- So I recently went to the birthday party of a friend of mine. While there, I met some interesting people and added them on Facebook afterwards. You know, like you do.
- Today, though, I found out that one of the people I added didn't know the difference between the types of drivetrain layouts in cars.
- *DUN DUN DUUUUUUN*
- Okay well, maybe thats a bit to dramatic. After all, for most people, it really doesn't matter. Still, it seems cars have become more of a mystical item these days, like computers, where people don't understand them maybe as well as they should.
- So, in my effort to help clear things up, in this short piece, I'll try and explain the major differences between the three types of car layouts: Front wheel drive, rear wheel drive, and four wheel drive.
- But before we go on, let me give you the TL;DL (or too long; didn't listen) version.
- It all has to do with which set of wheels spin when you hit the gas; the front or the rear. On a front wheel drive car, the front wheels spin. On a rear wheel drive car, the rear wheels spin. And, on a four wheel drive car, generally all four wheels spin.
- These three layouts each have advantages and disadvantages, and I'll be explaining them in the rest of this piece.
- Front wheel drive:
- Front wheel drive is the most common type of layout used by automobiles today. Being lighter due to less parts, the most noted advantage of front wheel drive is its fuel efficiency. And with the driving wheels up front, there is no need for a drive shaft running down the length of the car, eliminating the need for the hump found in many passenger cars (other than possibly for the exhaust system) which means more interior space for passengers and cargo.
- In addition, front wheel drive cars tend to handle more predictably, being less likely to oversteer and fishtail. Even in slippery conditions, because the car pulls in the direction you point the wheels, it's much easier for novice drivers to get themselves out of a skid. For skilled drivers, though, front wheel drive cars with short chassis' can be tons of fun with proper handbrake usage.
- There are disadvantages, though.
- In Front wheel drive cars, the engine is almost always placed in a transverse configuration, that is to say, it's put in sideways. While this reduces the amount of space the engine takes up in terms of the length of the car, it limits the size of the engine to at most, a V6 although most FWD cars on the road these days use a four cylinder engine for fuel efficiency. Having a sideways engine also increases the turning radius of the car, making maneuvers like u-turns more difficult when you don't have a lot of space.
- Another thing about Front wheel drive cars, and this it really more of a performance issue, is that they tend to understeer. It usually happens at higher speeds but, for the uninitiated, if you've ever been in a situation where the car isn't turning as much as you think it should be, that's understeer.
- Lastly, Front wheel drive cars, especially ones with more powerful engines, have this funny little thing called Torque steer, where the car will try to turn if you accelerate too hard. Most cars are designed to make torque steer invisible to the driver, but to see it for yourself, go to a empty parking lot that looks flat, take your hands off the steering wheel, and floor it. What you'll see is that the wheel will start turning one way or the other.
- So that's it for front wheel drive cars, but what about Rear wheel drive?
- With its relatively simple design and better handling, Rear wheel drive was the de facto layout for most of the 20th century. Today, though, it's typically used in luxury and sports cars due to their more powerful engines. This is because, when you accelerate, the weight of the car shifts to the back. In a rear wheel drive car, this places most of the weight on the drive wheels, increasing traction and improving acceleration.
- Rear wheel drive cars also have the advantage of having a more even weight distribution across the car. This give cars of this configuration a big advantage over front wheel drive cars in terms of handling such as better braking, tighter turning radius, more grip in corners, and no torque steer: features that are very desirable in performance vehicles.
- However, the drawback that comes with rear wheel drive is the increased chance of oversteering (where the car turns more than the driver expects) under heavy acceleration. If the driver accelerates too much during a turn, the rear wheels may lose traction, causing the rear of the car to slide out, putting the car into a skid. As dangerous as it is, oversteer has been turned into a sport. Drivers intentionally put their cars into oversteer and slide around consecutive corners for as long and as tightly as they can. This is called "drifting".
- I mentioned before that rear wheel drive is a simpler design. While this is true, and generally means it is easier to maintain, it is also heavier. You may think that something being simple and heavy is somewhat counterintuitive, but the added weight is due to the larger size of the components. The increased weight, unfortunately, leads to poor fuel economy compared to the more conservative front wheel drive cars.
- Lastly, lets talk about four wheel drive.
- Now, what four wheel drive actually means can vary between types of cars. Some cars are primarily two wheel drive but can become four wheel drive, like pickup trucks and off road vehicles, while others are full-time four wheel drive. The full time four wheel drive systems are often found in performance cars and smaller SUVs. But, for all practical cases, they are effectively the same and most of the world refers to them as such.
- In terms of handling, performance, and traction, four wheel drive cars have, generally, most of the benefits of both front wheel drive and rear wheel drive cars. In fact, they even have some bonus benefits, such as nearly double the traction and the ability to be configured to act like either a rear wheel drive, a front wheel drive, or even somewhere in between. This makes four wheel drive the perfect system for high performance off roading, like rally sport.
- This smoking gun does have a downside, though. Because of how complex the system is, it increases the cost of making a vehicle with it and the costs of maintenance. In addition, while this type of car performs without rival off road, on a nice dry road it is less than ideal and consumes more fuel than either of it's two wheel drive cousins.
- In the end, none of this matters for most people, but here's the breakdown anyway. If you are just looking for a daily driver, chances are you are going to end up with a front wheel drive car. If you like off roading, you're going to get a four wheel drive. And if you like sports performance cars, you might get either a rear wheel drive or a four wheel drive car.
- I hope this little piece has helped you better understand the different types of drivetrains in cars and what to look for in your next car purchase.
a guest Jun 19th, 2011 68 Never
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