ZF 8HP transmission

The ZF 8HP transmission is ZF Friedrichshafen AG's trademark name for its 8-speed automatic transmission models for longitudinal engine applications. The name is short for 8-speed transmission with hydraulic converter and planetary gearsets. Designed and first built by ZF's subsidiary in Saarbrücken, Germany, it debuted in 2008 on the BMW 7 Series (F01) 760Li sedan fitted with the V12 engine. BMW remains a major customer for the transmission.

Another major customer is Stellantis, who both received a license to produce the transmission and set up a joint-venture plant with ZF. Stellantis has built the transmission at its Kokomo Transmission plant since 2013 under their own brand name, the Torqueflite 8. The joint venture plant in Gray Court, South Carolina opened in 2012.

Layout
One of the main aims of the ZF 8HP transmission is to improve vehicle fuel economy with extra speeds. Compared to the six-speed ZF 6HP transmission it uses 12 % less fuel, and 14 % less than a 5-speed transmission. Due to changes in internal design, the shift times have reduced to 200 milliseconds; additionally, the unit brings the ability to shift in a non-sequential manner – going from gear 8 to gear 2 in extreme situations. In the 8HP 70 version, it has a torque handling limit of 700 Nm, and weighs 87 kg.

First generation 8HP products were released starting in 2010. In addition to the rear-wheel drive variant, two different four-wheel drive versions were available, with a version destined for Volkswagen Group applications using a Torsen centre differential. It is able to encompass a torque range from 300 Nm to 1000 Nm, and is available for use in middle-class cars through to large luxury sport utility vehicles.

Second generation 8HP products were released starting in 2014. Efficiency improvements over the original design and the first generation include a wider ratio spread of 7.81, reduced drag torque from the shift elements, reduction in required oil pump pressure, and broadened use of the coasting and start-stop systems. ZF estimated fuel economy improvement over first generation 8HP kits to be 3 %. Refinements were also made with respect to vibration.

Third generation 8HP products were released starting in 2018. Major improvements are total spread of 8.59 and a fuel economy improvement of 2.5 % compared to the second generation. There are several options in maximum torque available, also the gearbox is available with mild hybrid and plug in hybrid options: With 15 kW and 200 Nm supporting boosting and recuperation in combination with 48 Volt technology up to 90 kW and 250 Nm for usage with higher voltage.