From the TRX Hellcat to the DB11, ZF’s ‘8HP’ Transmission Conquered the World
This ZF 8HP eight-speed automatic is going down in history. The incredible diversity of its applications is unprecedented, especially in the modern era. In fact, there are few complex automotive components that have been used in as many makes and models as ZF’s 8HP automatic transmission. Seriously. The only components as widespread are pretty much Saginaw steering boxes, Dana axles, and the ZF 8-speed automatic.
It’s incredible that you can find the same transmission in a Ram 1500 TRX with its Hellcat engine and an Aston Martin DB11. This transmission gets dropped in China Motor Company’s compact SUVs and Rolls Royces’ Phantoms. The ZF 8HP has taken over the world, for an intriguing reason.
ZF Friedrichshafen AG is headquartered in southern Germany, near both Switzerland and Austria. It began making gears for Zeppelin airships in 1915. It has the distinction of pioneering a six-speed manual transmission in 1920, fully synchronized transmissions in 1953, the first five-speed automatics in 1991, the first six-speed automatics in 1999, an early eight-speed automatic in 2007, and the first nine-speed automatic in 2011.
The company’s six-speed automatic was popular because it was simple and reliable. The only reason ZF bothered to add two more gears was for fuel savings. It managed to cut shift times to 200 milliseconds while dropping the unit’s weight to 192 pounds. That’s some incredible engineering. The result uses 12% less fuel than ZF’s old six-speed automatic. It’s light weight and quick shifts also made it a great candidate for performance applications. ZF later built 4WD and AWD versions. It even built an 8HP with beefier internals for high power applications such as supercars and Hellcat-powered SUVs and trucks.
Ram trucks has such faith in the 8HP’s durability, it tells 1500 buyers that they won’t need to change the transmission fluid even once, no matter how long they drive their trucks. One 2019 Ram 1500 owner’s already put 200,000 miles on his 8HP with no trouble.
Another one of ZF’s innovations is that the 8HP doesn’t have to shift through every gear sequentially. In many applications, some gears are for upshifts, while other gears are exclusively for downshifts. This is why later 10-speed transmissions are rarely more efficient (except when towing). It remains to be seen whether they justify the added complexity: the ZF 8HP may prove the high point of internal combustion transmission engineering.
Some standout vehicles with the ZF 8HP include the Aston Martin Rapide, Jeep Grand Cherokee Trackhawk, diesel Porsche Cayenne, and Lamborghini Urus. This transmission became so wildly popular that Chrysler Corporation and ZF collaborated to open another factory in Kokomo, Indiana. There, the 8HP is built under license and badged as the “Torqueflite 8.”
Here’s the list of automakers that have used the ZF 8HP:
- Audi
- Volkswagen
- BMW
- Porsche
- Chrysler
- Dodge
- Jeep
- Wagoneer
- Ram trucks
- Land Rover
- Jaguar
- Aston Martin
- Rolls Royce
- Bentley
- Morgan
- Alpina
- Ineos
- Alfa Romeo
- Maserati
- Lamborghini (Urus only)
- Jangling Motors
- China Motor Corporation/Mitsubishi
- Haval
- Great Wall Motors
- VinFaast
- Toyota (GR Supra only)
Read the secret behind the ZF 8 speed’s efficiency, or see how this transmission works in the video below:
