Just about every form of racing involves some sort of manipulation of a transmission. The transimission is simply a set of gears that turns the rotation of your engine into the rotation of your drive wheels. Every car has a transmission, as without a transmission you are just revving an engine that isn’t attached to anything.

Why Do We Need Multiple Gears?
This is an important question. In short, there is a set range of rpms that your car’s engine will operate in. Usually this would be an idle of just under 1000rpm to around 6000-7000rpm (though different engines have different redlines). Additionally, every engine will produce the most power, torque, and efficiency in a smaller segment of its rev range. I.e., for my Miata, I get all of my power starting around 4500 rpm and going up to the redline of 7000rpm.

Different gears allow the engine be able to operate in its optimum rev range at a wide variety of speeds. Think of how a bicycle works, and you should see that the same applies to cars and car engines. The engine on a bicycle (your legs) can only turn at a relatively small range of rotations (your pedal strokes/minute). If you only had 1 gear, you wouldn’t be able to ride your bike very well. You would either have no power at low speeds, in exchange for a faster top speed, or lots of power at low speed by no ability to go fast as your legs couldn’t move fast enough. Having multiple gears (over 20 in modern bikes) lets you keep you legs moving at their optimum rate over a larger range of speeds. The same holds true for cars, but can be accomplished with only 5 or 6 gears.

What is a Clutch and Why Do We Need it?
A clutch is simply a means to disengage the engine from the drive wheels. It is needed because a gasoline engine cannot go down to 0 rpm without stalling. As such, you need a way to introduce slip in the drivetrain so that when you’re wheels are at 0 rpm (stopped at a light, for instance), you can gradually bring them up to the same speed as the engine.

Why Bother with a Manual Transmission?
This also is an important question. For most people driving to and from work, they don’t care what gear their car is in as long as the car moves like it is supposed to. This mentality does not work when trying to extract maximum performance from a car. As a driver, you want to use the gear that puts the engine in its optimum rev range for any particular corner or situation. Automatics can do this to a degree, but they do not have the foresight to downshift before a corner and hold that gear throughout the corner.

Holding a gear in a corner is very important on the track because it lets you be smooth in your throttle application. Think of what happens when you get on the throttle in a corner - you want to slowly and smoothly apply power to gradually shift the weight onto the rear tires. If you give too much gas too suddenly, the car can spin. Now imagine what happens with an automatic transmission: you go into a corner, slowly give the car more gas, then the transmission realizes it needs to down shift. Now the tranny downshifts violently, the car lurches, and all of that smoothness you are trying to extract goes right out the window. Worst case scenario: you spin.

The Engagement Point and How to Make Your Car Move
Thats all well and good, you say, but I just want to make my car move. So, here is how you do it: press the clutch pedal IN, which disengages the engine from the drivetrain. Now you can select whichever gear you want using the shifter. Put the shifter into 1st gear. Now slowly begin releasing the clutch pedal. At a certain point, called the engagment point, the clutch disc will begin to touch the flywheel of the engine. When it does, power will be transferred to your wheels and the car will begin to move forward. Make sure you hold the clutch at the engagement point for a few seconds to get the car slowly and smoothly up to speed, otherwise you will either stall the car or screech your tires as you accelerate the wheels instantaneously up to speed.

In its simplest form, think of 2 spinning discs touching each other. The flywheel is connected to the engine, and the clutch to the rest of the drivetrain. As you push in the clutch pedal, the clutch disc moves away from the flywheel, allowing slip into the drivetrain. This point is crucial to being smooth - without holding the clutch pedal at the engagement point for a little bit, you are just slamming the 2 discs together. If they aren’t moving at exactly the same speed, there will be much lurking and bucking as the engine and drivetrain are instantly snapped to the correct speed.