DSG

[Edward R. Wendell IV]

I finally got some time to chime in on this whole DSG thing. I can't 
remember who it was but some one stated:
"But what I was expecting was a kick-in-tha-butt when upshifting."
As I recall, said quote was used as evidence of a problem with the DSG 
system. I'd like to examine the physics of why I think that that action 
is not possible due to the configuration of DSG and why it is also not 
consistent with true performance driving with a conventional manual.
	First off, a "kick-in-tha-butt" feel in an automobile can only mean a 
large increase in acceleration and therefore a large increase in torque 
at the driving axle. But where is that extra torque coming from? It's 
certainly not the engine. Even if you factor in the fact that the 
torque curve falls off at higher rpm it's not that dramatic, especially 
when you consider that by shifting to a higher gear you have radically 
reduced the torque multiplication provided by the gearbox. I contend 
that the extra torque spike is due entirely to the energy that was 
stored in the mass of the rotating flywheel. Following that line of 
thought, the flywheel would therefor have to be spinning faster than it 
should be when it is reconnected to the driveline via the clutch. So I 
guess my point is, if the rpm isn't matched properly, than you will get 
that "kick", which is impossible if the DSG is programmed correctly. 
That also leads to the conclusion that people who are bragging that 
their car has a powerful engine because they can bark the tires when 
upshifting are really bragging about how heavy their flywheel is and 
how much they can abuse their clutch, engine mounts, and drive axle 
bushings.
	Concerning the design of the DSG gearbox, with two clutches competing 
for the space that used to be occupied by one I would imagine that the 
size and therefore mass of the flywheel is quite low. As one of the 
factors that weighs in favor of a heavy flywheel is drivability, ie 
resistance to stalling and smoother throttle response when shifting, 
than the throttle by wire and fancy shifting and clutching algorithms 
in the DSG controller would eliminate that need.
	So I guess that my point is that DSG won't feel like a conventional 
manual when shifted, especially when one is used to said conventional 
manual being used somewhat incorrectly. I personally pride myself on 
getting a shift so right that a person in the passenger seat with a 
blindfold would be hard pressed to tell that a shift had taken place. 
It sounds to me like the DSG is programmed to do the same.

Roy Wendell
Clarksburg WV USA
86, 87 5kcstq
87 MR2 times 2
Three turbos, two quattros, too much fun