6l80E
01-26-2007, 05:04 PM
#11
TECH Veteran
Originally Posted by maddboost
Im not saying its a great transmission but to say a 4L60E cant be built to handle over 300 hp is incorrect. It does have it limitations but well over 300 hp if built correctly.
The fundamental design of the 700R4 was intended to link a 250HP powerplant to a drivetrain in a 3500 lb. vehicle (which is why some F-Body guys do okay with a built 4L60E). Improvements have come along, but not enough to overcome the limitations of the initial design. Hence the 'dick-in-the-dirt' TM programmed into any heavy truck with decent power.
01-28-2007, 05:52 AM
#12
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The V MAX have the same head and intake and cam(maybe) is this true. I mean if it is there is 400 hp with a tune waiting there to come alive when the 6l80 comes out. I was thinking I was just going to get a Dmax cause how the new V maX run . My wife SS ran 14.8 stock and I was like how am I going to buy an new slower truck. I was kinda down on the new trucks cause of the times I saw from the new vmax. I guess we will see. hope the 6l80e makes the new VMAX run mid 14s(I don't think it will but it should)
05-05-2007, 09:36 PM
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Originally Posted by TBSS
What I said was I have a 400HP engine in a 4800 lb. truck with a transmission that can't handle 400HP in a 4800 lb. truck. If it could handle it, it wouldn't have so much torque management programmed in. You can certainly take the TM out, but then you need to start counting in weeks or months (rather than years) how much life is left in the tranny.
The fundamental design of the 700R4 was intended to link a 250HP powerplant to a drivetrain in a 3500 lb. vehicle (which is why some F-Body guys do okay with a built 4L60E). Improvements have come along, but not enough to overcome the limitations of the initial design. Hence the 'dick-in-the-dirt' TM programmed into any heavy truck with decent power.
The fundamental design of the 700R4 was intended to link a 250HP powerplant to a drivetrain in a 3500 lb. vehicle (which is why some F-Body guys do okay with a built 4L60E). Improvements have come along, but not enough to overcome the limitations of the initial design. Hence the 'dick-in-the-dirt' TM programmed into any heavy truck with decent power.
06-13-2007, 11:43 PM
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Originally Posted by treyZ28
30k miles on my 65 with zero torque management w/ an LQ9 + catback + aggressive tuning. Looked like new when rebuilt.
It didn't look new when rebuilt....
06-15-2007, 03:40 PM
#16
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Originally Posted by Wide Open
Anyone tried to do this engine and transmission swap yet?
None that I've seen- but I understand that there is a seperate 'box' that is the brains controlling the transmission...........
06-15-2007, 11:15 PM
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Here is some interesting reading...
FOR RELEASE: 2006-06-05
GM Launches More Fuel-Saving Six-Speed Automatic Transmissions
BEDFORD , Ind. –GM’s plan to offer one million vehicles annually with six-speed automatics by 2008 accelerates in 2006 and 2007 with nearly 40 global vehicle applications of the fuel-saving transmissions. Models of the 2007 Cadillac STS and SRX, as well as the Saturn Aura, Outlook and Pontiac G6, highlight the vehicles offered with new six-speed automatics.
Other models already on sale include the GMC Yukon Denali family, the Cadillac XLR-V, STS-V and Escalade lineup, and the Chevrolet Corvette. GM’s full-size heavy duty pickups are also equipped with an Allison 1000 six-speed automatic when equipped with the Duramax 6.6L turbo-diesel engine.
New 2007 model year six-speed automatic transmission variants include the Hydra-Matic 6T70 and 6T75 for front and all-wheel drive vehicles, as well as the Hydra-Matic 6L50 for rear and all-wheel drive vehicles. The 6L50 benefits from the expertise developed with the larger 6L80 rear-wheel drive six-speed transmission (initially in the 2006 model year), and is the second variant in the Hydra-Matic rear-wheel drive six-speed transmission family.
Advantages of a six-speed automatic include improved fuel economy, performance and a shift feel that is seamless to the customer. The six-speed automatic enables a reduced engine rpm at highway cruising speeds. A lower engine speed reduces engine wear and noise, and improves fuel economy.
“It’s a best-of-both-worlds scenario with the six-speed automatic, delivering great performance and enabling improved fuel economy,” said Jim Lanzon, executive director of transmission engineering for GM Powertrain. “It is almost like having two transmissions in one – the high numeric al first gear provides tremendous off-the-line acceleration, but the transmission is able to use the six gears to evenly distribute the torque and settle at an overdrive gear that helps deliver great fuel economy.”
Vehicle performance is enhanced with a six-speed, because smaller “steps” are used between gears, compared to a conventional four-speed automatic. This allows the transmission to quickly find the best gear for the vehicle speed and road conditions – there’s less back-and-forth hunting on grades, for example. GM’s new Hydra-Matic six-speeds also use technically advanced clutch-to-clutch operation, which reduces mass, complexity and enables compact packaging. A wide, 6.04:1 overall ratio on most of GM’s six-speeds, compared to 4.0 of typical four-speed automatics, delivers both great performance and improved fuel economy.
“The mechanical simplicity of the clutch-to-clutch shift operation in our new six-speed automatic transmission families, along with a conscious effort to reduce part complexity, is providing us greater flexibility and the ability to launch with a broad application across the GM portfolio,” said Lanzon. “By 2010, GM will introduce 10 new variants of six-speed automatic transmissions, producing three million six-speeds annually.”
GM’s six-speed transmissions also provide tremendous flexibility to customize features for each vehicle brand, such as tapshift range selection, auto grade braking and a tow/haul mode.
New 6T70 and 6T75 FWD transmissions
The new Hydra-Matic 6T70 and 6T75 six-speed automatics are advanced transmissions with clutch-to-clutch shift operation for front- and all-wheel drive vehicles. The transmissions are based on a common design, with the 6T75 rated for higher torque capacity. The 6T70 debuts on the Saturn Aura and on a Pontiac G6 model; the 6T75 will be offered on the Saturn Outlook
The 6T70/75’s clutch-to-clutch operation and 6.04:1 overall ratio help the transmission deliver both performance and fuel economy, enabling up to 7 percent improved performance and up to 4 percent improved fuel economy when compared with current front-wheel drive four-speed automatics. Both transmissions use a very high numerical 4.48:1 first gear, which helps deliver exceptional launch feel, and a 0.74:1 overdrive sixth gear, which reduces engine rpms at high speeds, thereby reducing engine noise and vibrations. Fifth gear is 1:1 direct drive.
With its wide ratio and strong capacity, the 6T70/75 has the capability to transfer more torque to the drive wheels, particularly in all-wheel drive applications. It also helps vehicles, such as crossovers like the Outlook, to feel even livelier at lower speeds, particularly at launch or when pulling away from a stoplight.
The 6T70/75 offers the capability of driver shift control (DSC), which allows the driver to use tap-up/tap-down shifting to select the desired gear for specific road conditions, such as driving up a steep hill. A sophisticated transmission electro-hydraulic control module (TEHCM) is mounted inside the 6T70 and 6T75, reducing vehicle complexity. Similar to the control system used in the six-speed Hydra-Matic rear-wheel drive transmissions, the TEHCM offers improved quality through its hard-wired connections. The unit is located entirely within the transmission and operates while bathed in transmission fluid. Locating the controller internally facilitates the modular design and assembly strategy while also shielding the unit from the outside environment.
The 6T70/75 was co-developed with Ford Motor Co. Co-development of the transmission allowed it to reach production in less time and enabled each company to reduce development costs by as much as 50 percent. A common on-axis design and many common components are shared between GM and Ford Motor Co. The controls, calibrations and operation of the transmissions are unique to each company.
New 6L50 RWD and AWD six-speed
A new Hydra-Matic 6L50 six-speed transmission debuts in certain 2007 Cadillac STS rear- and all-wheel drive performance sedans and the V-8-powered SRX crossover SUV. The 6L50 is the second model of four new variants in the RWD six-speed transmission family. The 6L50 is designed with the same modular flexibility as the larger 6L80 and is fully compatible by using the same advanced electronic controls. As with the 6L80, the 6L50’s gearset configuration enables the same 6.04 wide overall ratio.
As with other GM six-speeds, the 6L50 delivers smaller steps between gears, enabling the vehicle to quickly find the best gear. A higher numerical first gear delivers strong acceleration from a standstill and two overdrive gears enable improved fuel economy through lower engine rpms at cruising speed. Also, the lower rpm achieved with the sixth gear reduces engine noise and vibration on the highway.
The 6L50 also uses the Driver Shift Control feature, which allows the driver to shift the transmission like a clutchless manual gearbox. Also, the transmission is calibrated to override the automatic gear selection during closed-throttle, high-lateral acceleration maneuvers, rapidly downshifting with nearly synchronous engine speed matching for quick power-up when the throttle is reopened. This gives the feel of a manual transmission during deceleration. Electronic safeguards prevent over-revving.
6L80 RWD six-speed
The Hydra-Matic 6L80 six-speed automatic transmission was the first of four variants in the rear-wheel drive transmission family designed with modular flexibility and compatibility with advanced electronic controls. It also features clutch-to-clutch operation, manual range selection and an integrated 32-bit electro-hydraulic controller. It debuted in 2006 on the Cadillac XLR-V, STS-V and Chevrolet Corvette, where it is offered with paddle-shift control.
The 6L80 also is tailored for the heavy-duty requirements of SUVs and trucks, and is offered on GM’s 2007 full-size SUVs equipped with the Vortec 6.2L V-8, such as the GMC Yukon Denali and Cadillac Escalade. In all applications, the 6L80 has a wide, 6.04:1 overall ratio – including two overdrive gears – that helps deliver up to 7 percent improved 0 – 60 mph performance and up to 4 percent improved fuel economy.
The 6L80’s six forward gears have smaller “steps” between them, which bolsters both performance and the feeling of smoothness. The smaller steps also enable a steep, 4.02:1 first gear, which provides an improved-performance launch feel. And with two overdrive gears, engine rpm is reduced by approximately 9 percent at 60 mph – a reduction of about 1,350 rpm.
A 32-bit electro-hydraulic control module optimizes transmission performance according to a variety of vehicle inputs, while also enabling features including tow/haul mode, auto grade braking and manual range selection. The controller is integrated within the transmission.
Tow/haul mode is a driver-selectable feature of the 6L80 that reduces shift busyness when towing or hauling a heavy load. The feature is complemented by manual range selection, which allows the driver to block out upper gears and select desired gears for unique driving conditions, such as towing on a steep grade. The manual range selection feature increases the feeling of control by holding the gear pre-selected by the driver. Electronic safeguards prevent the transmission from being shifted in a manner that could cause engine damage or loss of vehicle control. Auto grade braking is available when the tow/haul mode is selected and the transmission is not in the range selection mode.
I have attached the actual specifications if anyone was interested.....
GM Launches More Fuel-Saving Six-Speed Automatic Transmissions
BEDFORD , Ind. –GM’s plan to offer one million vehicles annually with six-speed automatics by 2008 accelerates in 2006 and 2007 with nearly 40 global vehicle applications of the fuel-saving transmissions. Models of the 2007 Cadillac STS and SRX, as well as the Saturn Aura, Outlook and Pontiac G6, highlight the vehicles offered with new six-speed automatics.
Other models already on sale include the GMC Yukon Denali family, the Cadillac XLR-V, STS-V and Escalade lineup, and the Chevrolet Corvette. GM’s full-size heavy duty pickups are also equipped with an Allison 1000 six-speed automatic when equipped with the Duramax 6.6L turbo-diesel engine.
New 2007 model year six-speed automatic transmission variants include the Hydra-Matic 6T70 and 6T75 for front and all-wheel drive vehicles, as well as the Hydra-Matic 6L50 for rear and all-wheel drive vehicles. The 6L50 benefits from the expertise developed with the larger 6L80 rear-wheel drive six-speed transmission (initially in the 2006 model year), and is the second variant in the Hydra-Matic rear-wheel drive six-speed transmission family.
Advantages of a six-speed automatic include improved fuel economy, performance and a shift feel that is seamless to the customer. The six-speed automatic enables a reduced engine rpm at highway cruising speeds. A lower engine speed reduces engine wear and noise, and improves fuel economy.
“It’s a best-of-both-worlds scenario with the six-speed automatic, delivering great performance and enabling improved fuel economy,” said Jim Lanzon, executive director of transmission engineering for GM Powertrain. “It is almost like having two transmissions in one – the high numeric al first gear provides tremendous off-the-line acceleration, but the transmission is able to use the six gears to evenly distribute the torque and settle at an overdrive gear that helps deliver great fuel economy.”
Vehicle performance is enhanced with a six-speed, because smaller “steps” are used between gears, compared to a conventional four-speed automatic. This allows the transmission to quickly find the best gear for the vehicle speed and road conditions – there’s less back-and-forth hunting on grades, for example. GM’s new Hydra-Matic six-speeds also use technically advanced clutch-to-clutch operation, which reduces mass, complexity and enables compact packaging. A wide, 6.04:1 overall ratio on most of GM’s six-speeds, compared to 4.0 of typical four-speed automatics, delivers both great performance and improved fuel economy.
“The mechanical simplicity of the clutch-to-clutch shift operation in our new six-speed automatic transmission families, along with a conscious effort to reduce part complexity, is providing us greater flexibility and the ability to launch with a broad application across the GM portfolio,” said Lanzon. “By 2010, GM will introduce 10 new variants of six-speed automatic transmissions, producing three million six-speeds annually.”
GM’s six-speed transmissions also provide tremendous flexibility to customize features for each vehicle brand, such as tapshift range selection, auto grade braking and a tow/haul mode.
New 6T70 and 6T75 FWD transmissions
The new Hydra-Matic 6T70 and 6T75 six-speed automatics are advanced transmissions with clutch-to-clutch shift operation for front- and all-wheel drive vehicles. The transmissions are based on a common design, with the 6T75 rated for higher torque capacity. The 6T70 debuts on the Saturn Aura and on a Pontiac G6 model; the 6T75 will be offered on the Saturn Outlook
The 6T70/75’s clutch-to-clutch operation and 6.04:1 overall ratio help the transmission deliver both performance and fuel economy, enabling up to 7 percent improved performance and up to 4 percent improved fuel economy when compared with current front-wheel drive four-speed automatics. Both transmissions use a very high numerical 4.48:1 first gear, which helps deliver exceptional launch feel, and a 0.74:1 overdrive sixth gear, which reduces engine rpms at high speeds, thereby reducing engine noise and vibrations. Fifth gear is 1:1 direct drive.
With its wide ratio and strong capacity, the 6T70/75 has the capability to transfer more torque to the drive wheels, particularly in all-wheel drive applications. It also helps vehicles, such as crossovers like the Outlook, to feel even livelier at lower speeds, particularly at launch or when pulling away from a stoplight.
The 6T70/75 offers the capability of driver shift control (DSC), which allows the driver to use tap-up/tap-down shifting to select the desired gear for specific road conditions, such as driving up a steep hill. A sophisticated transmission electro-hydraulic control module (TEHCM) is mounted inside the 6T70 and 6T75, reducing vehicle complexity. Similar to the control system used in the six-speed Hydra-Matic rear-wheel drive transmissions, the TEHCM offers improved quality through its hard-wired connections. The unit is located entirely within the transmission and operates while bathed in transmission fluid. Locating the controller internally facilitates the modular design and assembly strategy while also shielding the unit from the outside environment.
The 6T70/75 was co-developed with Ford Motor Co. Co-development of the transmission allowed it to reach production in less time and enabled each company to reduce development costs by as much as 50 percent. A common on-axis design and many common components are shared between GM and Ford Motor Co. The controls, calibrations and operation of the transmissions are unique to each company.
New 6L50 RWD and AWD six-speed
A new Hydra-Matic 6L50 six-speed transmission debuts in certain 2007 Cadillac STS rear- and all-wheel drive performance sedans and the V-8-powered SRX crossover SUV. The 6L50 is the second model of four new variants in the RWD six-speed transmission family. The 6L50 is designed with the same modular flexibility as the larger 6L80 and is fully compatible by using the same advanced electronic controls. As with the 6L80, the 6L50’s gearset configuration enables the same 6.04 wide overall ratio.
As with other GM six-speeds, the 6L50 delivers smaller steps between gears, enabling the vehicle to quickly find the best gear. A higher numerical first gear delivers strong acceleration from a standstill and two overdrive gears enable improved fuel economy through lower engine rpms at cruising speed. Also, the lower rpm achieved with the sixth gear reduces engine noise and vibration on the highway.
The 6L50 also uses the Driver Shift Control feature, which allows the driver to shift the transmission like a clutchless manual gearbox. Also, the transmission is calibrated to override the automatic gear selection during closed-throttle, high-lateral acceleration maneuvers, rapidly downshifting with nearly synchronous engine speed matching for quick power-up when the throttle is reopened. This gives the feel of a manual transmission during deceleration. Electronic safeguards prevent over-revving.
6L80 RWD six-speed
The Hydra-Matic 6L80 six-speed automatic transmission was the first of four variants in the rear-wheel drive transmission family designed with modular flexibility and compatibility with advanced electronic controls. It also features clutch-to-clutch operation, manual range selection and an integrated 32-bit electro-hydraulic controller. It debuted in 2006 on the Cadillac XLR-V, STS-V and Chevrolet Corvette, where it is offered with paddle-shift control.
The 6L80 also is tailored for the heavy-duty requirements of SUVs and trucks, and is offered on GM’s 2007 full-size SUVs equipped with the Vortec 6.2L V-8, such as the GMC Yukon Denali and Cadillac Escalade. In all applications, the 6L80 has a wide, 6.04:1 overall ratio – including two overdrive gears – that helps deliver up to 7 percent improved 0 – 60 mph performance and up to 4 percent improved fuel economy.
The 6L80’s six forward gears have smaller “steps” between them, which bolsters both performance and the feeling of smoothness. The smaller steps also enable a steep, 4.02:1 first gear, which provides an improved-performance launch feel. And with two overdrive gears, engine rpm is reduced by approximately 9 percent at 60 mph – a reduction of about 1,350 rpm.
A 32-bit electro-hydraulic control module optimizes transmission performance according to a variety of vehicle inputs, while also enabling features including tow/haul mode, auto grade braking and manual range selection. The controller is integrated within the transmission.
Tow/haul mode is a driver-selectable feature of the 6L80 that reduces shift busyness when towing or hauling a heavy load. The feature is complemented by manual range selection, which allows the driver to block out upper gears and select desired gears for unique driving conditions, such as towing on a steep grade. The manual range selection feature increases the feeling of control by holding the gear pre-selected by the driver. Electronic safeguards prevent the transmission from being shifted in a manner that could cause engine damage or loss of vehicle control. Auto grade braking is available when the tow/haul mode is selected and the transmission is not in the range selection mode.
I have attached the actual specifications if anyone was interested.....
Last edited by Ws6Extreme; 06-15-2007 at 11:23 PM.
06-15-2007, 11:24 PM
#18
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FOR RELEASE: 2006-02-27
GM's Hydra-Matic 6L80 Six Speed Automatic Delivers Balanced Performance, Economy For Full-Size SUV's
* Manufactured at GM's Toledo, Ohio and Ypsilanti, Mich. manufacturing plants
* One of the most sophisticated transmissions in the industry with clutch-to-clutch operation
* Wide 6.04:1 ratio spread delivers excellent balance of performance and fuel economy
* Approximately 9-percent reduction in engine rpm at 60 mph (compared to the 4L60 four-speed transmission) for enhanced fuel economy and NVH characteristics
* Tow/haul mode and auto grade braking for optimal towing performance
* Manual range selection for driver-selectable performance
TOLEDO, Ohio - A new GM Hydra-Matic 6L80 rear-wheel drive six-speed electronically controlled automatic transmission designed for the performance requirements of trucks debuts in GM's 2007 full-size SUVs. It is one of the most technologically advanced transmissions in the industry, featuring clutch-to-clutch operation, manual range selection and an integrated 32-bit electro-hydraulic controller.
The 6L80 is available on vehicles equipped with the Vortec 6.2L V-8 engine. A wide, 6.04:1 overall ratio - including two overdrive gears - helps deliver an excellent balance of performance and fuel economy. It is similar to the six-speed "paddle shift" automatic transmission introduced on the 2006 Corvette, but has been tailored for the heavy-duty requirements of SUVs and trucks.
"There are no compromises with the Hydra-Matic 6L80 transmission - it delivers great performance and enables improved fuel economy on the highway, all with smooth, almost imperceptible operation," said Jeff Baran, chief engineer for six-speed rear-wheel drive transmissions. "Complementing its sophisticated performance characteristics is the tough capability necessary for the demanding duty cycle of trucks and the tasks their drivers ask of them."
The Hydra-Matic 6L80's six forward gears have smaller "steps" between them, compared to a conventional four-speed automatic, which bolsters both performance and the feeling of smoothness. Shorter steps between the gears help the transmission quickly find the best gear for the vehicle speed and road conditions, with less back-and-forth hunting on grades - a trait that is particularly helpful when towing.
The smaller steps also enable a steep, 4.02:1 first gear, which provides an improved-performance launch feel. The two overdrive gears include a 0.85:1 ratio in fifth gear and a 0.67:1 ratio in sixth. With two overdrive gears, engine rpm is reduced by approximately 9 percent at 60 mph - a reduction to about 1,500 rpm. Lower engine rpm can bolster fuel economy because less fuel is used. A lower-rpm cruising speed also enhances smoothness and reduces noise heard in the vehicle's cabin.
Clutch-to-clutch operation
The 6L80's sophistication is exemplified by clutch-to-clutch operation that reduces complexity and packaging. It also enhances the performance feel of the transmission, as shifts feel more immediate and precise.
Clutch-to-clutch operation is achieved with three planetary gears, two stationary clutches and three rotating clutches. It is a simple, less complex design that enables the six-speed transmission to be packaged in a size not much larger than a four-speed automatic. Only the first-to-second upshift is a freewheeling action, where the second gear clutch engages while the first gear one-way clutch spins freely. This allows a greater degree of smoothness at lower vehicle speeds.
Internal controller and driver-selectable features
A new, 32-bit electro-hydraulic control module optimizes transmission performance according to a variety of vehicle inputs, while also enabling features including tow/haul mode, auto grade braking and manual range selection. The controller is located entirely within the transmission and operates while immersed in transmission fluid. Locating the controller internally shields the controller from outside elements.
Tow/haul mode is a driver-selectable feature that provides optimal shift characteristics specific for towing or hauling a heavy load. The feature is complemented by manual range selection, which allows the driver to block out upper gears and select desired gears for unique driving conditions, such as towing on a steep grade. The manual range selection feature increases the feeling of control by holding the gear pre-selected by the driver. Electronic safeguards prevent the transmission from being shifted in a manner that could cause engine damage or loss of vehicle control. Auto grade braking is available when the tow/haul mode is selected and the transmission is not in the range selection mode.
GM's first Hydra-Matic six-speed RWD 6L80 was initially introduced in the 2006 Chevy Corvette and Cadillac STS-V and XLR-V. For 2007, GM is offering the 6L80 in the 2007 Cadillac Escalade and GMC Yukon Denali SUVs. GM will produce more than one million six-speed automatic transmissions annually by 2008, and more than three million annually by 2010.
GM's Hydra-Matic 6L80 Six Speed Automatic Delivers Balanced Performance, Economy For Full-Size SUV's
* Manufactured at GM's Toledo, Ohio and Ypsilanti, Mich. manufacturing plants
* One of the most sophisticated transmissions in the industry with clutch-to-clutch operation
* Wide 6.04:1 ratio spread delivers excellent balance of performance and fuel economy
* Approximately 9-percent reduction in engine rpm at 60 mph (compared to the 4L60 four-speed transmission) for enhanced fuel economy and NVH characteristics
* Tow/haul mode and auto grade braking for optimal towing performance
* Manual range selection for driver-selectable performance
TOLEDO, Ohio - A new GM Hydra-Matic 6L80 rear-wheel drive six-speed electronically controlled automatic transmission designed for the performance requirements of trucks debuts in GM's 2007 full-size SUVs. It is one of the most technologically advanced transmissions in the industry, featuring clutch-to-clutch operation, manual range selection and an integrated 32-bit electro-hydraulic controller.
The 6L80 is available on vehicles equipped with the Vortec 6.2L V-8 engine. A wide, 6.04:1 overall ratio - including two overdrive gears - helps deliver an excellent balance of performance and fuel economy. It is similar to the six-speed "paddle shift" automatic transmission introduced on the 2006 Corvette, but has been tailored for the heavy-duty requirements of SUVs and trucks.
"There are no compromises with the Hydra-Matic 6L80 transmission - it delivers great performance and enables improved fuel economy on the highway, all with smooth, almost imperceptible operation," said Jeff Baran, chief engineer for six-speed rear-wheel drive transmissions. "Complementing its sophisticated performance characteristics is the tough capability necessary for the demanding duty cycle of trucks and the tasks their drivers ask of them."
The Hydra-Matic 6L80's six forward gears have smaller "steps" between them, compared to a conventional four-speed automatic, which bolsters both performance and the feeling of smoothness. Shorter steps between the gears help the transmission quickly find the best gear for the vehicle speed and road conditions, with less back-and-forth hunting on grades - a trait that is particularly helpful when towing.
The smaller steps also enable a steep, 4.02:1 first gear, which provides an improved-performance launch feel. The two overdrive gears include a 0.85:1 ratio in fifth gear and a 0.67:1 ratio in sixth. With two overdrive gears, engine rpm is reduced by approximately 9 percent at 60 mph - a reduction to about 1,500 rpm. Lower engine rpm can bolster fuel economy because less fuel is used. A lower-rpm cruising speed also enhances smoothness and reduces noise heard in the vehicle's cabin.
Clutch-to-clutch operation
The 6L80's sophistication is exemplified by clutch-to-clutch operation that reduces complexity and packaging. It also enhances the performance feel of the transmission, as shifts feel more immediate and precise.
Clutch-to-clutch operation is achieved with three planetary gears, two stationary clutches and three rotating clutches. It is a simple, less complex design that enables the six-speed transmission to be packaged in a size not much larger than a four-speed automatic. Only the first-to-second upshift is a freewheeling action, where the second gear clutch engages while the first gear one-way clutch spins freely. This allows a greater degree of smoothness at lower vehicle speeds.
Internal controller and driver-selectable features
A new, 32-bit electro-hydraulic control module optimizes transmission performance according to a variety of vehicle inputs, while also enabling features including tow/haul mode, auto grade braking and manual range selection. The controller is located entirely within the transmission and operates while immersed in transmission fluid. Locating the controller internally shields the controller from outside elements.
Tow/haul mode is a driver-selectable feature that provides optimal shift characteristics specific for towing or hauling a heavy load. The feature is complemented by manual range selection, which allows the driver to block out upper gears and select desired gears for unique driving conditions, such as towing on a steep grade. The manual range selection feature increases the feeling of control by holding the gear pre-selected by the driver. Electronic safeguards prevent the transmission from being shifted in a manner that could cause engine damage or loss of vehicle control. Auto grade braking is available when the tow/haul mode is selected and the transmission is not in the range selection mode.
GM's first Hydra-Matic six-speed RWD 6L80 was initially introduced in the 2006 Chevy Corvette and Cadillac STS-V and XLR-V. For 2007, GM is offering the 6L80 in the 2007 Cadillac Escalade and GMC Yukon Denali SUVs. GM will produce more than one million six-speed automatic transmissions annually by 2008, and more than three million annually by 2010.