neil.schneider

Hi guys,
I am looking for an opinion regarding the way our PDK shifts. I feel the transmission shifts far faster in a downshift than upshifts. Any opinions?

Happy911S

I never noticed this. I will pay closer attention now to see if I can detect it.

CSK 911 C4S

Any particular mode?

I find in eco mode the car loves 7th gear and it hates to downshift to 6th without a little encouragement from the go pedal. Sport mode is pretty quick .... up and down.... love when it downshifts with the burble.

Archimedes

When my car is cold and/or I'm driving leisurely, the upshifts feel a little slower than the downshifts. However, when I'm driving the car hard, running it into the upper rev range, the upshifts seem much quicker. I'm assuming the transmission reacts to RPM and makes a quicker upshift at high and/or rapidly increasing RPMs, but I'm not certain.

Key Left

Down shift time would be quicker as PDK is specigically designed to help avoid engine braking time as it wastes fuel and creates more emissions. Simple! ( It also reduces driver interaction and engagement.)

997s07

I don't have a PDK but my car is also pretty bad with engine braking. How does avoiding engine braking reduce emissions? The RPMs stay up for a longer period.

worf928

No sence that makes. At all. I susepct a high probability that you have never driven a PDK Porsche.

PDK-equipped Porsches have a coasting mode enabled as part of auto-stop/start that disengages the clutches during overrun. The result is no engine braking.

However, with auto-stop/start disabled (default for 95% of the folks on this board, it would seem) triggering a down shift with the PDK results in a rev-matched downshift that does result in engine braking.

worf928

What does that mean? "Bad with engine braking." I cannot extract any meaning from that phrase.


I have no idea. Porsche claims that it does. Here's a counter-argument:

http://www.popularmechanics.com/cars...-fuel-economy/

Intuitively, engine braking should result in less fuel use over coasting since in overrun (engine braking) fuel is cut off and result in lower emissions since no fuel is burned to keep the engine idling.

However, with coasting mode as part of auto-start/stop it is logical to assume that the engine might be turned off during coasting.

Jay-S

My subjective opinion with PDK is up shifts are slower than down shifts.

I also saw a YouTube video a while back where a professional race driver said the same thing with respect to the 911 PDK.