Double Clutching

Hello again!

Today, I figured I'd talk a bit about a technique I've been teaching myself with manual transmissions.  This technique is called Double Clutching, or Double Declutching.  I had gotten in the hang of driving stick and I know how to shift in a quick and smooth manner, however my dad told me about double clutching and the people who race use this.  He also explained the basic principles and its purpose to me.

Starting from one gear (while in motion), you press the clutch, place the shifter into neutral and release the clutch.  This first part is the same for both downshifting and upshifting.  To upshift, you DON'T hit the gas because you are allowing the engine to lower the RPM. Then you press the clutch and put it into a higher gear.  I haven't been doing double clutching for too long, so I don't know if this is any more effective than simply naturally shifting up.  However to downshift, you have to tap the gas to increase the RPM so that the engine can match the lower gear.  Then, you quickly press the clutch and put the shifter into the lower gear and release the clutch.  Upon accelerating, you should notice that the transition is smoother than not double clutching.  I find that when I normally downshift, there's a bit of a jerk.

However, you don't want to do this if you are downshifting to use engine-braking.  Engine braking is when the engine is underpowered and the energy from the car's motion is used to speed up the engine, (Newton's laws at work).  So when you don't double clutch, and you feel the jerk upon downshifting, it's the engine slowing the car down slightly.  This is a very useful tool that you can use to more quickly brake and lengthen the lifespan of the brake pads by not placing as much force on the brakes.

Just be careful when you're practicing these techniques.  You can start slowly to get the hang of these things, like double-clutching, even if it's not effective.  Getting a hang for the motions can prevent you from crashing your gears. Have fun!


On an unrelated note, I saw a McLaren MP4-12C today.  The McLaren isn't a brand seen often on the road mostly because they don't have many cars on the market and came to the public fairly recently. McLaren is a big name in Formula One racing as they are partnered up with Mercedes-Benz and their racer, Jenson Button is one of the top racers in the world.  The precursor to the MP4-12C, the McLaren F1, was McLaren's first car to their name and was the fastest car in the world when it came out (1992).  And with a top speed of 231 mph, it's still one of the fastest cars in the world.

McLaren MP4-12C (source: Wikipedia)