Designed and built by GM, the 8L45 transmission speed is expected to contribute up to 5-percent greater efficiency, when compared to the previous Hydra-Matic6L45 and 6L50six-speed automatictransmissions. Smaller steps between gears compared to the 6L45/6L50 six-speed automatics enable a wide 7.0 ratio spread andkeepthe engine within the sweet spot of the rpm band, making the most of its horsepower and torque to optimize performance and efficiency.
Like its more potent8L90 variant,the8L45 occupies the same space as GMs previous6L45 and 6L50six-speeds while weighing less. Comparedto the 8L90, the 8L45 issmaller and lighterwhile having thesame grouping of four gearsets and five clutches. The8L45 also incorporates special components necessary for engines withstart/stoptechnology.
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One of the major changes ofthe 8L45 compared tothe 8L90 isthe gear ratios. With a wide 7.0 overall gear ratio and numerically higher 4.62 first gear, the 8L45 will help drivers start off more confidently, with a greater feeling of immediate performance. The gear ratios and smaller steps between gears also result in a 5 percent fuel economy benefit over a six-speed automatic.
For performance driving, the transmission offers full manual control via steering wheel paddles, and unique algorithms to deliver notableshift performance with the smoothness and refinement that comes with a conventional automatic fitted with a torque converter.
At this point, GM has not officially confirmed the torque capacity of the 8L45 M5N. However, we should note that 8L45 M5U, the more capable variant of the 8L45, has a torque capacity of 738 pound-feet (1000 Nm). In addition, the 8L45 is estimated to be roughly 33 pounds lighter than the 8L90.
Compact And Lightweight
Featuring four gearsets and five clutches, creative packaging enables the 8L45 to fit the same space as the previous 6L45/6L50 family of six-speed automatics. Being less capable than the 8L90 also enables the8L45 to be33pounds (15 kg) lighter. Along with design features that reduce friction, the 8L45 is expected to contribute up to 5-percent greater efficiency, when compared with a six-speed automatic.
Five clutches are used, three at a time, leaving only two open clutches in each gear state. Optimized clutch sizing and off axis binary pump contribute to outstanding spinloss attributes.
All applications feature adaptive shift controls. Several features such as grade braking, Performance Algorithm Shifting, and Driver Shift Control are available on some of the applications. Performance Algorithm Shifting (PAS) monitors how assertively the driver is using engine output and other vehicle sensors to determine at what engine speed to upshift of downshift. Driver Shift Control allows the driver to shift the transmission like a clutchless manual gearbox. Electronic safeguards prevent over-revving if the wrong gear position is selected.
The 8L45 uses VFS control components to monitor clutch pressures with optimum accuracy. The result are faster and more precise shifts.
The 8L45s 32-bit transmission control module (TCM) monitors transmission performance and compensates for normal wear in components such as clutch plates, so performance is consistent for the life of the transmission. The control module also tests the components to optimize their interaction on an on-going basis.
The 8L45s controller analyzes and executes commands,the processor microcontroller executes instruction at a rate of 120 Million Instructions per second, and wide-open-throttle upshifts are executed up to eight-hundredths of a second quicker than those of the dual-clutch transmission offered in the Porsche 911.
The torque converter is 258 mm in diameter and features a lock-up clutch, although clutch and converter specifications vary depending on the application. The 8L45 uses electronic http://cwtrans.com.au/
