The ZF8HP automatic transmission is one of the most popular: installed on medium and large engine cars, its excellent reliability is a guarantee for manufacturers. There are several versions of this gearbox whose difference, on a structural level, allows to withstand more or less torque depending on the model.
In the case of BMW, in this specific release we have: ZF8HP45: maximum torque 450Nm for petrol versions, 500Nm for Diesel versions
The main prerogative of this gearbox is that it totally differs from a «traditional» transmission, because the various gears are managed by epicycloidal groups, particular elements composed of 3 components: sun gear, planetary carrier (and gears) and ring gear.
Every single group is alternated by clutch groups, which allow, by braking these components, to switch between one ratio to an another by combining the various planetary groups. To ensure that the gear change takes place, there is an electronic management that acts on the solenoid valves that make these clutch groups move, in order to switch between one gear and another.
The greater the speed with which these clutches are moved, the greater the shifting speed is and the less the gearbox will be smooth.
To improve the performance of this gearbox, it is possible to modify the torque parameters, the time maps — which act on the clutch packs — making shifting less comfortable as the shifting times decrease — and the shifting speeds.
Thanks to the new boot and bench mode protocols you will be able to intervene on this transmission by carrying out repairs as well as optimizing the operating parameters of this gearbox. Adjust the torque limitations, the shift timing parameters and the shift points to make it even faster and more efficient at each gear shift!