Originally Posted by dak911

So City/Urban used vehicles vs Suburban used vehicles will have a shorter transmission life?

Originally Posted by Petza914

I would say so, and the real irony is one reason people select the PDK over a manual is because they sit in traffic.

Originally Posted by VAGfan

I was monitoring the real-time clutch pressures, during some stop-and-go driving. I did not monitor the fluid temp, but I think the temperatures will start climbing if you are stuck in traffic, spending long periods in D, without the car not moving.
No, the engineers are not idiots, but making the dual-clutch smooth (by keeping the clutch slightly engaged, and slipping) before the driver releases the brake and starts accelerating is a goal of the transmission control software, to prevent customer complaints of "clunky" or "jerky" transmission behavior, as most people are used-to the smoother operation (and low speed creep behavior) of conventional automatic transmissions. The clutches are durable enough for some calculated average lifetime of clutch slip during stop-and-go traffic usage, but knowing how this transmission works allows us to shift to N, during long periods of stand-stills, to hopefully extend the life of the transmission.

Clutch slipping is the only thing that raises fluid temperatures. Changing gears doesn't create significant friction to increase the fluid temperature.

Originally Posted by VAGfan

The point is that the slight clutch engagement is done on-purpose to mimic torque converter creep.

Originally Posted by Larson E. Rapp

Fact is, I have yet to hear of anyone needing to replace those clutches. So whatever they're doing, it seems to be OK.

I'm skeptical that slipping them at idle will generate a ton of heat, but could be persuaded by data. Admittedly, I also don't see why it 's necessary to slip the clutches constantly in order to achieve smooth takeoffs, unless it's important to keep the discs warm for whatever reason.

Originally Posted by DHL

So why the suggestion to use sport mode full time if the clutch slippage also occurs in that mode? Is it because sport mode lowers coolant temps (slightly)? BTW I am a new owner of a 2022 GTS and this post has me concerned. Luckily I purchased the extended Porsche warranty for up to 10 years and am now glad I did.

Also, if you are right, maybe the first reason I have heard to re-engage that annoying "Start-Stop" function wicj shuts down the drive train while stationary.

Originally Posted by chassis

What informs the skepticism?

Originally Posted by chassis

Sport mode uses faster gear changes, which means less clutch slippage per gear change. Consider the 3-speed Chrysler Torqueflite and Ford C-4 transmissions, which took an eternity to shift gears. Time between gears is proportional to clutch slip. More time between gears = more clutch slip = more comfortable gear change.

Less clutch slip = longer clutch life = possibly less comfortable gear change. Sport mode = less clutch slip = longer clutch life.

Originally Posted by chassis

Sport mode uses faster gear changes, which means less clutch slippage per gear change. Consider the 3-speed Chrysler Torqueflite and Ford C-4 transmissions, which took an eternity to shift gears. Time between gears is proportional to clutch slip. More time between gears = more clutch slip = more comfortable gear change.

Less clutch slip = longer clutch life = possibly less comfortable gear change. Sport mode = less clutch slip = longer clutch life.

Originally Posted by ilovemaui

are you sure sport mode uses faster gear changes? It seems to me it holds longer.

Originally Posted by Larson E. Rapp

Experience driving a stick shift. I don't have to slip the clutch while I'm waiting at a red light, so why does the PDK need to?

It is known that the PDK maintains calibrated "bite point" measurements for clutch engagement, which is more than I do. It knows how to engage the clutch in first gear quickly and smoothly.

Originally Posted by DHL

Yes, but I thought the point was heat generation, the majority of it being produced by slippage at idle, not during normal high RPM gear changes (since these occur over a much shorter time period).

And I agree regarding drivability. I had an X3 M40i that literally slammed gear changes in Sport+ mode to such an extent it unsettled the chassis and sounded like explosions at every gear change. Quite uncomfortable to drive and one of the reasons I have a Macan GTS instead.

Originally Posted by chassis

The point made earlier in the thread is that clutch slip generates heat. This is correct. And clutch slip is needed at launch for smooth and comfortable drivability. I see that we are in agreement here.