So when Vin Diesel talks about double clutching when drag racing in Fast and the Furious he doesn't know what the hell hes talking about since it's more a road course manuever...
Why in God's name would you want to double-clutch these days?
In the days of non-sychronized transmissions, you double-clutched to syc your engine speed with the gear so you wouldn't grind the gears. I believe that there are still some trucks that don't have synchronized transmissions, because you can still hear some big rigs, dump trucks and the like double-clutching. It could just be a habit from a long time ago with older truck drivers, also.
I am not familiar with pure racing transmissions. Maybe some still need to be double clutched, but you don't hear it on any of the televised races, as far as I can tell. I would just see it as a waste of time, so I don't see why. Somebody who knows racing transmissions could elaborate.
Save your throw out bearing. Double-clutching is a waste of time.
You broke a forum rule... search for topics before posting a duplicate question. This has been covered many times.... anyway, here is my thoughts...
If you don't know what this is, do some reading of how transmissions work and how the different "shafts" (input, output, intermediate) work together when the trans is in gear and the clutch is in and out. Howstuffworks is a great website IMHO: http://auto.howstuffworks.com/transmission6.htm
Double clutching is a waste of time and gains you virtually nothing with the modern transmissions used today. I'm guessing your familiar with the process. All it does mecanically is spin the intermediate shaft up to speed so your syncro's don't have to. It's a waste of time.