Originally Posted by
RITmusic2k
I'm absolutely in agreement with you, Derek. It's a scenario that generates repeatable results highlighting the difference between CDV and no CDV.
When I first got my car, I tried dropping two gears and stomping on it to see how quickly the car could get out of the way. Coming from a car where pedal position corresponded exactly to clutch disc position, I got hard on the gas as soon as my foot was off the clutch pedal, and the engine revs surged and settled like a failing clutch would, because, well... the clutch was slipping exactly the same way due to that restricted flow.
Actually, the above is a little simplified... the truth is that the clutch disc makes contact with the flywheel much sooner than the perceived "engagement point"... what we typically think of as clutch disc travel is actually more like "clutch disc travel" over the first 30% of clutch pedal travel followed by "progressively increasing clamping force" over the remaining 70% of clutch pedal travel; the engagement point we feel is somewhere in that 70% range where you hit a threshold of sufficient clamping force to hold the clutch disc and flywheel together without slippage.
That threshold amount of force rises slightly with increasing disparity between the rotational speeds of the clutch disc and flywheel (e.g., when revs are poorly matched), but for the most part it's in the same place. More accurately, the relatively-fixed amount of clamping force required to engage the clutch corresponds with a relatively-fixed position in the clutch pedal's travel. Or it should, if there's no flow restriction.
As quickly as you can get to that position, and thus that amount of clamping force, is how quickly you can get on the throttle after a shift. But the rate of application of that clamping force is what the CDV limits. So if your foot makes it to the point where that amount of clamping force is normally applied sooner than that force is actually applied, you'll get slippage until the CDV allows enough fluid through. In my experience, my foot could get there an entire second before the CDV caught up. That's enough time for some very annoying over-revving and slippage.