Navigate this Site:Home
Driving a Stick
Treo 650 Software
Dr. Fun Archive
How to drive a car with a manual (standard) transmission, PROPERLY
Feel free to copy this article as long as above credit and hyperlink to http://www.nerocam.com is left intact
It's really kind of alarming how many people think they know the correct way to drive a car with a manual transmission, but don't. I have driven in cars with many people who are convinced they are "great drivers", where I am wincing during every shift.
So this is my short tutorial. I don't profess to be an expert driver, I know many people who can drive better than I can. There may be errors in what I have written here. However, I do know the internal workings of a manual transmission, and what one should and should not do to it while driving.
Unfortunately, the first thing you need to know in order to drive a manual car, is how the transmission works.
How a manual transmission works
This is a very simplified explanation of what happens inside a manual transmission. First off, why do we need a transmission in the first place? The reason for the existence of the transmission is due to two failings in the gasoline (or diesel) engine:
In contrast, an electric motor generates maximum torque when it is stopped, and its torque decreases as RPM increases; exactly the opposite to a gasoline engine. As well, the efficiency of an electric motor is essentially maintained regardless of RPM. This is why electric-driven vehicles (such as golf carts) usually do not have transmissions - they don't need them.
Because there is a limited speed range in which a gasoline engine produces usable power, and that this speed range itself is limited mechanically, we need to use some gears, namely the transmission, to match the speed of the car to the speed of the engine as we accelerate - otherwise the car's overall top speed would limited to the top speed of the engine.
Consider this picture:
If the engine is connected to the gear on the left, and the wheels are connected to the gear on the right, the wheels will be turning much slower than the engine. This would be a good representation of a low gear, say first gear.
Next, consider this picture:
If the engine is connected to the gear on the left, and the wheels are connected to the gear on the right, the wheels will be turning much faster than the engine. The ratio of the gears has increased. This would be a good representation of a high gear, say fourth gear.
So a transmission is essentially a box of different gears, each with a different ratio to one another, that allows the wheels of the car to turn at a different speed than the engine, depending on what gear you have it in.
Sounds quite simple, and it is. However, now things get a bit tricky. How do we disengage from one gear and engage to another? The design of the gears inside the transmission are such that if there is any torque being delivered to the wheels (acceleration) or from the wheels to the engine (deceleration), the gears are locked together quite tightly. If you are accelerating your car, it is virtually impossible to pull it out of gear without a lot of force. You could try to adjust your throttle (gas pedal) just right so that the engine is not delivering or accepting torque to or from the wheels, then pull the transmission out of gear - and it is possible (although not recommended) to do just this. If you then wanted to shift it into another gear, you could once again adjust your throttle until the speed of the engine matched the speed of the new gear ratio, and gently push it into gear. Again, it is possible (and again not recommended) to do this. If you have a car whose clutch has failed, this is the only way you can shift gears.
Clearly, we need a way to disconnect the engine from the wheels momentarily, so that we can shift gears easily. The device that accomplishes this is called the clutch, and it is connected directly to your clutch pedal.
The clutch is essentially two round pieces that touch each other: the clutch plate and the clutch lining. The plate is a piece of metal, and the lining is made up of material very similar to your brake pads. The clutch plate is connected to the engine, and the lining is connected to the transmission. When you press the clutch pedal down, these two pieces are pulled apart, so that the transmission (and hence the wheels of the car) is no longer connected to the engine. When you let the clutch pedal up, the two pieces are pushed together with considerable force, so that the transmission is once again connected to (and receiving power from) the engine. Because this will not be an instantaneous connection (i.e. there will be a bit of slippage until the clutch is fully engaged), we have the clutch lining, made out of a material similar to brake pads. Over time, and depending on the skill of the driver, this lining will wear down, to the point that there is no longer enough lining left to make sufficient contact against the clutch plate. At this point, the clutch will slip even when it is fully engaged, and the clutch lining will need to be replaced.
So now we have a way to disconnect the transmission from the engine so that we can shift from one gear to another. However, we still have another problem. Let's look at the sequence of events that occurs when we shift, say from third to second gear:
This sounds quite simple, but we do have a problem: In the third step described above, the input portion of the transmission is connected to the output portion. However, the two gears that are connecting to one another are spinning at very different speeds - and the input gear is slowing down! So how do the two gears mesh together smoothly?
In old cars, they didn't. You either rammed them together, "grinding" the gears until pure friction started to speed up the input gear, grinding bits of metal off in the process, or you used a technique called "double clutching". Double clutching adds one more step to the process described above:
Needless to say, this took some practice and skill. Some large trucks and buses still require this technique when shifting gears. However, engineers wanted to make life easier for car drivers, and came up with a new invention: syncromesh.
Syncromesh sounds like it might be complicated, but it's really quite simple. It is an extra piece of smooth metal between the input and output portion of the transmission. When you begin to engage one of the gears, the syncromesh touches first, and gently begins to spin the input portion of the transmission faster or slower, so that it matches the speed of the output portion. Once the speed of the input portion matches the output portion, you feel a bit of "give" in the shifter knob, and it easily glides into gear, without grinding. If you "ram" the shifter knob into place, it forces it past the syncromesh before it has a chance to fully spin the input portion of the transmission up or down, and you end up grinding the gears. This allows easy shifting up and down without having to double-clutch. Because there is slippage when you engage the syncromesh, it can wear out, just like a clutch lining. If a transmission has poorly-designed gear ratios that are too widely spaced (the difference in speed between one gear and the next is too much), the syncromesh will wear out more quickly. A worn syncromesh will often cause grinding gears, because it does not have enough surface to full spin the input portion of the transmission up or down.
Syncromesh works harder when downshifting (shifting from a higher gear to a lower gear) than when upshifting. The reason for this is that during upshifting, the syncromesh has to slow down the input portion of the transmission. However, natural friction has already started this slowing process, so it has less work to do. When downshifting, the syncromesh not only has to reverse the natural slowing process, it has to reverse it, and spin it faster than it was when the clutch was depressed.
There is usually no syncromesh in the reverse gear, which is why the car normally needs to be stopped to be able to shift into reverse - the input portion of the transmission needs to be stopped, just like the output portion before it will engage.
So now we have a basic understanding of how a transmission works. Understand that this is an extremely simplified explanation, and that there are complexities involved that have not been touched upon. For the understanding of the operation of the transmission however, this is sufficient.
Without a doubt, probably the most common mistake made in driving standard cars today is the failure to match engine speeds. It is taught incorrectly, and most people don't even know that they are doing anything wrong. Let's look at what someone does when they downshift from third to second gear:
In doing so, you have just worn your clutch a little bit more. Eventually, you will need a new clutch. If you have ever had to have a clutch replaced in a car, then you are driving your car incorrectly. If a car is driven properly, you will never have to replace the clutch for the life of the car. What is happening? Let's look at it in a little more detail:
The same thing can happen if while upshifting, too much time is taken during the shift, particularly if you are shifting between low gears (2nd and 3rd, for instance). During the time the shift is taking, the engine speed slows down, well away from what it was while the transmission was linked to it. When the shift is completed and the clutch is re-engaged, once again the clutch lining is worn away as the clutch takes the brunt of spinning the engine up to speed again.
To try to get around this upshifting problem, auto engineers added what is called a "dashpot" to the throttle system. This causes the engine to not slow down so quickly when the throttle is released - essentially, if you take your foot off of the gas pedal quickly, it causes the engine to think you are taking your foot off much slower. If you are in neutral and rev the engine to 3000 rpm, then suddenly take your foot off the gas pedal, you will notice it takes a second or two to return to idle. This is the work of the dashpot. However, this does not help us at all when downshifting.
How do we get around this downshifting problem, so that we will never have to have our clutch replaced? It takes a bit of practice. When downshifting, as you push the clutch in, give the gas pedal a little blip (quick press) - just enough to bump the RPM up to what it will be when you shift down to the next gear. As you do this, shift smoothly, then quickly release the clutch. What happens when we do this?
Sounds quite simple, but in fact it takes a great deal of practice in order to know just how much to "blip" the gas pedal in order to match the engine speed correctly. Do it too much and you are wearing the clutch. Do it not enough and you are wearing the clutch. How do you know if you're doing it right? You should not feel a surge or a sudden deceleration when the clutch is engaged. In fact, if not for the fact that you could not hear the engine, you should not be able to even know that you have shifted gears at all. Smoothness is the name of the game - the more smooth the shifting, acceleration and deceleration seems to be, the better it is for your clutch and your drivetrain. The driver is not the best judge of the level of smoothness, because he or she is expecting the shift. Ask a passenger. See if they notice any surges of acceleration or deceleration. It takes a great deal of practice to do it smoothly, and every car is a bit different.
Some people talk about "heel and toe shifting". This type of shifting is usually associated with downshifting. It is done exactly as described above, however the driver is also braking during the entire shift process. This is done by placing part of the right foot on the brake, and part of the right foot on the gas pedal. When the shift occurs, the driver "blips" the gas pedal without removing or changing the amount of pressure on the brake pedal. There is no normal reason for an everyday driver to use this kind of shifting - it is normally reserved for racing drivers, where, while coming into a corner, they want to brake as late and as hard as possible, and may need to downshift at the same time, but don't want to stop braking while downshifting. The pedals in racing cars are normally set up for this type of shifting, unlike normal road cars.
Another mistake people make while driving is to "knock it out of gear" and let the car coast, then shifting it back into gear while still moving. The problem with this is that while the car is coasting, the input portion of the transmission either stops entirely (if the clutch is depressed) or slows to idle speed (if the clutch is not depressed). When the driver attempts to shift back into gear, the syncromesh takes a beating while trying to spin the input portion of the transmission from a dead stop or near stop up to the speed the car is currently traveling down the road. This is an excellent way to quickly wear out the syncromesh in your transmission, which is not a cheap thing to repair. If you must "knock it out of gear" and coast, then before shifting it back into gear, let the clutch out, give the gas pedal a blip to spin the input portion of the transmission up to speed, push the clutch in, and then shift into gear.
A very common mistake people make is when coming to a stop at a red light, to push the clutch in, shift the car into first gear, and sit waiting with the clutch depressed. The clutch plate and clutch lining are under an enormous amount of pressure holding them together, so that they don't slip, even under tremendous acceleration. When you push the clutch pedal in, they are pulled apart, using a special bearing. When you sit at idle and in gear with the clutch depressed, it is wearing this bearing, which is under tremendous pressure. Eventually it will wear to the point of failure. When at a red light, shift to neutral and release the clutch. Shift to first gear only when you are about to move again.
The best way to learn how to drive a manual transmission? Knowledge and practice. If you've read this article, you now have the knowledge. Now go out and practice.
The best way to know how you're doing? Your passengers. Next time you're out driving with a passenger, look at them while you upshift or downshift. Is their head bobbing around? Are they uncomfortable? Think smoothness. Your goal should be to have the passenger not know that you are shifting (or braking, for that matter) at all, apart from the sounds. Look ahead. Plan ahead. If your passenger was blindfolded with earplugs, and they didn't know that you were shifting, braking or accelerating, you have achieved your goal.