The General Motors 6T40 6-speed automatic transmission has been assembled at the company’s plants since 2007 and is installed in front-wheel drive models designated MH8 and all-wheel drive models designated MHB. There is also a hybrid version, the MHH, and a Gen 3 modification designated MNH.
Specifications
| Type | automatic transmission |
| Number of gears | 6 |
| Type of drive | front / all wheel |
| Engine volume, l | up to 2.5 |
| Torque output, Nm | up to 240 |
| Recommended oil | DEXRON VI |
| Oil capacity, liter | 8.2 |
| Partial replacement, liter | 5.0 |
| Maintenance | every 60 000 km |
| Gearbox lifespan, km | ~250 000 km |
| Weight, kg | 82 |
In 2007, General Motors introduced a full line of automatic transmissions for front- and all-wheel-drive vehicles with transverse powertrains. The 6T40 transmission is considered the mid-range model and is compatible with engines up to 240 Nm of torque. A separate version of this automatic transmission, designated MHH, is available for the eAssist hybrid powertrain.
Gear ratios GM 6T40
Using the 2015 Chevrolet Orlando with a 1.8-liter engine as an example:
| Main | 4.28 |
| 1st | 4.584 |
| 2nd | 2.964 |
| 3rd | 1.912 |
| 4th | 1.446 |
| 5th | 1.000 |
| 6th | 0.746 |
| Reverse | 2.943 |
Using
The transmission was installed on:
- Buick LaCrosse 2 (GMX353) in 2012 – 2016; LaCrosse 3 (P2XX) in 2016 – 2019;
- Buick Encore 1 (GMT165) in 2012 – 2022;
- Buick Regal 5 (GMX350) in 2012 – 2017;
- Buick Verano 1 (D1SB) in 2010 – 2016;
- Chevrolet Captiva 1 (C140) in 2011 – 2018;
- Chevrolet Cruze 1 (J300) in 2008 – 2016;
- Chevrolet Epica 1 (V250) in 2008 – 2014;
- Chevrolet Equinox 3 (D2XX) in 2017 – …;
- Chevrolet Malibu 7 (GMX386) in 2007 – 2012; Malibu 8 (V300) in 2011 – 2016; Malibu 9 (V400) in 2015 – 2018;
- Chevrolet Impala 10 (GMX352) in 2013 – 2019;
- Chevrolet Orlando 1 (J309) in 2010 – 2018;
- Chevrolet Sonic 1 (T300) in 2011 – 2020;
- Chevrolet Trax 1 (U200) in 2013 – 2022; Trax 2 (9BQC) in 2023 – …;
- Daewoo Tosca 1 (V250) in 2008 – 2011;
- Opel Astra J (P10) in 2009 – 2018;
- Opel Antara A (L07) in 2010 – 2015;
- Opel Insignia B (Z18) in 2017 – 2020;
- Opel Mokka A (J13) in 2012 – 2019;
- Opel Zafira C (P12) in 2011 – 2019;
- Pontiac G6 1 (GMX381) in 2008 – 2010;
- Saturn Aura 1 (GMX354) in 2008 – 2009.
Disadvantages of the GM 6T40 gearbox
- The most common problem with this automatic transmission is the weak spring disc of the 3-5-R drum. It simply breaks, then breaks its locking mechanism, and debris scatters throughout the system. Despite numerous upgrades to the transmission design, such failures still occur.
- Also worth noting is the rather aggressive settings of the transmission control unit, which causes the torque converter lockup clutch to wear out very quickly. The solenoids in this transmission do not tolerate dirty lubricant and often fail before 80,000 km.
- Weaknesses of this automatic transmission also include the limited life of the sliding bushings, rapid contamination of the speed sensors, and an insufficient standard cooling system. The differential is not particularly reliable, and in the first transmissions, its bolts would even come loose.
