Recently received this message from a Porsche representative.

"Unfortunately, it is not possible to retrofit the rev-matching technology
to an already existing 991 C2 model.
This would require the change of the whole transmission unit as there are
additional sensors integrated in the transmission box."

Fred S.

 

Looks like it's right in between the manual and the PDK. Maybe the best of both? Hey, what if it's really a modified PDK and the clutch pedal isn't really connected to anything (or is a fly-by-wire clutch pedal). Just saying.....

 

Sounds like 'rev-matching' is a better term. I doubt it is truly doing a double-declutch like in the days of yore before synchros. (i.e. clutch in, shift to neutral, clutch out, clutch in, shift to next gear, blip throttle, clutch out)

So, basically they are making a PDK with a superfluous clutch pedal?

 

I thought that the 7 speed is basically a PDK unit with a clutch... no?

 

If it's a true manual, then it should be quite different from the PDK -- eg mechanically simpler, only one clutch, etc. I was jus joking that they might get to the point where the manual version is really just a PDK with a somewhat superfluous third pedal.

 

Here ya go guys.

 

Sid:
You are amazing in that you consistently come up with such great new and technical images!

ChuckJ

 

If I understand correctly - Automatic Double Declutching works like this


Double de-clutching is used in shifting non-synchronized manual transmissions, where the driver must adjust the speed of the input shaft to match the speed of the output shaft by modulating engine RPM with throttle; obtaining the RPM in which the engine would be turning based on your traveling speed in the gear you want to select (i.e you are traveling 80 MPH in 4th at 4000 RPM for example and want to drop to 3nd, your input shaft speed would need to be increased to 6000 RPM in order to make the gear change (I just made up rough numbers for this, but similar to the Getrag420G in a BMW 46M). To do this, the transmission must be in Neutral with the clutch disengaged (clutch pedal out). Once the desired input shaft speed is reached, quickly engage the clutch and select the gear, release the clutch and off you go.


That is essentially what double clutching is for those that don't know - Clutch in, shift to neutral, clutch out, rev match, clutch in, select gear, clutch out. With practice, you can skip the clutch in on the shift to neutral by applying slight pressure to the stick and remove drivetrain load with throttle and the box will slide right into neutral. Even more skilled drivers can skip the clutch completely if they can match perfectly, although I don't recommend this unless you are Warren Buffet or driving an Eaton Fuller 8LL.


What I think Porsche is doing with the auto double de-clutching is eliminating the need for the driver to depress and release the clutch twice on shifting. Most likely it is using a servo to operate the clutch, and once the driver depresses the clutch manually to make the shift the driver holds the clutch in throughout the shift however the servo actually releases the clutch automatically, even though the driver still has it depressed, when the transmission is going through neutral, RPM is then adjusted to match input shaft speed for the selected speed, and the servo then releases the clutch after that is accomplished, then the next gear is selected, the driver releases the clutch as usual and you're on your way.


So essentially, the transmission "automatically" performs the intermediary clutch actions while the driver still engages and disengages the clutch as they would normally during a gear change in a synchronized transmission.