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Thread: Rear drive, front drive or all-wheel-drive?

  1. #1
    Vulture of The Western World Eric's Avatar
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    Rear drive, front drive or all-wheel-drive?

    Should you buy a rear-wheel-drive car, a front-wheel-drive car - or an all-wheel-drive car? The answer depends on what kind of a driver you are, the conditions you typically drive in - and what you expect the car to be able to do best.

    Here are the main pros and cons of each layout:

    * Rear Wheel Drive -

    There are two main advantages to owning a RWD car. The first is that RWD is both simple and rugged - especially if it's a solid axle design - and can take a lot of abuse without needing expensive repairs. Accidentally run over a curb in a solid axle RWD car, for instance, and you probably won't break anything. But hit a curb (or even a deep pothole) in a FWD car and the odds are much higher that something expensive will be damaged. This is why cop cars and other "service" vehicles are overwhelmingly RWD.

    The other advantage RWD cars offer is better balance - and because of this, better handling. While a FWD car has most of the weight of the engine and transaxle (the transmission and axle assembly are one unit in a FWD car) over the front wheels, a RWD car spreads the weight of its drivetrain more evenly front-to-rear. This is why most sports cars - and virtually all race cars - are RWD.

    And cons? As anyone who has owned one will tell you, RWD cars are at their weakest in poor weather - rain and snow. Even with modern traction control, a RWD car is more prone to loss of traction on slick roads. In snow, RWD cars are best left home.

    * Front Wheel Drive -

    As with RWD, FWD offers two main advantages - just very different ones. The first is economy. It is cheaper to design and build a FWD car. There are fewer parts - and the drivetrain is easier and cheaper to install as the car rolls down the assembly line. FWD also helps cut down the car's weight by eliminating the separate transmission and axle assemblies used in a RWD car. This, in turn helps the car get better gas mileage. This is why FWD is most commonly found in economy-type and lower-cost cars.

    The other FDW plus is better traction than a RWD car can deliver - especially in rain and snow. The front wheels pull the car instead of the rear wheels pushing it. And, the weight of the engine/transaxle sits on top of the (front) drive wheels, which further helps the car get a grip. FWD cars are typically very capable in poor weather - even excellent, when fitted with snow tires.

    Cons? FWD cars are nose-heavy, which isn't optimal for handling - especially high-speed, high-load handling. A related problem is that the front wheels have to do two things at once - put the power to the ground and steer the car. This, too, is not optimal for a performance/sporty car. In a high-powered FWD car, it can sometimes be difficult or awkward to keep the car pointed straight ahead as the car accelerates. The front wheels may jerk to the left or right - a problem called "torque steer." Modern FWD cars are less prone to this thanks to electronic traction control, but it's still not the hot set-up for performance applications - which is why very few "serious" performance cars are FWD.

    The final thing to know about FWD is that it's relatively fragile. Half-shafts and constant velocity (CV) joints are more susceptible to injury than a rugged lump of cast iron - as in a RWD car's solid axle. While a RWD car's axle may outlast the car and never require service beyond the occasional lube change, it is far more likely that a FWD car will need new CV joints/boots or something else as the years roll by.

    * All Wheel Drive -

    The best thing about AWD is that it gives you some of the advantages of both RWD and FWD - while minimizing the weaker points of either of those layouts.

    The number one advantage of AWD is excellent traction - both on dry pavement and in poor weather. This is why AWD appeals to both the performance-minded enthusiast as well as the person who just doesn't want to get stuck in the snow. Some AWD systems are based on RWD layouts (examples include the Mercedes Benz E-Class) while others are built around FWD layouts (such as any new Subaru). The RWD-based versions are usually more performance-oriented but all AWD vehicles do an impressive job of balancing handling/driving dynamics with "go anywhere, anytime" bad weather capability.

    But there are downsides - the two biggest ones being weight and cost. AWD cars can weigh several hundred pounds more than an otherwise identical RWD or FWD car. This hurts the car's acceleration - at least, when compared with an otherwise identical RWD or FWD version of the same car. And the added weight means the car will use more fuel - especially if the engine's power has been increased to compensate for the added weight.

    The last downside with AWD is the cost. AWD, when offered as an option, usually adds significantly to the car's sticker price. If it's standard equipment, the car will usually cost more than otherwise equivalent FWD or RWD cars. And because there are more components, there are more things that will need to be serviced - and which may eventually fail and hit you up with a big bill as the car gets older.

    So, you'll pay more up front - at the pump - and down the road. But that may be worth not getting stuck every time it snows - and still being able to tear into corners when it's nice out.

  2. #2
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    There are blends of the systems out there too.

    The part-time 4WD system used in the CR-V is primarily a FWD one, but there is a propeller shaft running to the rear differential that turns at the same speed as the front axles. When the rear differential senses a difference in rotational speed between the propeller shaft and rear axles (it uses two hydraulic pumps & internal check-valves to do this), it engages a clutch to provide power to the rear wheels too.

    Advantage: Being FWD 98% of the time means that you get good fuel economy.
    Disadvantage: Unless the front wheels are spinning, no power is sent to the rear.

    Chip H.

  3. #3
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    I prefer rear wheel drive although most of my car purchases have been FWD.

    There are not enough RWD cars on the market to choose from. Now that the auto industry is in the tank worldwide and that CAFE rules are going to take effect in a couple of years, it looks like I won't have the choice of purchasing a reasonably priced midsized RWD seadan unless I want to get a 5 year old BMW or a 3 year old G35. I don't really like the G35 since it has a gas gobbling 3.5 L V6 that burns almost as much as a 4.0L V8.

    I would only consider an AWD car if I lived in snowy climates. The only exception to that is the Subaru Legacy GT, which is a solid, bulletproof, handling vehicle. I have heard, however, that they can be really hard on gas, although reports vary.

  4. #4
    Vulture of The Western World Eric's Avatar
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    Quote Originally Posted by swamprat View Post
    I prefer rear wheel drive although most of my car purchases have been FWD.

    There are not enough RWD cars on the market to choose from. Now that the auto industry is in the tank worldwide and that CAFE rules are going to take effect in a couple of years, it looks like I won't have the choice of purchasing a reasonably priced midsized RWD seadan unless I want to get a 5 year old BMW or a 3 year old G35. I don't really like the G35 since it has a gas gobbling 3.5 L V6 that burns almost as much as a 4.0L V8.

    I would only consider an AWD car if I lived in snowy climates. The only exception to that is the Subaru Legacy GT, which is a solid, bulletproof, handling vehicle. I have heard, however, that they can be really hard on gas, although reports vary.

    I am a big fan of Soobies - but you've heard right,they are gas pigs. Every single one I have test driven over the past 10-plus years absolutely drank gas.

  5. #5
    DonTom
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    Wouldn't it make more sense to compare AWD with 4WD than with FWD or RWD?

    BTW, isn't a clutch job a lot cheaper (and less hassle) on a RWD than on a FWD?

    -Don- (Reno, NV)

  6. #6
    Vulture of The Western World Eric's Avatar
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    Quote Originally Posted by DonTom View Post
    Wouldn't it make more sense to compare AWD with 4WD than with FWD or RWD?

    BTW, isn't a clutch job a lot cheaper (and less hassle) on a RWD than on a FWD?

    -Don- (Reno, NV)
    I thought about it but decided to keep the topic confined to cars.

    No cars come with (true) 4WD.

    But it's confusing to make the distinction because several automakers call their AWD systems 4WD.

    And yes, it is much easier to do a clutch job on a RWD vehicle. Dropping the tranny is literally just a matter of undoing a few bellhousing bolts, dropping the driveshaft and rear crossmember. Once the tranny is out, accessing the flywheel, etc. is a snap. Everything is right in front of you.

    I haven't done a clutch job on a FWD vehicle but I bet in many cases you'd have to pull the entire engine/transaxle assembly - and there's much less room to get to things, too.

  7. #7
    DonTom
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    Quote Originally Posted by Eric View Post
    No cars come with (true) 4WD.
    I never even realized that until you mentioned it. Why is that?

    -Don- (Reno)

  8. #8
    Vulture of The Western World Eric's Avatar
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    Quote Originally Posted by DonTom View Post
    I never even realized that until you mentioned it. Why is that?

    -Don- (Reno)

    Well, here's where it gets confusing:

    4WD used to refer pretty much exclusively to a truck-type system with a transfer case and Hi/Low range gearing. Most of these systems are part-time, and operate in RWD until the 4WD is engaged. And when the 4WD is engaged, the power split is typically - I think always - exactly 50-50.

    They are designed for off-road work - and for driving in heavy snow/mud, etc. True, truck-type 4WD is not the hot ticket for use on dry/paved roads. Indeed, you can mess up the system by running in 4WD on dry paved roads.

    That said, some cars with AWD are described as being 4WD, which is technically correct in that power does go to all four wheels under certain conditions. However, there is no transfer case, and thus no High or Low range gearing. The power split also varies, with as much as 90 percent of the power going to either front or rear, depending on traction. But it does not stay constant, typically anyhow.

    The main thing to know is that AWD is designed for on-road use primarily. This is why it's an aid to high-speed handling in sporty cars like the Mitsubishi EVO and Subaru WRX.

  9. #9
    DonTom
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    "Indeed, you can mess up the system by running in 4WD on dry paved roads."

    Except in my 1997 Jeep Cherokee which is true 4WD at all times.

    It often snows here in the Reno area (but just a lot of rather warm rain lately!).

    But I am thinking road use and snow. I would think cars with true 4WD should be possible and useful around here. I hear a lot of bad things about AWD about how it will sometimes engages when you don't want it to.

    Tom's brother has a AWD Dodge Durango. I've driven it and I think I have felt it engage during a slow speed turn and it didn't seem natural. Sort of jerked hard. Was that the AWD engaging?

    -Don-

  10. #10
    Senior Member bikerlbf406's Avatar
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    I have owned a variety of FWD, RWD & part time 4WD vehicles. As far as AWD vehicles, I havent owned any. My new Explorer is the closest to an AWD vehicle I have had, which is a full time 4WD drive with auto, 4 high or 4 low settings. Most of my RWD vehicles have been trucks & all of the 4WD vehicles have been SUV's. For economics I prefer FWD, however if its deep snow (once in a while during the winter season) then they run the risk of getting stuck. RWD though tends to have a lighter rear end & slide around a little to much during the winter. 4WD seems to be the best all around vehicle, but can definately hurt the fuel economy when dealing with a bigger 6 cylinder as it is. As far as Subaru's are concerned, my parents owned a '91 Subaru Legacy & I owned a '96 Subaru Legacy, both were excellent on gas getting an average of 25mpg in the city. Of course both of them were the more of a rareity with FWD & not AWD; so the AWD ones may be worse on gas, dont know first hand though. The FWD Legacy's were great on gas though.
    Tim, proud owner of 2001 Chevrolet Silverado 1500 & 2007 Honda CMX250C Rebel


  11. #11
    Vulture of The Western World Eric's Avatar
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    Quote Originally Posted by DonTom View Post
    "Indeed, you can mess up the system by running in 4WD on dry paved roads."

    Except in my 1997 Jeep Cherokee which is true 4WD at all times.

    It often snows here in the Reno area (but just a lot of rather warm rain lately!).

    But I am thinking road use and snow. I would think cars with true 4WD should be possible and useful around here. I hear a lot of bad things about AWD about how it will sometimes engages when you don't want it to.

    Tom's brother has a AWD Dodge Durango. I've driven it and I think I have felt it engage during a slow speed turn and it didn't seem natural. Sort of jerked hard. Was that the AWD engaging?

    -Don-

    My own opinion here:

    Unless you need to deal with severe off-pavement driving (mud, deep snow, rutted gravel roads, etc.) truck-type 4WD is a waste of money both up-front and as you drive.

    You spend more to buy it, the vehicle weighs more (which hurts performance as well as uses more fuel) and you will probably never or almost never need the two-speed transfer case and 4WD Low range gearing such systems usually have.

    AWD is superior for on-street use. Some of these systems, in addition to shifting power to the front or rear axles as traction changes, can also route power (or limit slip) at individual wheels.

    Also, AWD offers a handling advantage under high-performance conditions on dry, paved roads that truck-type 4WD does not. If anything, truck-type 4WD is a handling handicap on dry, paved roads...

    One caveat: Trucks and SUVs can almost always tow considerably more than an AWD-equipped car or crossover.
    Last edited by Eric; 03-02-2009 at 08:32 AM.

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