So, I’m going to be buying a manual transmission car in the next couple weeks, and I have a question about double-clutching.
As I understand it, if you’re downshifting from a higher gear (to accelerate quickly/pass someone/whatever), it’s easier on the synchros in the transmission if you double-clutch instead of shifting normally. The idea is to get the engine RPMs to match the speed of the wheels before shifting, so the synchros don’t have to bother.
The process as I understand it is as follows:
- Clutch in, shift into neutral, clutch out.
- Rev the engine to where it needs to be for the speed you’re going and the gear you’re shifting into.
- Clutch in, shift into the lower gear, clutch out.
What I don’t understand is why you need to take the clutch out before revving the engine. And also, why you can’t simply rev the engine after you’ve shifted into the lower gear but before you’ve let the clutch out?