GM 6L transmission

The 6L family is a series of 6-speed automatic transmissions produced by General Motors for longitudinal engines. It uses a Lepelletier planetary gearset, an epicyclic gearset, which can provide more gear ratios with significantly fewer components than prior models could.

It was first realized in 2000 with the 6HP from ZF Friedrichshafen. The Ford 6R, AWTF-80 SC, and ZF 6HP transmissions are based on the same globally patented gearset concept. The AWTF-80 SC is the only one for transverse engine installation.

Key data

+ Gear ratios Model FirstDeliv-ery Gear Total Span Avg.Step Components Nomenclature R 1 2 3 4 5 6 Nomi-nal Effec-tive Cen-ter Total perGear GearsCount Cou-pling Gear-sets Maximum Input Torque 6L 45 · 6L 50 2005 3Gearsets2 Brakes3 Clutches 6 L 6L 80 · 6L 90 2005 · ZF 6HP 2000 H P –

History

The series was first launched with the 6L 80 in the 2006 Cadillac STS-V, with the remaining three versions all first appearing in 2007 model year vehicles. The 6L 90 was a strengthened and uprated version of the 6L 80, used primarily in heavy-duty truck/van applications. The 6L 50 was used on V8-powered versions of the Cadillac STS sedan and Cadillac SRX crossover, and replaced the 5L 40-E and 5L 50 in GM's lineup. The 6L 45 was a smaller version of the 6L 50, used in certain BMW vehicles and the Cadillac ATS, as part of either rear-wheel drive and all-wheel drive powertrains.

Production

The 6L 80 and 6L 90 were assembled at GM Powertrain plants in Ypsilanti, MI (Willow Run Transmission), Toledo, Ohio (Toledo Transmission) and Silao, Guanajuato, Mexico, while the smaller 6L 45 and 6L 50 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.

Planetary gearset concept

Improved fuel economy

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), which is a decisive factor in improving energy efficiency and thus reducing fuel consumption. In addition, the lower engine speed level improves the noise-vibration-harshness comfort and the exterior noise is reduced. 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.

Reduced manufacturing complexity

In order to avoid a further increase in manufacturing complexity while expanding the number of gear ratios, ZF switched from the conventional design method—in which the planetary gearset concept was limited to a purely serial or in-line power flow—to a more modern design method that utilizes a planetary gearset concept with combined parallel and serial power flow. This was only possible thanks to computer-aided design and has resulted in a globally patented 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 resulting progress is reflected in a much better ratio of the number of gears to the number of components used compared to existing layouts.

Quality

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.

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).

In a Lepelletier planetary gearset, 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.

Applications

+ Variants and applications Model Car Model 6L 45 2007–2010: BMW X3 - 3.0si / 2.5si / 3.0i 2007–2013: BMW 3 series - 330(x)i / 328(x)i / 325(x)i / 323i / 320i / 318i / 316i 2007–2019: BMW 1 series - 130i / 128i / 125i / 120i / 118i / 116i 2009–2015: BMW X1 (E84) - 2.8i xDrive / 2.5i xDrive / 1.8i sDrive 2013–2015: Cadillac ATS 2010–2013: Cadillac SLS 2012–2017: Chevrolet Caprice PPV V6 2011–2013: Holden VE Commodore, Calais, SV6 2013–2017: Holden VF Commodore, Calais, SV6 6L 50 2007–2011: Cadillac SLS 2007–2011: Cadillac STS 2007–2009: Cadillac SRX 2008–2015: Cadillac CTS 2010–2015: Camaro LS/LT (V6 Models) 2009–2011: Holden VE Commodore / Holden VE Berlina / Holden VE Calais / Chevrolet Lumina / Chevrolet Omega 2009–2011: Holden WM Statesman/Caprice / Daewoo Veritas 2015–2022: Chevrolet Colorado 2017–2020: Tata Hexa 2019–2023: UAZ Patriot 2022: Bremach 6L 80 2006–2009 Cadillac XLR-V 2006–2013 Chevrolet Corvette 2006 Holden VE Commodore/2008-2009 Pontiac G8 2006–2013 Holden/Chevrolet WM Statesman/Caprice 2014–2017 Holden/Chevrolet WN Statesman/Caprice 2007–2013 GMC Sierra Denali 2009–2013 Chevrolet Silverado 1500 5.3 (ext. & crew cab), 6.2 2009–2013 GMC Sierra 1500 5.3 (ext. & crew cab), 6.2 2010–2013 Chevrolet Silverado 1500 5.3 (reg. cab) 2010–2013 GMC Sierra 1500 5.3 (reg. cab) 2006–2009 Cadillac STS-V 2007–2015 Cadillac Escalade 2007–2015 Cadillac Escalade ESV 2007–2013 Cadillac Escalade EXT 2007–2015 GMC Yukon Denali 2009–2020 Chevrolet Tahoe 2009–2020 GMC Yukon 2009–2020 Chevrolet Suburban 1500 2009–2020 GMC Yukon XL 2008–2009 Hummer H2 2014–2019 (K2XX) Chevrolet Silverado/GMC Sierra 1500 2010–2015 Chevrolet Camaro 2011–2017 Chevrolet Caprice 2011–2013 Holden VE Commodore Series 2(MY 2012) 2014–2017 Holden VF Commodore / Chevrolet SS 2009–2013 Chevrolet Avalanche 2019–2021 (T1XX) Chevrolet Silverado/GMC Sierra 1500 6L 90 2007–2014 Chevrolet Silverado 2500HD/3500 HD 6.0 2007–2014 GMC Sierra 2500HD/3500HD 6.0 2010–2023 Chevrolet Express 2500–3500 2010–2023 GMC Savana 2500–3500 2008–2019 Chevrolet Suburban 2500 2009–2013 Cadillac CTS-V 2012–2015 Chevrolet Camaro ZL1 2015–2019 Chevrolet Silverado 2500HD/3500 HD 6.0 2015–2019 GMC Sierra 2500HD/3500HD 6.0 2020–2023 Chevrolet Silverado 2500HD/3500 HD 6.6 L8T 2020–2023 GMC Sierra 2500HD/3500HD 6.6 L8T

GM 6L transmission

Bron en licentie