetary gearset and a composite Ravigneaux gearset are combined to reduce both the size and weight as well as the manufacturing costs. Like all transmissions realized with Lepelletier transmissions, the 6L also dispenses with the use of the direct gear ratio and is thus one of the very few automatic transmission concepts without such a ratio.

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Applications

6L45

6L50

6L80

6L90

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See also

  • List of GM transmissions
  • "GM Launches More Fuel-Saving Six-Speed Automatic Transmissions". GM Media Online. Retrieved June 18, 2006. [dead link]
  • Cadillac PDF info on 6L80-E Transmission: http://www.cadillacfaq.com/stsfaq/tsb/data/tsb/05-07-30-023.pdf
  • "GM Ypsilanti Begins 6-Speed Production". Automotive Design and Production. Archived from the original on March 3, 2006. Retrieved January 3, 2006.

References

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