The first twin-clutch from the 956
racer and the new PDK elelctrohydraulic 7-speed |
| Porsche's idea for a twin clutch transmission dates back the eighties - they
introduced the system in 1983 in a 956 race car, and later won a World
Championship round at Monza in '86 with a twin clutch equipped 962 Group C
racer. Since that brief success, Porsche stuck with single clutch transmissions
in racing and road cars until now with the new seven-speed PDK transmission
replacing Tiptronic. Aside from physically having two clutches, today's PDK
transmission (Porsche-Doppelkupplung, or Porsche Double Clutch) bears no
relation to the racing transmissions of the 80's. For the past six years, Porsche |
Better Handling
 Want to make your Boxster or
Cayman feel like a racecar without
making the ride undriveably stiff?
The Porsche GT3 front swaybar,
and an aftermarket rear bar, as
used in the Spec Boxster racing
class make a tremendous difference
in cornering feel on these
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change directions more quickly,
and ultimately may produce more
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through corners. |
| has worked directly with gearbox
maker ZF onsite at their Weissach
test facility to develop the new system
and shipped test mules to California to
work out the bugs right here on the
hills of San Francisco. The sevenspeed
layout features two wet clutches
(one inside another) and two separate
transmission layouts for even,
(2,4,6) and odd, (1,3,5,7, and reverse)
gears. Seventh gear is strictly an
overdrive to boost fuel economy. The
clutches work independent of each
other, are closed by a piston and
bathed in their own fluid separate from
the gear oil for the cogs in the rear of
the box. One advantage of having two
separate shafts with odd and even
gears is that sequential gears can be
selected on both cogs, so power is
virtually uninterrupted while shifting. It
can also skip gears on downshifts for
example changing from 7th to 2nd in
a single change. The advantages of
the system are faster changes than
manual shifting, reduced fuel consumption
(roughly 12% over previous
Tiptronic), and it weighs in 22 lbs |
|
| lighter than the old Tiptronic box.
It's still 66lbs heavier than the manual
six-speed box. Porsche thinks
this new gearbox will increase the
number of semi-automatic buyers in
the US from one-third to roughly
half. To unlock the full potential of
the transmission and the complex
software that runs it, you have to
order it with the Sport-Chrono
package with sport and track settings
for unbelievably quick gear
changes, along with a launch control
strategy.
PDK Carrera in its native environment
Porsche displayed this cutaway PDK
equipped 911 Carrera for the press
launch last summer in Germany |
