8HP is ZF Friedrichshafen AG's trademark name for its eight-speed automatic transmission models for longitudinal engine applications, designed and built by ZF's subsidiary in Saarbrücken. It had its debut in the BMW 7 Series 760Li saloon fitted with the V12 engine, and since then each new BMW model in all Series down to the 1 Series in rear-wheel-drive and all-wheel-drive versions have been equipped with it. One of its main aims is to improve vehicle fuel economy, and it can achieve an 11% saving compared to the ZF 6-speed transmission and 14% versus modern 5-speed transmissions. 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 8HP70 version, it has a torque handling limit of, and weighs. Future development will see two four-wheel drive versions available, with a version destined for Volkswagen Group applications using a Torsen centre differential. It will be able to encompass a torque range from to, and will be available for use in middle-class cars through to large luxury sport utility vehicles. Chrysler Group LLC initially received the 8HP 8-speed automatic transmissions from the ZF plant in Saarbrucken, Germany. By 2013, in parallel with Chrysler Group, ZF had set up a new transmission production plant in Gray Court, South Carolina. ZF Friedrichshafen and Chrysler Group have reached a supply and license agreement for the 8HP. Chrysler Group is licensed to produce the 8HP at the company’s Kokomo Transmission Plant and the Kokomo Casting plant, production began in 2013. This transmission is marketed by Chrysler under their own brand name, the Torqueflite 8. 2nd generation 8HP products were released starting in 2014. Efficiency improvements over the original design include a wider ratio spread of 7.8:1, 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 1st generation 8HP kits to be 3%. Refinements were also made with respect to vibration. 3rd generation 8HP products were released starting in 2018. Major improvements are total spread of 8.6 and a fuel economy improvement of 2.5% compared to the 2nd 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.
Specifications
Preliminary Note
Below is a table of reference gear ratios as provided with the ZF 8HP transmission, though actual implementations may differ depending on the tuning and specifications of individual vehicle manufacturers such as BMW and Audi. Differences in gear ratios have a measurable, direct impact on vehicle dynamics, performance, waste emissions as well as fuel mileage.
