> > All right, class, pay attention. Let's say you are driving up hill and find that the gear you are in is too high and you are losing speed. To get into a lower gear smoothly, you push in the clutch and shift to neutral. You let the clutch back out and then you blip the gas a little to speed up the engine. With the clutch engaged, this also speeds up the gears in the transmission.
> > Then you push the clutch pedal back in, shift into the lower gear and get back on the gas. If you do it quickly and smoothly and bring the engine speed up just enough, the gears don't make a sound.
> > Actually, it takes a little practice, but it's not difficult and even if you miss it a little, you really just get some noise. Gears are tough.
> > I used to shift into low gear while moving just to impress my buddies. In those days, first gear wasn't syncronized. And they were really impressed because none of my buddies was the brightest bulb on the Christmas tree. You can make it sound like a double clutch if you just leave the clutch in the whole time, but it won't work unless the transmission is fully syncronized.
> > Howard
>
> What is the benefit of this? Why don't you just downshift? I just push the clutch in, shift from 4th to 3rd, release the clutch and go. Have I been doing this wrong for the past umpteen years?
>
> -Faux "what's that grinding noise?" Pas

If it works, don't fix it. Double clutching is usually not necessary with a modern transmission. But old transmissions often were not synchronized, especially on trucks. Up until about 1960 or so, most cars had an unsynchronized first gear and you couldn't shift into it without risking damage if the car was moving. Even modern cars will downshift a little easier if you double clutch, but the difference is not worth the trouble to most drivers. Listen to trailer trucks going uphill. Sometimes you can hear them double-clutching. Those guys are pros.
Howard