Transmission Description (G2257823): Overview
The ZF 8HP70 transmission is an electronically controlled, hydraulically operated, 8 speed automatic unit. The hydraulic and electronic control elements of the transmission, including the TCM (Transmission Control Module), are incorporated in a single unit located inside the transmission and is known as 'Mechatronic'.
The ZF 8HP70 transmission has the following features:
- designed to be maintenance free
- ATF (Automatic Transmission Fluid) is 'fill for life'
- the torque converter features a controlled slip feature with electronically regulated control of lock-up, creating a smooth transition to the fully locked condition
- shift programs controlled by the TCM
- ASIS (Adaptive shift strategy), to provide continuous adaptation of shift changes to suit the driving style of the driver, which can vary from sporting to economical
- connected to the ECM (Engine Control Module) via the HS (High Speed) CAN (Controller Area Network) powertrain systems bus for communications
- default mode if major faults occur
- diagnostics available from the TCM via the HS CAN powertrain systems bus.
The higher fuel efficiency of the ZF 8HP70 automatic transmission is mainly due to the following modifications:
- A wider ratio spread and more gears for better adaptation to ideal engine operating points
- Significantly reduced drag torque in the shift elements (only two open shift elements per gear)
- Use of a more efficient ATF pump (double-stroke vane pump)
- Decoupling of the transmission when the vehicle is at standstill
- Improved torsion damping in the converter.
The transmission selections are made using the linear JaguarDrive TCS in the floor console. For additional information, refer to: EXTERNAL CONTROLS .
The V6 3.0L S/C Petrol engine features stop/start technology on some models. To complement this, the 8 speed transmission, on vehicles with stop/start technology, is fitted with a HIS (Hydraulic Impulse Storage) device to ensure ATF is available to the shift elements as quickly as possible when the engine is started.