Quote:
Originally Posted by javadog
You are trying to match the speeds of some of the parts in the gear clusters on the input and output shaft of the transmission. In a broader sense, on a downshift, you are raising the engine speed to the level it will be when the next lower gear has been engaged. On an upshift, this isn't necessary, as the parts in question are naturally wanting to slow down anyway when the clutch disengages.
JR
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Partially exact. Double clutching is the only way to also bring the
gear-to-select assembly up to the same speed as the engine to match the rotational speed of the output shaft (differential/drive axles). And that is most needed for downshifting to reduce wear on the synchros.
I couldn't find a suitable video demo on YouTube. The double-clutch demo videos with race cars were performed at race speeds and thus difficult to follow. Slo-mo would have been better. The other videos don't provide a clear view of the shift lever position during the double clutch maneuver nor the sound of the engine when the throttle is blipped momentarily.
Sherwood