| Author |
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Jim
| | Posted on Thursday, October 10, 2002 - 04:41 pm: | 
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When I'm stuck in gridlock traffic I allow my mind to wander: You see cars that tout themselves as "All Wheel Drive". Is there any mechanical difference between "All Wheel Drive" and 4-Wheel Drive?
Or is it the same thing with a twist of marketing for flavor?
Inquiring minds want to know . . . |
Carter Simcoe (Carter)
| | Posted on Thursday, October 10, 2002 - 04:43 pm: |
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All wheel drive is what you have in your disco when the diff-lock is off, the power can only go to one wheel at a time but it can be any of the 4 (not limited to one axle). 4 wheel drive means you have the ability to send power to both axles simultaneously. |
John Lee
| | Posted on Thursday, October 10, 2002 - 04:54 pm: |
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There's no precise definition of 4WD or AWD, but I believe the common usage of the terms pertains to the ability to shift to low range. Cars like the Porsche 959 and the various Subaru's are described as "AWD" because they don't have low range capability. "4WD" usually pertains to vehicles that have low-range ability like our Land Rovers.
Again, not a precise definition. Just common usage by the auto industry. |
michael burt (Mikeyb)
| | Posted on Thursday, October 10, 2002 - 04:59 pm: |
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what i like to see is the marketing smarts that put the decal for "real time all wheel drive" on the back of the honda crv's...
well that is when i need it. real time. like all wheel drive comes in handy right now for a situation last week. |
muskyman
| | Posted on Thursday, October 10, 2002 - 05:25 pm: |
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well 4 wheel drive was first claimed by non other then FWD a wisconsin based company selling the first multi-driveaxle wagon . it reffered to the fact all the 4 wheels had drive potential.
if what the insurance company currently define the difference between AWD and 4WD says anything then as it is declared in my policy my scout is a 4 wheel drive because the primary drive mode is 2WD and both my outback was and Disco is classed and discounted as AWD.
then again Insurance companys are full of shit |
muskyman
| | Posted on Thursday, October 10, 2002 - 05:38 pm: |
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hows this for a classic "wagon" |
Alyssa
| | Posted on Thursday, October 10, 2002 - 05:47 pm: |
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There is a distinct difference between four wheel drive and all wheel drive. Four wheel drive implies the presence of a transfer box, ie. a high range and a low range. There are different types of four wheel drive:
Permanent...always in 4wd, drives on pavement in 4wd high, ability to drive on pavement in 4wd low in some models (like Discovery, Mercedes ML320, TLC)
Part-Time...on road, you drive in 2wd. most basic, no center diff, locks front & rear wheels together, can't be driven on pavement (Pathfinder, Rodeo, Xterra)
Full-Time...more advanced than Part-Time, Most of the time in 2wd on road, but can engage 4wd high on road, and 4wd low off-road. Also includes "automatic" 4wd, when vehicle decides whether added traction of 4wd is needed. (Expedition, Suburban, Navigator)
All wheel drive is 4wd with no transfer box. Most vehicles that use this system (Subaru, X5, RX300, Audi) are in 2wd until road conditions warrant 4wd. The Freelander is considered "Permanent" AWD because it is always in 4wd (although there may be bias toward the front in dry conditions). An AWD is generally all the 4wd anyone needs if they never drive off-road. AND, if you never drive off-road, an AWD vehicle is a much better choice than say, an XTerra, or other vehicle with Part Time 4wd, because those vehicles never allow you to drive on road in 4wd. (And think of all the times you drive on gravel, in rain, in snow, through sand, etc... on a daily basis ON THE ROAD).
And it goes on and on and on. There are obviously many more differences, but these are some of the major ones. |
Ken Dunnington (Ihwillys)
| | Posted on Friday, October 11, 2002 - 11:19 am: |
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This is not AWD, it is 4WD. It has a transfer case(2x4, N, 4x4), but does not have high/low range. I'd say that 4WD is a system that can lock the front and rear driveshafts together(as a Disco can and this '41 Dodge WC can), high/low range is irrelevant.
http://www.hemkosys.com/kenstuff/images/41WC.jpg
Ken |
Blue (Bluegill)
| | Posted on Friday, October 11, 2002 - 12:17 pm: |
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nice truck Ken
AWD is minivan
4WD is truck
wife's explorer is AWD with no low-range...aka minivan  |
Al Oliveira (Offroaddisco)
| | Posted on Friday, October 11, 2002 - 12:34 pm: |
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So by Blue's definition the Freelander is a minivan (I would call it a station wagon) and by Kens definition the 2002 D2 isn't 4WD but AWD and therefore a minivan. The same would hold true for the new Rangie so I guess Land Rover is now in the minivan market and has given up on off road vehicles in the North American market. That is unless someone can prove that the 2003 NAS D2 actually has the CDL nipple. |
Greg Davis (Gregdavis)
| | Posted on Friday, October 11, 2002 - 12:41 pm: |
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I concur with the low range (4WD) vs no low-range (AWD) description. That is how I have always differentiated(sp?) them anyway. |
R. B. Bailey (Rover50987)
| | Posted on Friday, October 11, 2002 - 12:42 pm: |
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Usually, but it depends on the details of the system used:
AWD means that it is like the Trooper or the Subaru when in normal conditions. Both use the rear wheels to drive, but have the ability to atomatically transfere a certain amount of tourque to the front when it is needed.
The Trooper, however, has the ability to lock into 4WD, where 50% of torque is going to each axle. This makes it sort of a cross over between AWD and 4WD.
The Discovery and other modern Land Rovers also drive around normally without true 4WD, but the difference is that there is no built-in tourque biasing between the axles. At any given moment you could be gettting an even distribution of power to each of the 4 wheels. In the real world, this rarely happens. To go off-road, you really need to lock it into 4WD.
So until you lock it up, you will be able to follow Subarus anywhere they can go. Then when they get stuck you know you will need your Diff-Lock soon. Why follow a Subaru? To intimidate it.
http://landrover.mrbaileyshistory.net |
Al Oliveira (Offroaddisco)
| | Posted on Friday, October 11, 2002 - 12:46 pm: |
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So then what about vehicles with VC's like the RRC and 4.0/4.6? There is no real locking of front and rear. |
Alyssa
| | Posted on Friday, October 11, 2002 - 12:51 pm: |
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Ken, your definition of 4wd explains PART TIME 4wd, which is what your truck has. While very effective, especially off-road, your truck has the most basic form of 4wd. High/Low Range is irrelevant, I suppose, but almost ALL vehicles with a transfer box (aka 4wd vehicles) will have the option to choose between high and low range. In fact, the ability to lock the front and rear driveshafts together is irrelevant, at least defintion-wise, with regards to whether or not a vehicle is 4wd. |
Leslie N. Bright (Leslie)
| | Posted on Friday, October 11, 2002 - 01:00 pm: |
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R.B.,
I've not seen a Disco that could keep up w/ the Roo to intimidate it on pavement..... NOTE: ON PAVEMENT!
lol.....
-L |
Blue (Bluegill)
| | Posted on Friday, October 11, 2002 - 01:10 pm: |
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Quote:So by Blue's definition the Freelander is a minivan (I would call it a station wagon) and by Kens definition the 2002 D2 isn't 4WD but AWD and therefore a minivan. The same would hold true for the new Rangie so I guess Land Rover is now in the minivan market and has given up on off road vehicles in the North American market. That is unless someone can prove that the 2003 NAS D2 actually has the CDL nipple.
yes, exactly |
Milan
| | Posted on Friday, October 11, 2002 - 01:12 pm: |
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AWD - no ability to lock front and rear driveshafts together = differentiation between front and rear driveshafts, usually no low range, most of the time no transfer case either.
4WD - ability to split torque between front and rear 50/50.
Part-time - no ability to differentiate front to rear.
Full-time - ability to differentiate front to rear; basically part time with AWD mode added.
Permanent - LR's take on Full-time.
RangeRover with viscous coupling is really an AWD with a low range added. So is a D2 with no CDL. |
Ken Dunnington (Ihwillys)
| | Posted on Friday, October 11, 2002 - 01:12 pm: |
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First, not my truck, wish it was...
Second, yep, it's a stickler. I just thought I'd throw in an example of a single speed transfer case that is 4WD. I mean if that truck is not 4WD...
Also, an open diff splits torque equally between the two outputs 100% of the time. This fact catches a lot of folks off quard(don't mistake power for torque). When you lock a diff, you now allow UNEQUAL torque distribution.
Ken |
Milan
| | Posted on Friday, October 11, 2002 - 01:17 pm: |
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The way I see it, you put 100% torque to the center diff or t-case. What comes out of the t-case is either 100% rear (in part-time) or 50/50 in 4wd (CDL locked or part-time in 4wd) or anything else in AWD. |
Ho Chung (Ho)
| | Posted on Friday, October 11, 2002 - 01:22 pm: |
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cabernet! |
Milan
| | Posted on Friday, October 11, 2002 - 01:29 pm: |
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I should have added that part time by default has a 2WD mode (usually RWD but could be FWD). Part-time means 4WD mode is only used part-time (only when you engage it). |
todd slater (Toddslater)
| | Posted on Friday, October 11, 2002 - 11:05 pm: |
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What about diff's. the only true 4 wheel drive locks all three, anything else is...well not. And if your head is spinning like mine go here:
http://home.attbi.com/~eliot_www/awd.html
it gets worse |
Milan
| | Posted on Saturday, October 12, 2002 - 11:34 am: |
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On flat ground with traction, all 4 wheels are powered even if you have open diffs. Hence the term AWD or 4WD. The fact that one wheel can brake loose is inconsequential. Without lockers you just don't have 4WD all the time. |
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