how to do it?
what's the good?
why?
when?

 

U mean heal/toe shifting?? rev matching??
Do a search on heel/toe shifting..

 

double clutching is:

press the clutch, put it in neutral, let go of the clutch, match the revs, press the clutch, put it in the lower gear, let go of the clutch.

You can do this in one fast motion if you practice. The reason you do this is to get the speed of the "layshaft" to the speed....

 

See this https://www.s2ki.com/forums/showthread.php?...?threadid=15793 for good discussion. Search on Double clutch for other threads about same.

 

Here's all you need to know: Don't bother.

 

I don't double clutch but I do routinely rev match. Double clutching was more important when trannies had bad or no syncros at all and for me, is a bit time consuming. When I downshift, I simply "blip" the throttle just prior to clutch re-engagement. (the amount of throttle blip depends on the engine speed at the time of downshift and this can be learned by experience). Proper rev matching smooths out the transition to the lower gear so you don't "lurch" when the clutch comes back out, allowing more engine braking and lessoning wear and tear on the clutch. (Some people don't worry about this because brake parts are cheaper than clutch and engine parts.) And it sounds cool. Heal and toe is not such an important issue on the street. If you want to race then it might be something you should learn to do.

 

thank you very much every one...

 

Sev properly described the operation. It can be used for either upshifting or downshifting.

 

As brief as i made the description, i believe it's clear....

I only double clutch when downshifting to 1st, all the other gears i just rev match. The reason is the big ratio difference between 2nd and 1st....