Double-clutching is a technique that was developed way back in the infancy of motoring, when manual transmissions had no synchromesh, and it was only driver skill that prevented turning a gearbox into a can of scrap metal.
Nowadays, double-clutching is still a useful skill to master for downshifting, as it removes almost all stress from the synchros, allowing a lower gear to be selected with the shifter gliding through the gate "like butter", with no resistance.
The cadence would be as follows for a "four-to-two" downshift:
While cruising in 4th, push the clutch in, moving the shifter to neutral....
Then, let the clutch out, and blip the throttle to raise the RPMs....
On the downrev, stab the clutch again, while moving the shifter *quickly* to 2nd gear.
If performed correctly, you will be amazed at how smoothly and effortlessly it went.
The road goes ever onward....
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