BMW 3 Owners & Service Manuals

BMW 3: Introduction

The automatic transmission GA8P75HZ of the G20 PHEV, which is based on the transmission introduced in the F07 at the end of 2009 (GA8HP70Z), is also manufactured by ZF.

If you have already taken part in the training for the 2nd generation of BMW ActiveHybrid vehicles, you will already be familiar with the GA8P70HZ transmission used there. The structure of the automatic transmission GA8P75HZ of the G20 PHEV is similar.

Automatic transmission
GA8P75HZ transmission

Structure and function


In order to satisfy the requirements of a Plug-in Hybrid Electric Vehicle, the automatic transmission was adapted. For this purpose, some existing components have been modified or replaced with other components. A part of the damping system was also extracted from the transmission area and connected to the combustion engine as a dual-mass flywheel with integrated centrifugal pendulum.

The connection to the transmission is effected via a spline.

As a result of the larger electrical machine and the additional torsional vibration damper, the housing of the GA8P75HZ transmission was extended by 30 mm in comparison to the GA8P70HZ transmission.

The hybrid area in the GA8P75HZ transmission can be divided into 5 components:

  • Dual-mass flywheel
  • Additional torsional vibration damper
  • Separation clutch
  • Electric motor
  • Electrical transmission oil pump for supplying oil pressure when transmission input shaft is idle.

Like on the GA8P70HZ transmission, the multidisc brake B is also reinforced in the GA8P75HZ transmission by increasing the diameter and number of discs and is equipped with actively controllable transmission oil cooling. This is necessary as, in addition to its function as a shift element, it must also enable the vehicle to start-up and crawl.

Automatic transmission
GA8P75HZ transmission

  1. Dual-mass flywheel (including torsional vibration damper and centrifugal pendulum)
  2. Additional torsional vibration damper
  3. Separation clutch
  4. Electric motor
  5. Multidisc brake B
  6. Electrical transmission oil pump

The transmission power flow of the GA8P75HZ transmission shows how the new components have been integrated in the automatic transmission.

Automatic transmission
Schematic structure of the GA8P75HZ transmission

  1. Torsional vibration damper
  2. Centrifugal pendulum
  3. Additional torsional vibration damper
  4. Electric motor
  5. Gear set 1
  6. Gear set 2
  7. Gear set 3
  8. Gear set 4
  9. Mechanical transmission oil pump
  1. Multidisc brake A
  2. Multidisc brake B
  3. Multidisc clutch C
  4. Multidisc clutch D
  5. Multidisc clutch E

  K0. Separation clutch


     Dual-mass flywheel

    In order to reduce fuel consumption and CO2 emissions, high-charged engines are used, the number of cylinders is reduced and the drivable speeds are lowered. However, with these measures the torsion

     Shift elements

    Brakes and clutches are described as shift elements which make possible the shifting and changing of all gears. Like in the GA8HP70Z transmission, the following shift elements are also used in the G

     Oil supply

    The basic functions of the oil circuit of the GA8P75HZ transmission correspond to those of the GA8HP70Z transmission. The oil has the following tasks: Lubrication Control of the shift elements Co


     Equipotential bonding

    The low-resistance connection between the housing of the high-voltage battery unit and ground is a crucial prerequisite for the fault-free function of the integrated isolation monitoring. This is why it is important to observe the correct tightening torque for all assembly screws. It is also impo

     Idle state

    Concept If the vehicle is in idle state, it is switched off. All power consumers are deactivated. General information The vehicle is in idle state prior to opening from the outside and after exiting and locking. Safety information Warning An unsecured vehicle can begin to move and possibly roll awa

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