News - Fiat
High-tech nine-speed auto for Fiat’s small crossover
FCA nine-speed transmission to trickle down to Fiat 500X crossover
10 Mar 2015
By TIM ROBSON in TURIN
UPDATED: 11/03/2015AUSTRALIA will get another taste of ZF’s revolutionary new nine-speed automatic transmission – and at a keener price point – when the Fiat 500X debuts in August.
Fiat Chrysler Automobiles (FCA) has specified the German-made unit for its 500X/Jeep Renegade double act, with the latter scheduled to arrive in October – some two months after the Fiat city SUV.
It will complement the brand’s Jeep Cherokee range, which also offers the innovative gearbox as an upgrade across its range.
Paired with an all-wheel-drive system that relies on electronic rather than mechanical actuation, the nine-speeder will be offered in the 500X’s two highest grades, Lounge and Cross Plus.
The nine-speeder first saw service in Range Rover’s Evoque in late 2013, before appearing in Cherokee last year.
The gearbox is built in the US by Chrysler, under licence from ZF.
The 9HP transmission is claimed to provide fuel savings of up to 16 per cent over the more common six-speed automatic, thanks to its narrower gear steps and taller final ratio of 9.81:1.
A sophisticated electronic control unit also allows the gearbox to skip multiple gears where needed, as well as facilitate the use of automatic engine idle-stop technology from the car’s own onboard systems.
Specific to front-transverse engine-mounting applications, the 9HF is surprisingly compact, and weighs 86kg – 6kg less than ZF’s six-speed front-transverse auto.
It is equipped with four cog-sets that are ‘nested’ together, a pair of positive-engagement dog clutches in place of more traditional clutch packs and a traditional torque converter.
The nested gear-sets give the 9HP its compact dimensions, allowing it to be used in compact SUVs, sedans and hatches. It is only 6mm longer than the six-speed auto it replaces.
Its peak torque value is 480Nm for petrol engines and 450Nm for diesel units, allowing it to be used across a variety of smaller cars.
Known for its rear-wheel drive transmissions that are seen in vehicles including the Ford Falcon, ZF took the technology from its latest eight-speed RWD transmissions and applied it to an all-new front-wheel-drive product.
“There’s a growing percentage of vehicles that are looking for alternate transmissions, and that’s why ZF have pursued the front-wheel drive,” said technical services manager of ZF Services Australia, Shane Trenbath.
“There is still a place in the modern drivetrain for a ‘traditional’ automatic.”“A dual clutch has got some very good features, such as its ability to shift very quickly, but you can’t compare it to a conventional auto,” said Mr Trenbath.
“There is definitely a place for both. A dual-clutch transmission is good in a performance type vehicle, but the smoothness and the comfort of a traditional automatic is hard to beat, especially if you can achieve good efficiency from it.”
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