Quote:
Originally Posted by aznatama
I can double-clutch a near perfect smooth downshift without even feathering the clutch upon let out. In NO WAY WHATSOEVER is this slower than merely waiting for the synchros. Synchros bridge small speed gaps, not large ones, and are thus much better for upshifting (not having to wait for rev to drop), and not as well for downshifting. Double-clutch downshifting forces the engine side of the gears to speed up to match (or nearly match) the faster spinning lower gears as opposed to waiting for the faster spinning lower gears to slow down (via braking) to match the slower spinning engine-side gears.
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I have always wondered what happens during a double clutch, so lets work through it.
Lets say you are at 3000 RPM in 4th to downshift to 3rd you:
A- Depress the clutch: this decouples the engine from the trans
move gear from 4th to neutral: slider ring decoupled final drive from input shaft.
The input shaft is now spinning down under friction (was just at 3000 RPM input).
B- While shifting out of gear you started to bring the engine revs UP in anticipation of the shift.
C- You release the clutch: this recouples the engine to the trans input shaft so you are bringing the shaft up to whatever speed the engine is at
you continue to raise the engine (and input shaft up in RPM) while in neutral.
D- Now you depress the clutch again decoupling the engine & input shaft.
E- Now you move the slider into 3rd gear where the synchros guarantee input shaft at ~4000 RPM before engagement.
F- Now you release the clutch and are in 3rd at 4000 RPM
I just have a hard time believing, that a human can negotiate all of the above in the split second that I can perform a "regular" downshift.
In fact I think I can demonstrate a downshift with no clutch about the same speed as a double clutch.
I have a theory that people who are really in tune with their car do not even disengage the clutch all the way during every shift, but dont even realize it until the rare time where you grind and wonder "what was up with that...."
I get the theory behind the double clutch, but I guess I'll have to try it some before I believe it.