Chrysler Group has
announced that the much-needed new ZF-sourced
eight-speed automatic transmission is now set to make
production debut on the Model Year 2012 Chrysler 300 and
its platform sister, the Dodge Charger, as well as in
Lancia's rebadged version of the former model. It will
also mark the debut of an 8-speed automatic transmission
in a North American manufactured vehicle.
The new eight-speed automatic, introduced and licensed
through ZF and often found on high-end luxury cars
including Audi, Bentley, BMW, Range Rover and Rolls
Royce, will be available on selected models of the 300
and Charger. With the newly facelifted 300 and Charger
currently seeing their sales down year-on-year versus
pre-facelift versions, the new transmission option
should give the models a useful fillip.
transmission will be only mated to the 3.6-litre V6
"Pentastar" engine that was introduced last year. The
8-speed auto will debut under the bonnet of Lancia's
Thema at this month's Frankfurt IAA when the production
version is launched.
rear-wheel-drive platforms there are presently only a
few future uses within the Fiat Group for the new ZF
transmission. As well as being fitted to the Pentastar
V6-powered version of Lancia's newly rebadged Chrysler
300 sedan it will also be fitted to the VM Motori-equipped
diesel Thema in the future. It may also appear on
Maserati's future "Baby Quattoporte" sedan, which will
be based on the 300/Charger platform.
The result is a four mile-per-gallon increase on the
300/Charger that will push highway fuel economy to an
EPA-rated 31 mpg for the Model Year 2012 Chrysler 300
and 2012 Dodge Charger – up from 27 mpg highway over
last year’s model. The transmission efficiency and wide
ratio spread also provide the better fuel economy in
city traffic. Fuel economy for both models is 19 mpg on
the EPA city cycle - an increase of five percent over
last year’s five speed automatic. With eight speeds,
driving at a lower rpm in both city and highway
environments also effectively helps reduce emissions by
nearly 11 percent on both vehicles.
All-wheel-drive variants of the transmission will also
be available on both models for the 2012 Model Year.
Designed as a modular transmission, the 845RE allows for
the addition of Chrysler’s all-wheel drive system. This
all-wheel drive is engaged only when needed, requires no
driver input and helps improve fuel economy by only
engaging the front-drive wheels when there is excessive
Compact and lightweight, the new transmission required
no structural changes to either vehicle and despite the
addition of more gears, the transmission actually weighs
just 3kg more than the outgoing five speed automatic
transmission. Coupled to the new rear-wheel-drive
automatic is a differential with final drive ratio of
2.65:1. The transmission efficiency and gear ratio
spread enable spending more time at lower engine rpm and
the use of numerically low axle ratios further improve
highway fuel economy. All-wheel-drive models are
equipped with a 3.07;1 final drive ratio.
Fully electronic and aided with software that provides
an adaptive shifting strategy, the 845RE has been
designed to provide optimal shifting characteristics
consistent with the Chrysler and Dodge brands. Adaptive
shifting takes into account a number of variables
including engine torque gradients, kick down,
longitudinal and lateral acceleration, hill detection,
friction detection and downshift detection in
determining shift patterns. Additional parameters
include vehicle speed control, electronic stability
control activation and high temperatures that can affect
The addition of more gear ratios in the transmission
helps reduce the gaps normally associated with
upshifting and downshifting. Both vehicles benefit from
nearly imperceptible gear changes due in part to very
evenly spaced gear steps between each gear ratio. The
gear steps also are very small providing quicker
acceleration and smoother shifts.
High efforts in shifting also have been eliminated with
gear selection controlled by a shift-by-wire system. The
position selected by the driver (P, R, N, D) is
transmitted electronically with no mechanical linkage
from the shifter to the outside of the transmission.
Elimination of this linkage removes any shift effort
from the driver’s gear selection. Shift-by-wire also
allows improved calibration and smoothness of garage and
parking lot shifts.
All shifts, whether single, double or multiple are
performed as a direct result of the pedal position.
Downshifts are made with very short response times and
lead directly to the requested gear. Multiple upshifts
can be decoupled temporarily if the torque request
changes during the upshift. This helps eliminate the
shift searching of the transmission.
During more spirited driving conditions, sporty, quick
shifts are possible as a result of multiple parameters
either through a Sport shift mode that requires simple
driver input. At the rear of the shifter is a gate that
allows for down- and up-shifting by the driver. Once the
vehicle is in the Sport mode, the driver can use either
the console-mounted shifter or a pair of paddle controls
located on the steering wheel.
Once the Sport mode is selected, shift times are quicker
and engine rpm is allowed to increase for a more
performance- oriented acceleration and higher shift
dynamics. Acceleration times for the Dodge Charger and
Chrysler 300 for 0-to-60 mph are 7.2 seconds.
Internally, the 845RE transmission features four gear
sets and five shift elements (multi-disc clutches and
brakes) inside the transmission. With fewer open shift
elements, drag losses due to multiple parts rotating
relative to one another, are reduced. Additionally,
lower viscosity transmission fluid is used resulting in
improved transmission efficiency and fuel economy
improvements especially during cold environments or
vehicle start-up. The 845RE also is “fill for life” not
requiring oil changes during normal driving conditions.
The all-new automatic transmission will initially be
purchased through ZF. Production by Chrysler at its
Kokomo transmission facility under license by the
German-based company is slated following introduction.
8HP70 8-Speed Automatic