Hydra-Matic 4T40-E/4T45-E (MN4/MN5)
2005 Model Year Summary
- Driver Shift Control Available For Additional Applications
- New Application In Pontiac G6 and G6 GT
- New Applications in Saturn ION and VUE
- New Application in Chevrolet Cobalt
- Bosses Added For Stiffness
- Detent Lever Modified For Reduced Shift Effort
- New Pass-Through Electrical Connector
FULL DESCRIPTIONS OF NEW OR CHANGED FEATURES
DRIVER SHIFT CONTROL ADDED
The Pontiac G6 GT application gets the driver shift control (DSC) feature that allows manual shifting of the transmission. The floor-mounted shift lever can be moved rearward and to the right to enable DSC, and momentary movements of the lever forward and rearward can respectively upshift and downshift the transaxle. Electronic controls prevent downshifting at speeds which would cause the engine to over-rev, and automatically downshift to 1st gear when the vehicle comes to a stop.
The 2004 model year 4T45-E implemented a modified channel plate and valve body which enables all 4 gears to be selected in the 5th / DSC range position. It was used in the 2004 Chevrolet Malibu to enable manual range selection (Low, D2, D3) using buttons mounted on the side of the shifter. In 2005, an additional L4 range selection was added to enable 4th gear operation with the shifter mounted buttons.
NEW APPLICATION IN PONTIAC G6 AND G6 GT
The 4T45-E is used by the new Pontiac G6, mated to the LX9 3.5-liter V-6. The G6 sedan uses a 3.05 final drive ratio and the G6 GT gets the 3.29 final drive ratio The G6 GT also features Driver Shift Control (DSC), and a torque converter that allows more torque multiplication for quicker acceleration.
NEW APPLICATIONS IN SATURN ION AND VUE
The Saturn ION and VUE use the 4T45-E mated to the Ecotec L61 2.2-liter L4.
NEW APPLICATION IN CHEVROLET COBALT
The Cobalt will use the 4T45-E with two final drive ratios, for the standard Ecotec L61 2.2-liter L4 and the optional Ecotec 2.4-liter L4, which has a higher ratio for quicker launch and acceleration (see specifications.)
BOSSES ADDED FOR STIFFNESS
On the 4 cylinder applications, bosses are added to the case to allow fasteners to attach to stamped brackets connected to the engine oil pans. This increases driveline stiffness which results in reduced noise and vibration.
DETENT LEVER MODIFIED FOR REDUCED SHIFT EFFORT
The detent lever profile is modified to provide lower shift effort when shifting out of Park position, and to create more uniform efforts in all of the quadrant positions of the shift lever.
NEW PASS-THROUGH ELECTRICAL CONNECTOR
The transmission pass-through wiring connector is modified with a second locking tab to improve the connection integrity and reliability. This is a 20-way electrical connector.
LOW MAINTENANCE
The transaxles use DEXRON III fluid, and are "fill-for-life", with no maintenance scheduled for normal operation.
OVERVIEW
The Hydra-Matic 4T40-E and Hydra-Matic 4T45-E are electronically controlled four-speed transaxles with low noise, high durability and smooth shifting resulting from sophisticated electronic controls integrating operation with the engine. The 4T45-E is a variant of the 4T40-E, added in 1999 to handle higher engine torque. Most of the robust components developed for the 4T45-E are now incorporated in both transaxles. Since 1999 continual development has improved durability and reliability of operation.
The 4T40-E received GM's proprietary Electronic Controlled Capacity Clutch in 1997 on 3.1-liter V-6 applications, and in 1998 all 4T40-E transaxles, and in 1999, all 4T45-E transaxles received the ECCC technology. ECCC allows a very small degree of controlled slip in the torque converter lockup clutch to dampen drivetrain pulses and contribute to smooth delivery of power. Driver Shift Control was added in 2004 to the Malibu application, which also received specific driveline mounting bosses.
Both transaxles' low-noise operation is a result of the high helix angle gears, an enclosed bell housing, and the random-pattern chain. Mass has been reduced through optimized case design and use of lightweight materials.
Continual upgrading for durability and drivability has taken place during the lifetime of the 4T40-E and 4T45-E, including increased capacity bearings, and hydraulically tuned clutch engagements.
