Can anyone tell me what a double clutch is, and how is benificial for racing? I over heard a couple of guys talking about it and I don't have a clue. Thanks for your info.

 

Double clutch is as follows:
Clutch all the way in
Take car out of gear (say out of first)
Clutch all the way out
Clutch all the way in
Put car into second
Clutch all the way out

Used to have to do that all the time in the days before synchros (still do in most big rigs). As far as being beneficial for racing,

 

The point of double clutching is to match engine rpm with transmission input shaft rpm. Since the speed of the gearing is controlled by vehicle speed and the engine rpm by the throttle they out of synch when you change gears. Newer racing trannys have made it almost obsolete, but stock trannys need the protection when used for racing. It's really not necessary when upshifting, but downshifting it helps keep the car under control when entering or in a corner and makes the syncros last longer. Obviously it takes longer to shift so newer racing trannys are built differently.