Can someone explain the concept of
" Double clutching ".

I hear this term often at the races..
but not sure what it actually is..

Thanks

 

Double clutching is used when downshifting and works like this:

1. Clutch in
2. Shift into neutral
3. Clutch out
4. Rev engine
5. Clutch in
6. Shift into lower gear

Modern synchros have lessened the need for double clutching, especially when only shifting down one gear. However, I like the way the tranny shifts when I double clutch so I usually do it. You pretty much need it when shifting down 2 gears. You'll also need it whenever you shift into 1st gear while rolling since 1st doesn't have a synchro. The procedure is from the days when gearboxes either had no synchros or had sucky synchros. The idea is you are revving the car in neutral to speed up the layshaft so its at the same speed as the gear you want. Here is a good diagram of a gearbox:

http://www.howstuffworks.com/transmission3.htm

Basically in neutral, the layshaft is attached to the engine and the gears are attached to the wheels, but the layshaft and gears are not attached to each other. When you shift into gear, they mesh together. If their speeds are different, the synchros help to smooth the transistion, but its better if they're just the same to start with. The reason you have to let out the clutch and rev instead of just revving with the clutch in is that the layshaft is not attached to the engine with the clutch out, so it won't change its speed with the clutch in. Hope that helps...

 

http://www.howstuffworks.com/transmission.htm

 

The technique generally works best with a little heel and toe action to boot .. helps settle the car nicely while you prepare for the corner, keeps the weight distribution over the front wheels while you're braking .. that way you can brake harder while maintaining traction.

1. Start Braking
2. Clutch in
3. Shift into neutral
4. Clutch out
5. Rev engine while keeping steady pressure on the brake .. Clutch in at the same time
6. Shift into lower gear
7. Clutch out
8. Ease off brake
9. Turn into apex of corner

 

WHAT THE ******* HELL! Double clutching is only useful for dogboxes.