Transmission Description - TDV8 4.4L Diesel (G2284451): Overview

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

The ZF 8HP76 transmission is an electronically controlled, hydraulically operated, 8 speed automatic unit. The ZF 8HP76 transmission is similar in design to the ZF 1st generation 8HP70, but has the following major differences:

Disc separation

Wave springs integrated within the transmission shift elements allow for improved drainage of ATF (automatic transmission fluid) back to the transmission sump, which reduces drag across open shift elements for improved efficiency.

Spool valve mechatronic

Increased use of the finer tolerance spool valves in place of 8HP Gen 1 transmission poppet valve technology improves the efficiency of the transmission hydraulic circuit.

90% mechanical vane pump

The mechanical vane pump is a comparable technology to the 8HP Gen 1 transmission, with a reduced pump volume. The smaller pump volume reduces pumping losses whilst still meeting the pressure demand due the improved hydraulic circuit efficiency due to increased use of spool valve technology.

Optimised brake B

A new piston design offers increased controllability for higher shift quality, as well as improved drainage of ATF back to the transmission sump, which reduces drag across open shift elements for improved efficiency.

Wider ratio spread

The new transmission ratios are better matched to customer demands for improved low speed ascent vehicle capability and improved vehicle efficiency.

The ZF 8HP76 transmission has the following features:

Designed to be maintenance free.
Automatic Transmission Fluid (ATF) 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 Transmission Control Module (TCM).
Adaptive Shift Strategy (ASIS), 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 Powertrain Control Module (PCM) via the FlexRay systems bus for communications.
Default mode if major faults occur.
Diagnostics available from the TCM via FlexRay.

On vehicles featured with the stop/start system, the 8HP76 automatic transmission is fitted with a Hydraulic Impulse Storage (HIS) device to ensure pressurized Automatic Transmission Fluid (ATF) is available to the shift elements as quickly as possible when the engine is started.

The transmission selections are made using the linear Transmission Control Switch (TCS) in the floor console.

For additional information, Refer to: EXTERNAL CONTROLS