Transmission and Driveshafts
Component Layout – Transmission
Component Layout – Driveshafts
The vehicle features a single speed transmission, located in the rear, connected to the LH side of the motor and mechanically connected using a splined drive coupler. The transmission is connected to the rear road wheels via the two unequal length driveshafts. An internal parking pawl, located on the input shaft, is electrically connected to the Transmission Control Module (TCM) located on the underside of the trunk assembly.
| Description | Specification |
| Transmission ratio | 8.2752:1 |
| Speed | 14,000 RPM |
| Transmission fluid | Any brand of ATF meeting ATF Dexron VI specification |
The transmission casing is constructed in three main sections, each cast from aluminum. The casing features a top fill plug, a side service fill/level plug and a drain plug.
A splined, electrically isolated drive coupler connects the splined output shaft on the motor to the splined input shaft on the transmission. A metal snap ring locates the drive coupler on the input shaft. The drive coupler is constructed from metallic and non-metallic materials to electrically isolate the motor from the transmission.
The transmission incorporates an internal, gear driven oil pump which is connected to the base of the transmission casing via an internally housed scavenge pipe. The scavenge pipe utilises a filter, made from a wire mesh, to prevent solid contaminants from contacting the gears and bearings. An oil feed pipe connects the oil pump to the gears and bearings.
The differential is of conventional design with a differential housing bolted to the final drive gear. The housing supports the differential pin, planetary and sun gears. The differential assembly is supported in the transmission assembly using deep groove ball bearings.
The parking pawl is located on the input shaft. When the wheel speed is at or near zero and the key is removed from the ignition, the parking pawl actuator engages on the park wheel, locking the transmission. The transmission harness connects the Transmission Control Module (TCM) to the parking pawl using a ten pin connector.
The gear selector uses optical switches that are interrupted by an opaque flag attached to a lever. The selector incorporates detents for each gear and moves in a R, N, D layout. Each gear has a separate optical switch that drives a separate line to the PEM controller. Thus, there are three gear select lines between the actuator and the Power Electronics Module (PEM) controller: reverse, neutral and drive.
NOTE: An audible tone will be heard when reverse is selected.
The unequal length driveshafts feature a Constant Velocity (CV) joint at both ends, each with a rubber boot to protect the joint from contamination. The outer CV joint features external splines which locate into the internally splined drive flange. The externally splined inner CV joints locate in the internally splined transmission output shafts. A non-servicable driveshaft seal is fitted to the transmission casing on each side to seal the casing and prevent the ingress of dirt and moisture.
There is no mechanical linkage between the gear selector and the transmission. The transmission gearset is always in constant mesh. There is no mechanical neutral or reverse gear. Reverse drive is achieved by reversing the direction of rotation of the motor, neutral is achieved by de-energizing the motor. The gear selector commands motor drive state and has no connection with the transmission. It is possible to select any gear position at any time; however, inappropriate gear selections will be prevented until the required conditions are met:
NOTE: This behavior is also applicable from reverse to drive.
The Transmission Control Module (TCM) controls the operation of the parking pawl. When the vehicle speed is at or near zero and the key is removed from the ignition, the TCM will engage a parking pawl lock to prevent the transmission (and rear wheels) from rotating. This lock is disengaged when the brake pedal is depressed and the key is moved to the START position.
When neutral is selected by the gear selector, the vehicle will transition into electrical neutral will command zero torque to the motor and the PEM will enter standby mode.
If the vehicle has been in Neutral for more than 1 second and the vehicle is moving at less than 5 mph, the brake pedal must be depressed in order to enter Drive or Reverse. If the vehicle has been in Neutral for less than 1 second or the vehicle is travelling faster than 5 mph, gear selections will be allowed if the gear choice meets the criteria for a valid selection. If the vehicle is in Drive or Reverse and the throttle pedal is not depressed, a fixed amount of torque will be commanded to maintain a creep effect similar to vehicles with automatic transmissions. In cases in which the user’s selection is denied, an audible alert will sound, the touch screen will display an error screen and the gear selected will flash on the instrument pack. The user will have to return the gear selector to Neutral before being allowed to attempt the select again. If a gear is selected while the throttle pedal is depressed and the vehicle is already moving in the selected direction at a speed greater than 5 mph, torque will be steadily increased to match the throttle pedal position once the gear selection has been completed.
If the drive gear is selected when the wheel speed indicated the vehicle moving more than 5 mph in the reverse direction, the gear selection will be denied. If the vehicle is in the drive gear, torque will be limited to avoid exceeding the motor’s maximum speed.
Reverse is achieved by reversing the direction of motor rotation. The touch screen will sound a single audible alert whenever the vehicle enters reverse and maximum speed is limited to 15 mph. If reverse is selected when wheel speed indicates the vehicle speed is greater than 5 mph in forward direction, the gear selection will be denied.
The traction control system reduces motor torque to reduce rear tire slip during acceleration and deceleration. Traction control operates by comparing front tire speed, as measured by the front wheel-speed sensors of the Anti-lock Braking System (ABS), to rear tire speed, as measured by motor speed and transmission gear or as measured by rear wheel speed sensors of the ABS system. Traction control is automatically enabled every time the vehicle enters Drive. The vehicle will monitor wheel speed and control traction power to minimize wheel slip.
Unrestricted drive torque will be available when:
Drive torque is restricted but available if:
NOTE: Prior to total loss of torque, the user will be informed via the touch screen as torque progressively limits.
Drive torque will be restricted to zero torque (though not always immediate) when :
NOTE: The touch screen will appropriately alert the user why torque is disabled.
NOTE: The vehicle cannot be started if the driver's seatbelt is not securely fastened.
NOTE: A failure of the ABS system disables the traction control system. A notification will be displayed on the touch screen.
The g-rotor style pump is mechanically driven by the transmission intermediate shaft and only functions correctly during normal forward motion of the vehicle. The design allows for short periods of reverse driving without pumped oil supply being active.
Oil is scavenged from the base of the transmission casing via a scavenge pipe and distributed to the gears and bearings. The scavenge pipe strainer, made from a wire mesh, to prevent solid contaminants from contacting the oil pump, gears and bearings. Following lubrication of the gears and bearings, any excess oil drains back to the base of the transmission casing.
The parking pawl is engaged when the key is removed from the ignition switch and the vehicle is stationary and disengaged when the key is inserted. The pawl is engaged when the vehicle is being charged. The pawl will not release prior to completion of pre-charge.
The differential allows the road wheels to turn at different speeds whilst providing an equal amount of torque. The integral gear on the output shaft meshes with the final drive gear on the differential assembly. When the output shaft rotates and the wheels are travelling at the same speed, torque is applied to the complete assembly; the planetary gear does not rotate. Torque is transmitted to the road wheels through the drive shafts.
During cornering, the inner wheel travels a shorter distance at a lower speed. This results in the planetary gear rotating about the outer wheel gear, therefore increasing the speed of the outer wheel.