I would disagree about calling the above double clutching.
Double clutching is primarily a method used on vehicles without synchromesh (like many trucks) and is used to match (internal in the transmission) gear speeds when downshifting.
Example of double clutching during downshifting from 3rd to 2nd: You depress the clutch, shift the transmission into neutral, release the clutch, press the gas to speed up the engine (which now brings up to to speed the 'front' end of the transmission to hopefully match the back end speed), press the clutch again (the 2nd time aka double) and shift into 2nd. Release clutch.
If done properly, this minimizes the speed difference between the transmission gears attached to the engine (via the clutch) and the ones attached to the drive shaft thus no grinding.
The use of double clutching is required more on the downshift due to the fact that this is the time that the front end of the transmissions needs to be 'speed up' for the match. Up shifting is more an issue of timing (waiting for the transmission front-end speed to come down) thus double clutching is not required unless you are in a hurry.
But it would be a catch 22 in our cars. Synchromesh is provided to avoid the need for double clutching. By double clutching on a transmission with syncro you would be 'saving' the syncro rings but at the expense of our precious clutch material (not to mention the extra work etc).
eric_lee said:
I blip the throttle before I engage the lower gear (not really heel and toeing here) and if I up shift I do the same.
Does this work?
Bliping the throttle before releasing the clutch to engage the lower gear is the correct way to match the engine speed to the transmissions front end speed (after the gear is changed and syncro have done their job). Bliping on the upshift is unneccesary at best and bad if done incorrectly ie if you don't wait for the engine speed to come back down before engaging the clutch.
From my angle the issue about clutch wearing still comes back to a simple test and that is to notice how much the engine revs change as you engage the clutch. If the engine revs change during engaging then you are causing unnecessary wear to the clutch material.
-mick