Drive Range, Eighth Gear (Mechanical Powerflow): Notes

WARNING: This page is about a different variant/trim than selected.

Drive Range - Eighth Gear is used to maximize engine efficiency and fuel economy beyond Seventh gear calibrations. Input signals from the transmission speed sensors (input and output), throttle position (TP) sensor and other vehicle sensors, are used by the TCM to determine the precise moment to shift the transmission into Eighth gear. In Eighth gear, the planetary gear sets rotate in overdrive, providing a 0.747:1 gear ratio between the torque converter turbine and the front differential carrier assembly (238).

1. Power From The Engine

Torque from the engine is transferred to the transmission through the engine flywheel which is bolted to the torque converter assembly (14).

2. Turbine Shaft Driven

As the torque converter turbine rotates, the 5-7-reverse and 6-7-8-9 clutch housing (530) and the turbine shaft (547) which is splined to the torque converter turbine, is also forced to rotate at turbine speed.

3. Input Sun Gear Driving

The input sun gear (551), which is splined to the turbine shaft (547), drives the input carrier assembly (552) pinion gears.

4. 6-7-8-9 Clutch Assembly Applied

The 6-7-8-9 clutch plates (570-577), splined to the 5-7-reverse and 6-7-8-9 clutch housing (530) and the reaction carrier hub (532), are applied and drive the reaction carrier hub (532).

5. 3-8 Clutch Assembly Applied

The 3-8 clutch plates (510-514, 535, 536), splined to the 3-8 and 5-7-reverse clutch hub (534) and the transmission case (19), are applied and hold the 3-8 and 5-7-reverse clutch hub (534) stationary.

6. Overdrive Carrier Driving

The overdrive carrier (546) large pinion gears are driven around the stationary 3-8 and 5-7-reverse clutch hub (534) and over drive the overdrive internal gear (output carrier assembly) (555).

7. Input Carrier Assembly Driven

With both the input internal gear (overdrive carrier assembly) (546) and the input sun gear (551) driving at converter turbine speed, the input carrier pinions act as wedges to obtain direct drive to obtain direct drive to the output internal gear, which drives the output carrier assembly (555) pinions.

8. Output Carrier Assembly Driving

The output carrier assembly (555) is splined to and drives the output carrier transfer drive gear hub (502).

9. Output Carrier Transfer Drive Gear Hub Driven

The output carrier transfer drive gear hub (502) is splined to and driven by, the output carrier assembly (555).

10. Drive Sprocket Driving

The drive sprocket (234), splined to and driven by the output carrier transfer drive gear hub (502), drives the drive link (233) which drives the driven sprocket (241).

11. Driven Sprocket Driven

The driven sprocket (241), driven by the drive link (233), is splined to the front differential carrier sun gear (240).

12. Front Differential Carrier Sun Gear Driving

The front differential carrier sun gear (240), is in mesh with and drives, the front differential carrier (238), thus transferring power to the front differential carrier and to the drive axles.