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Initial D World - Discussion Board / Forums > Technical Discussion > AWD And 4WD


Posted by: Sti_Brumby Mar 16 2005, 11:44 PM
Full time four wheel drive (not to be confused with: part time 4WD ) is a system that powers all four wheels at all times. Each tire gets about 25% of the available torque when the ground is level with a consistant surface. Driver has a choice of a "4-high" (that's your every day setting) and "4-low".

When "4-low" is selected the wheels receive substancially more torque (on a Grand Cherokee its 2.72 times more) than in "4-high" - at the same time the vehicle moves at substancially slower speeds (2.72 times slower on J GC).

The low setting is an advantage for drivers who need to tow and maneuver a heavy trailer etc and for drivers who at one point or another may want to negotiate difficult off-road terrain.


All wheel drive is a system that powers all four wheels of a vehicle at all times as well. Difference to full time 4WD is that a "4-low" setting is not available. Due to the lack of "low range" AWD vehicles are much less capable in off-road settings than 4WD vehicles.



Recently some new "automatic" AWD systems have emerged. Fancy names like "Real Time 4WD" are hiding the fact that they are essentially sophisticated 2WD systems. They should be called part time AWD systems. They cannot claim the same (minimal) safety and traction advantages of full time 4WD. They are much less capable in off-road settings than full time AWD systems and inferior to full time 4WD. However, automatic AWD is becoming more and more sophisticated and offers pretty much everything consumers expect for everyday (pavement) driving.

Here is how they work: During traction loss on the driven axle (could be front or rear) a fully automatic system (hydraulic, mechanical or electronic) routes torque to the axle with traction. This means you have to completely lose traction in 2WD on your driven axle first and then the other axle will take over and try to keep the car moving. So, for a moment you have 4WD (AWD). Doesn't mean much because only two wheels have traction. Once the driven axle regains traction and both axles rotate at the same speed again, the system moves back to 2WD.


w00t2.gif Finshed

Posted by: BOZZ Mar 17 2005, 12:20 AM
Since you are on the topic of AWD vs 4WD... I want to post something that Frost has posted elsewhere about the same issue...

======================================================

For some bloody reason, people are still very much confused about the rather large differences between All-Wheel-Drive (AWD) and Four-Wheel-Drive (4WD - this includes both part time, full-time, Nissan's ATTESA, Honda's stupid Real Time).

Here's the perfect article by Graeme Fletcher, a respected journalist and wheel-head. You've seen him on the Motoring 2004 series on TSN and his credentials speak for themselves.

The difference between four- and all-wheel drive
By Graeme Fletcher - National Post

Friday, May 07, 2004

The key advantage to driving all four wheels is the added ability it can impart to the vehicle. Rather than having to push 50% of the horsepower and torque through each of the front or rear wheels, the system divides the power among all four. This not only reduces unwanted wheelspin, it improves traction on wet pavement and loose surfaces and, perhaps more importantly, whenever traction is temporarily compromised -- such as encountering debris (sand and the like) or a slick spot (oil or ice) on the road.

This description applies to both four- and all-wheel-drive systems. However, this is where the confusion tends to come into play, simply because the terms are bandied about with little or no regard for the significant differences between one system and another. Four- and all-wheel drive are best differentiated according to whether or not the system has a low-range gear set -- in my book, four-wheel drive does; all-wheel drive does not.

Four-wheel drive is generally used on SUVs and pickup trucks, and can be split into two very different groups -- part-time and full-time. The former is exactly as described -- part-time in that it is to be used only on a slippery surface, which is not very much of the time because engaging it on a dry, high-traction surface can cause damage to the drivetrain.

Locking the centre differential (which happens whenever the system is engaged) prevents the rotational speed differences between the front and rear axles (caused by cornering) from being dissipated and so the drivetrain begins to wind up. Driving a part-time system in a circle on dry pavement when engaged causes the vehicle to buck as it tries to spin off the windup by breaking loose one or more of the wheels.

Part-time systems also entail driver input to activate, which further compromises its effectiveness. For example, most highways are ploughed and free from snow during winter. However, many off-ramps are still slippery and so the part-time system must be activated and deactivated according to the changing conditions. The problem with this is that the action invariably comes too late to be of any real benefit, as all part-time systems have a speed above which they cannot be engaged -- some as low as 40 kilometres an hour, which is just too slow to be of value in the off-ramp scenario.

A full-time four-wheel-drive system can be engaged on a dry surface and usually includes an automatic mode. However, most only drive one set of wheels until they begin to slip, at which point the system automatically begins to transfer some of the power to the other wheels. Typically, these systems are referred to as on-demand systems. While of value on a slippery hill or ploughing through snow, they tend not to add to the dynamic ability of the vehicle. This is what separates the on-demand types from true all-wheel-drive systems.

Consider an on-demand system that only drives the front wheels until they begin to slip. In a corner, the vehicle tends to understeer when the front wheels lose grip. Now, shifting some of the drive rearward momentarily pushes the vehicle further into the understeer condition until the front wheels regain grip. That can be scary.

Conversely, the all-wheel-drive systems employed in the new Subaru Legacy power both the front and rear wheels all the time. In most cases, this means sending more power to one set than the other. Depending upon the model, the manner in which this is accomplished varies -- the system tied to the manual transmission is good (it uses a viscous couple to accomplish the power transfer); the one tied to the automatic box is better -- simply because it is more progressive and proactive, which means more balanced.

In the base Legacy, the system married to the automatic uses an electronically controlled clutch pack to distribute the power between the front and rear wheels. Normally, it sends 60% to the front wheels and 40% to the rear. This brings two advantages: First, the extra weight over the front wheels (about 60% because of the engine and transmission) makes it possible to fire more power through them than to the rear wheels before wheelspin becomes an issue. In essence, the weight bias cancels out the drive bias, giving an effective 50/50 split. If any of the wheels do spin, the centre differential locks to deliver a real-time 50/50 split. The second bit is more about preference than ability, as it allows the car to understeer at the edge of the traction limit, which is less disconcerting than oversteer to most drivers.

The system employed in the range-topping GT is better if you want a truly engaging drive. Under normal circumstances, the system sends 45% of the power to the front wheels and 55% to the rear, which imparts a sportier feel because it is possible to hang the tail out. It can lock the differential to split the power evenly if that's the best strategy. But this is the proactive part -- mat the gas and the system recognizes the urgency and automatically locks the system to prevent the back end from fishtailing. Once up to speed, it relaxes its hold, which allows the driver to hang the rear end out. It only intrudes when the driver steps beyond his ability -- my sobering moment came half way around the Cabot Trail in the midst of a torrential downpour.

Regardless of the type, the Legacy's handling is helped by the fact that all of the systems Subaru employs are symmetrical about the centre line of the car. This balances the weight left to right (many are forced to offset the weight in order to package the system) and allows the use of equal-length drive shafts, which banishes torque steer; this in spite of the GT's 250 pound-feet of torque.

<End of article>

For those of you who've read my other explanations, you'll realise I've been saying exactly what Mr. Fletcher here has just said. I have not tried out nor know much about the system in use for Volvo's AWD systems but from initial research, I hear under normal circumstances, the car will have 99% power to the front 2 wheels. Again, I seriously dislike this idea for the same reasons Mr. Fletcher said. The perfect AWD car for daily driving in my mind, would be a 50-50 final bias (drive AND weight combined). This means that in the case that I DO lose traction on any 2 wheels (front pair or rear pair), I have at least 50% power on the road at THE INSTANT OF TRACTION LOSS. For the system by Volvo, if I lose traction in the rear, no problem, it should have 99% power upfront. But how often do you run into situations where your rear loses traction before the front in normal driving conditions? Rarely. Normally your front goes out (simply because it is the FRONT and your car drives FORWARDS into any territory). So say I run into an ice patch. At the INSTANT I hit the patch, the car has 1% power delivery AT THAT INSTANT. While this may be for only 0.001 seconds or what not, the car still has to respond considerably before 50% of the power is diverted to the rear. Also, by suddenly sending most of the power to the back where it normally is almost never present, we are effectively switching cars on the driver. The car will behave differently and the driver will attempt to compensate which in turn will make the car compensate which in turn will make the driver compensate which in turn will... you get the idea. Even Mr. Fletcher agrees on this.

By having a 50-50 split (final), when I hit an ice patch, at THAT INSTANT, I have 50% power to the rear, which means that the car will feel 'weaker' (in sense of acceleration vs. amount of gas pedal pushed in). Let's assume this perfect AWD car can send up to 99% to the rear, it is still only a +49% increase from normal situations as opposed to the +98% increase by Volvo's system. That is HALF the power that is sent to the rear compared to the Volvo! This means that the sudden extra power in the rear will not affect the driver as greatly as Volvo's system does which goes back to the point of driver-car-driver-car compensation loop.

Generally, I dislike how the AWD name is being haphazardly tagged onto vehicles that really should not be tagged by such a name. I believe Volvo is making a serious mistake in doing so but who am I to argue against the mighty corp?

Anyways, I hope you all learned something. Cuz I'm sick of explaining it to everyone, especially the so-called EVO or WRX / STi experts who don't know shit about AWD and 4WD systems yet can still call themselves experts.

Frost

======================================================

Posted by: DGoReck Mar 17 2005, 08:40 AM
Good post, the article hits a lot of things head on. And tell me, it upsets me more and more when I am reading things on these cars wtih their 'AWD' system like that volvo which is 'basically' FWD till the system reacts.

I could not explain any of that better in my own words.

This should be a sticky.

Posted by: Lakersfanman33 Mar 17 2005, 11:28 AM
I second the sticky request, shoes the difference between many disputed topics.

Posted by: BOZZ Mar 17 2005, 12:31 PM
Yeah it should definetly be stickified... I know up until Frost set the record straight I thought AWD = 4WD...

Posted by: sideways Mar 17 2005, 02:22 PM
Itll get a sticky but im going to move it to the tech as well

Posted by: VRr1FD Mar 17 2005, 02:31 PM
you've got to be f**king kidding me. ever wonder why there are almost as many kinds of 4wd systems as their are names for them? marketing. sure, they work differently, but they are all 4wd, they are just named by each manufacturer AFTER they are created. that's the key, all these names and terms are created after the system is made to differentiate it, to make it sound more special. but it's all 4wd.


4wd
4x4
AWD
SHAWD
ATTESA
full time 4wd
symmetrical AWD
quattro
super mega awesome magic traction
ETC. ETC. ETC.

just change a differential style here or there, all the sudden you have an entirely different 4wd system!!! better come up with a new name for it!

it's all BS.

my STi is 4wd, yay. it uses 3 lsd's and is full time, it's still 4wd. you know why? because 4 wheels get drive power! which is exactly what 4wd means. i know, it's crazy.

Posted by: sideways Mar 17 2005, 02:41 PM
Ive always been under the impression that 4wd sends the power at a constant rate to the wheels- where awd can send varying amounts of power between the front and rear wheels as needed

Posted by: VRr1FD Mar 17 2005, 02:43 PM
QUOTE (BOZZY @ Mar 17 2005, 12:20 AM)


Generally, I dislike how the AWD name is being haphazardly tagged onto vehicles that really should not be tagged by such a name. I believe Volvo is making a serious mistake in doing so but who am I to argue against the mighty corp?

Anyways, I hope you all learned something. Cuz I'm sick of explaining it to everyone, especially the so-called EVO or WRX / STi experts who don't know shit about AWD and 4WD systems yet can still call themselves experts.


yeh, how dare volvo call their FWD system AWD!!!

it's almost as stupid as Nissan calling the ATTESA system AWD or lambo and as far as i know, Porsche, calling their silly RWD systems AWD. rolleyes.gif

know what i really hate though? torsen and electronic center diffs that sense slip before the tire even begins to actually slip and instantaneously change the torque split! damn reactive crap, it should just be a locked center diff for the best handling!!!


good thing you learned me though.


f**king same old pointless crap, it's pure semantics. we might as well bring up the good old motor/engine debate.

4wd=4wd.

QUOTE (sidewaysgts @ Mar 17 2005, 02:41 PM)
QUOTE
Ive always been under the impression that 4wd sends the power at a constant rate to the wheels- where awd can send varying amounts of power between the front and rear wheels as needed


if you need to think that way to fit some sort of need for categorization, then so be it. but the truth is, the correlation of "AWD" systems normally using non locked center differentials is a rather after-the-fact reason.

let me put it this way

1. company makes 4wd system
2. company uses unlocked center diff
3. company calls it AWD
4. there for all AWD systems have unlocked center diff.

4 is where the logical fallacy comes in. there is a term for giving a word for this but i have not been able to think of it. the fact is, there are so many kinds of 4wd systems that to try and lump them into groups is just silly. it's best to just drop all the assumptions and asinine terminology and address them individually based on how each works. all these marketing terms were just created out of thin are, so it's pretty stupid to try and argue the differences of these made up terms as if it meant anything.


-edit. i mean, call it what you want, but don't expect the terminology to be gospel. so there is no point in a "ok this is what all these terms mean, this is how each is different" tread. and damn sure no point in acting like you know something special because you wasted your time be studying marketing terms. if you want to point out the difference of actual systems, fine, but associating the systems with their stupid marketing terms is over the line of logic.

see what you did? you made me double post. laugh.gif

Edit by SidewaysGts: Double post fixed tongue.gif

Posted by: BOZZ Mar 17 2005, 05:09 PM
Don't mean to agitate you any further VR1... But just was reading up some articles... Apparently 4WD can be switched to 2WD, is this true?

From about.com:

4 x 4 (4WD) - Describes a vehicle with four-wheel drive. The first figure is the number of wheels. The second is the number of powered wheels.

4 x 2 (2WD) - Refers to a two-wheel drive vehicle with four wheels. The first figure is the number of wheels. The second is the number of powered wheels. With a 4x2, engine power is transmitted to only two wheels, usually the rear.

Part-Time 4WD - Refers to a four-wheel drive system that operates on-demand and drives all four wheels by locking front and rear axles together via a shift lever. It usually includes two speed ranges (Hi and Lo). Part-time 4WD systems must be operated in 2WD mode on dry pavement, as they're designed to be used only in specific situations when extra traction is required.

Full-Time 4WD - Describes a four-wheel-drive system that can be operated continuously on all surfaces. A full-time four-wheel-drive system may include the option of part-time operation (allowing you to shift into 2WD on dry pavement for example), and may or may not have Hi and Lo speed ranges.

Automatic Four-Wheel Drive (A4WD) - This type of drive system automatically engages 4WD as needed. When internal monitors sense differences in individual wheel speeds, indicating that a tire is slipping, then 4WD is automatically engaged.

Shift on the Fly - This type of system allows manual shifting from 2WD to 4WD Hi without coming to a stop. Most systems have a speed limit at which you can engage the system; typically it's under 60 mph.

All-Wheel Drive (AWD) - A full-time single-speed system designed to supply drive power to all four wheels. The percentage of front/rear power delivery varies from system to system.

Again... apologies... I don't want to antagonize you or anything... I just want to ensure I know what the hell is 4WD and AWD...

Posted by: sideways Mar 17 2005, 05:39 PM
Basicly put, part time 4wd lets the driver select the car INTO 4wd mode. If its a manual theres actualy a 2nd stick to control- automatics often have a seperate lever or buttons you can press to engage it.

I wont argue much with you VR because i know exactly what your talking about, either wya you look at it all the wheels are being powered.

i WILL ask you this though, see if you can find a vehicle marketed as awd with a locked center dif tongue.gif laugh.gif Anything with a varying dif in the center from what IVE SEEN so far (i havent done huge research into this) is considered "awd". The ones ive seen as 4wd have always had a locked dif.

Imo just makes things a little easier to go along this basis when your telling someone something about your car

Posted by: Frost Mar 17 2005, 05:40 PM
QUOTE (VRr1FD @ Mar 17 2005, 02:43 PM)
  yeh, how dare volvo call their FWD system AWD!!!

it's almost as stupid as Nissan calling the ATTESA system AWD or lambo and as far as i know, Porsche, calling their silly RWD systems AWD.  rolleyes.gif

know what i really hate though? torsen and electronic center diffs that sense slip before the tire even begins to actually slip and instantaneously change the torque split!  damn reactive crap, it should just be a locked center diff for the best handling!!!


good thing you learned me though.


f**king same old pointless crap, it's pure semantics.  we might as well bring up the good old motor/engine debate.

4wd=4wd.

QUOTE (sidewaysgts @ Mar 17 2005, 02:41 PM)
QUOTE
Ive always been under the impression that 4wd sends the power at a constant rate to the wheels- where awd can send varying amounts of power between the front and rear wheels as needed


if you need to think that way to fit some sort of need for categorization, then so be it. but the truth is, the correlation of "AWD" systems normally using non locked center differentials is a rather after-the-fact reason.

let me put it this way

1. company makes 4wd system
2. company uses unlocked center diff
3. company calls it AWD
4. there for all AWD systems have unlocked center diff.

4 is where the logical fallacy comes in. there is a term for giving a word for this but i have not been able to think of it. the fact is, there are so many kinds of 4wd systems that to try and lump them into groups is just silly. it's best to just drop all the assumptions and asinine terminology and address them individually based on how each works. all these marketing terms were just created out of thin are, so it's pretty stupid to try and argue the differences of these made up terms as if it meant anything.


-edit. i mean, call it what you want, but don't expect the terminology to be gospel. so there is no point in a "ok this is what all these terms mean, this is how each is different" tread. and damn sure no point in acting like you know something special because you wasted your time be studying marketing terms. if you want to point out the difference of actual systems, fine, but associating the systems with their stupid marketing terms is over the line of logic.

see what you did? you made me double post. laugh.gif

Edit by SidewaysGts: Double post fixed tongue.gif


I don't like how Nissan calls their ATTESSA an AWD system either. ALL WHEEL DRIVE as the name implies, means all wheels driving at any given point. If the thing is RWD until traction is lost, then it isn't all wheel powered all the time is it? It's just a Full time 4WD system.

It's not semantics. It's downright misleading by the marketing people. If I sell you a V8 engine that only fires 4 of it's cylinders most of the time until it requires more power, is it really a plain old V8?

I've driven clunky old regular 4WDs that required me be at a stop, change the system manually with the shifter and then slowly gas to get out of whatever trouble I was in (usually stuck in sand since it was the desert we were in). Once I got out of trouble though, I HAD to slap it back into normal driving or else I run the risk of really blowing the tranny or the driveshaft. I forgot once and when you turn the B*tch, it JUMPS and HOPS. Learnt my lesson well.

Never had the same problems with AWD systems though.

Frost

Posted by: PlastikmaN Mar 17 2005, 05:41 PM
alright good to know!

thanks i was a bit confused

Posted by: sideways Mar 17 2005, 06:04 PM
QUOTE
If I sell you a V8 engine that only fires 4 of it's cylinders most of the time until it requires more power, is it really a plain old V8


Itd still be a v8 imo, just a really advanced one wink2.gif

Just like i consider the attessa system to be awd, just a very advanced version of it. Its either locked in the center, or its not. No need to over complicate matters tongue.gif

Posted by: Sti_Brumby Mar 17 2005, 07:13 PM
I used to use 2wd/4wd in my brumby before the Sti conversion. 4wd and awd are different. blink.gif. Reason being as a 4wd Cannot be driven on dry roads or any road infact without putting great strane on the Gear box.

Here's some things copied from a website

4WD refers to part time systems, which run in 2WD on pavement, and
on which you only engage the other axle (mostly front axle, but there are
exceptions) when extra traction/stability is needed. Most (but not
all) of these are heavy offroad vehicles with a split gear T-case
(high/low range). Most (but not all) have a separate frame. Most (but
not all) have solid axles.

Full Time 4WD [RAV4] are those systems which send torque to all
wheels all the time, without user interference or axle-engaging
automagic systems to achieve that. *Additional* user interference
(center diff lock as the most common [RAV4 5sp manual]) and
*additional* automagic systems (viscous LSD on center diff mostly
[RAV4 auto]) can be present. No real distinction between road-going
vehicles and heavy offroad vehicles; both often have full time 4wd
(but again only the latter will have a split gear T-case).


AWD (All Wheel Drive) is the least defined category; often it includes
the full time 4wd category, but I tend to define it more strictly as
those vehicles that *only* send (a significant amount of) torque to
the other axle (mostly rear axles, only a few front axles) *after*
slip occurs. This behaviour is in contrast to full time, where all
wheels get torque all the time, and at least with a fairly even
balanced split (50/50% up to 33/66%, but much more bias than that
makes it rather AWD than full-time.




And More

4WD = Low range and High Range gearing
AWD = Only high range gearing

Part-time 4WD: No centre differential. Cannot be used on dry/wet, semi-slippery roads due to the lack of the centre differential. When activated, both front and rear axles are physically locked to each other and have to spin at the same rate. This becomes a problem when turning on sufficiently high friction surfaces. Examples: Suzuki SUVs, most 4WD pickup trucks, cheaper SUVs.

Permanent 4WD:. No two wheel drive mode. System is equipped with a centre differential, and hence is safe to use on all surfaces. All four wheels are powered all of the time (usually 50/50 front and rear axles). This is arguably the best system since the torque split ratio does not change and is the most predictable. All wheels "help out" all of the time and this stabilises the vehicle + improves handling. With the extra two drive wheels, the vehicle has twice the amount of traction all of the time (even in no-slip conditions) vs. a 2WD vehicle. Examples: MB M-class SUV, the Range/Land Rovers.

Full-time 4WD: Basically permanent 4WD but with a 2WD mode. This was born out of customer demand (for a 2WD mode). Examples: Toyota Sequoia, Mitsubishi Montero.

Permanent AWD: Basically permanent 4WD but without low range gearing. Examples include the Audi Quattro AWD system, the MB's 4-matic AWD system, Subaru's manual transmission AWD system.

Full-time AWD: System is active at all times, however in most cases, the one set of wheels (usually the rears) only receive 5-10% of the engine's power unless slippage occurs. At that point, power is progressively transfered to the opposite axle to help out. Some systems can transfer power to the rear upon acceleration to improve traction. However, they revert to 2WD mode when coasting

Posted by: WRX DEMON Type R Mar 17 2005, 09:53 PM
This is a very informative thread. Good thing it's stickied.

Posted by: InitialN00b Mar 17 2005, 09:58 PM
QUOTE (Frost @ Mar 17 2005, 09:40 PM)

It's not semantics. It's downright misleading by the marketing people. If I sell you a V8 engine that only fires 4 of it's cylinders most of the time until it requires more power, is it really a plain old V8?

yes it is still a V8

does it have 8 cyls? yes
is it in a v config? yes

so it's a v8

dodge started doing that already; and NO ONE is B*tching wink2.gif

Posted by: WRX DEMON Type R Mar 17 2005, 10:03 PM
^ I wonder if thats available on the SRT-10. Should save a ton at the gas station, no?

Posted by: InitialN00b Mar 17 2005, 10:44 PM
I'm pretty sure as they develop the technology further, it'll be available in most V8 and V10 engines.

It's actually not that ground breaking. why it took them this long to develop, who knows.

Posted by: drifta_21 Mar 18 2005, 01:20 AM
All of you keep on forgetting on Quadtec!!!!! Anyways, thanks for the info.

Posted by: Frost Mar 18 2005, 03:15 AM
QUOTE (InitialN00b @ Mar 17 2005, 09:58 PM)
QUOTE (Frost @ Mar 17 2005, 09:40 PM)

It's not semantics. It's downright misleading by the marketing people. If I sell you a V8 engine that only fires 4 of it's cylinders most of the time until it requires more power, is it really a plain old V8?

yes it is still a V8

does it have 8 cyls? yes
is it in a v config? yes

so it's a v8

dodge started doing that already; and NO ONE is B*tching wink2.gif

Yeah but I said it is just a plain old v8? It's an ADVANCED v8. That's the point. AWD is a much more advanced system than classic 4WD ever was.

Frost

Posted by: sideways Mar 18 2005, 03:49 AM
I thought ur overdone v8 was how the attessa wasnt "awd" to you- when say to me it is.

Posted by: DGoReck Mar 18 2005, 05:08 AM
Here is a link to the Subaru Website.

http://www.subaru.com/allwheeldrive/ver2005/index.jsp
Click the 'What is the difference', and it will explain the differences between the 5 versions/aspects of AWD that subaru offers.

Posted by: WRX DEMON Type R Mar 18 2005, 06:13 AM
I've seen that site before - Hey Dgoreck, which one of those do our cars have?

I'm guessing continuous?

Posted by: Frost Mar 18 2005, 06:19 AM
QUOTE (sidewaysgts @ Mar 18 2005, 03:49 AM)
I thought ur overdone v8 was how the attessa wasnt "awd" to you- when say to me it is.

Again, I go back to the definition of AWD being ALL wheel drive. My understanding of this is that all wheels are powered all the time.

The Attessa system, as fancy as it is, is no different in its working idea than say Honda's full time 4WD system. Point is that it doesn't power all the wheels all the time.

I'm more against people who don't differentiate between 4WD (classic systems that involve you to manually switch to that mode) and AWD systems. The newer "on-the-fly" systems and full time 4WD systems are still fairly new ground to me (since I've never really driven one on true off road). My experiences lies with Toyota Landcruisers (pre 1994) on sand dunes and the Subaru Legacy GT (1997 and 2005) on snow and dry tarmac.

The v8 example was to highlight the clear differences between the original and the considerably newer v8's that are hitting up the market from Dodge. While, like InitialN00b said, they do have 8 cylinders in V orientation they are NOT classic v8's because they have evolved so much more than their original forefathers. Same thing with AWD and classic 4WD. Audi took 4WD and evolved it into a new breed of drivetrain so that you could have the advantages of 4WD (most of them) without the hindrances of 4WD.

In the essence, the chimp became a man.

Frost

Posted by: Nomake Wan Mar 19 2005, 08:10 AM
Now, what really throws a crazy wrench into the mix is what you would consider AWD. I have absolutely no idea how any 4WD/AWD systems work except those in Subarus. And merely in that category...

...there are older cars, like the XT6, which had what Subaru called "Push-Button AWD." By your definition, this is actually 4WD since it has to be activated. Then, you have the first-generation Subaru Legacy, which introduced AWD, ABS, the Boxer engine and a crapload of other ahead-of-its-time stuff. However, the AWD system in these first cars was not all that advanced. For instance, the system employed with the 4EAT (Automatic) sends 10% power to the rear and 90% power to the front. In essence, the car handled much like a FWD except in certain situations where the front tires slipped, in which case there was support power from the rear transaxle. The manual transmission sent a 50/50 split if I'm remembering my facts correctly. Therefore, what is the 4EAT's system, since it is essentially a power-assisted FWD?

The newer Subaru systems (as shown by DGoReck) are a hell of a lot more advanced, and as seen, are by your definition true AWD systems. It's still interesting that there's such a big difference between power distribution systems in manual and automatic Subarus.

Yeah, that's all I've got to really contribute. I always thought that the difference between 4WD and AWD was a mere marketing gimmick, but since there are systems where all of the wheels aren't powered all of the time, I think it's safe to use one of them to describe that system. That is... as long as everybody else on the planet knows what the hell you're talking about. ^_~

Posted by: VRr1FD Mar 20 2005, 08:16 PM
subaru - the beauty of 4 wheel drive. wink2.gif

Posted by: WRX DEMON Type R Mar 20 2005, 09:57 PM
Subaru - The all time leader (?) in All-Wheel-Drive.

Posted by: Frost Mar 20 2005, 10:18 PM
I'm not too sure of that.... lot's of people are doing AWD now and the father of the damned thing is Audi so Subby can't be the all time leader in it since Audi lead the way back in the late 80s.

Right now I'm dying to get my hands on the Acura's SH-AWD.

Frost

Posted by: Sti_Brumby Mar 20 2005, 11:27 PM
Cough leone Rx subaru 80 model is awd..

Posted by: InitialN00b Mar 20 2005, 11:37 PM
Audi had it since the early 80s

Well, the first to seriously put some thought into it at least.

Posted by: Frost Mar 21 2005, 02:02 PM
Ironically, the skeptics back then against Audi said AWD = 4WD and that it would never work in the rally scene. Someone bet on the wroooong side.

Frost

Posted by: WRX DEMON Type R Mar 21 2005, 04:32 PM
I agree with you guys on the Audi = father of awd thing.

I was confused that Subaru ad said "All Time leader in AWD".

Posted by: InitialN00b Mar 21 2005, 05:04 PM
QUOTE (Frost @ Mar 21 2005, 06:02 PM)
Ironically, the skeptics back then against Audi said AWD = 4WD and that it would never work in the rally scene. Someone bet on the wroooong side.

Frost

Indeed

It did take them a season to really develop it before they started mopping the floor with people's asses laugh.gif

Posted by: sideways Mar 21 2005, 05:11 PM
When awd first came out it didnt really make a huge denti n the rally scene- they performaed awesome but it was still developing, often theyd break before they could finish- it wasnt until technology caught up and they could make them lighter/stronger did you really see them pwning' the dirt

Posted by: Frost Mar 22 2005, 06:42 AM
Actually it did make a huge dent in the rally scene because they were just beginning to move from RWDs to FWDs. Audi came about and changed all that with the AWD idea. While granted it didn't sweep the standings in the first season due to technical problems (tell me what new technology never had startup problems), when it did finish, it finished way ahead of the competition and that was enough to shut up ALL the critics who suddenly began getting pink slips for not thinking outside the box.

Hence back to the AWD and 4WD arguement. 4WD is great and all but AWD is a whole new ball game.

Frost

Posted by: WRX DEMON Type R Mar 22 2005, 07:26 AM
QUOTE (Frost @ Mar 22 2005, 09:42 AM)
Hence back to the AWD and 4WD arguement. 4WD is great and all but AWD is a whole new ball game.

Frost

I like this sentence very much. happy.gif

Posted by: Sti_Brumby Apr 6 2005, 05:07 PM
All Wheel Drive (AWD): Most cars are front wheel drive, some are rear wheel drive.
That means that either the front or rear axle is powered and usually only one wheel.

All Wheel drive means that instead of either front or rear, both axles get power from the engine. This means that your Subaru is being pushed and pulled by all four wheel at the same time resulting in far superior traction in all driving conditions.

Subaru's all-wheel-drive is intended for everyday driving, detects any loss of traction and adjusts instantly in all situations including emergency braking, hard cornering, rain or snow slick roads with a substantial improvement in driver control and safety.
In other words... it's great.

Subaru All Wheel Drive (AWD). There are 3 systems- Continuous, Active and VTD


The types of all wheel drive used are:

Continuous AWD: Subaru manual transmissions use Continuous AWD, normally 50/50 front-to-back power split and use a mechanical viscous center differential to to vary the power split when there is a loss of traction.

Active AWD: Subaru's automatic transmission use Active AWD, mostly front wheel drive and uses traction sensing computer input to electronically vary the front to rear power split via a hydraulic multi-plate transfer clutch.

VTD AWD (variable torque distribution). New in 2001, VTD transfers powers front to back electronically. The power split is 45/55 front/rear and the rear wheel bias is designed for a more luxury car feel as opposed to the front bias of the Active AWD system. Usually 45/55 front to back split but that varies according to wheel slippage.

Personally i think subaru are the leaders in AWD systems They would have to be as every car they make now has it!

Posted by: AP1 Apr 12 2005, 01:10 PM
This explains everything, we have a 4WD Highlander and my Dad hasbeen asking me what 4WD is. All I know is that the power go to all 4 wheels. blink.gif

Posted by: Nd4SpdSe Apr 12 2005, 03:12 PM
I started to type stuff out, but i ended up doing some research, this explains it best:

4WD vs. AWD: Which is best for you?

Although the terminology is often used interchangeably, four-wheel drive (4WD) and all-wheel drive (AWD) are different types of systems with different pros and cons. The type of vehicle that's best for you depends on the conditions you typically face.

AWD continuously powers all four wheels and provides maximum traction in all driving conditions. It's especially helpful in wintry conditions and when driving in moderate off-road terrain. All AWD systems are full-time, so there's no need for a driver to manually shift into AWD mode. Its lightness and compactness makes AWD the system of choice for wagons, minivans, and an increasing number of SUVs, particularly car-based models.

The key difference between 4WD and AWD is that 4WD uses low-range gearing, which helps in challenging off-road conditions such as traversing rocks, steep slopes, or deep water. The vast majority of 4WD-vehicle owners, however, rarely need this capability. In addition, 4WD systems are typically heavier, which compromises fuel economy.

Most modern 4WD systems are full-time. But part-time systems are found on many pickups and traditional SUVs. These require the driver to manually shift between two- and four-wheel drive, and the vehicle can't be driven on dry pavement when in 4WD mode.


Posted by: Cubits Apr 12 2005, 09:36 PM
Why can't the vehicle be driven on dry pavement in 4wd mode? I drive my pajero on dry pavement in 4wd mode, but usually don't because of fuel economy and power loss issues. Maybe the can't would be better as shouldn't?

4wd can easily be single range (we call it single/dual range), but isn't common. Single range 4wd was only really seen on lightweight/car applications.

The key difference is AWD systems use torque sensing diff's to redistribute the torque to each wheel seperately, while 4wd systems have fixed torque distribution.

Posted by: sideways Apr 12 2005, 09:41 PM
I thought driving on the road with 4wd engaged was hard on the difs and would break em easy? what ive been told at least, never thought much about it

Posted by: Nd4SpdSe Apr 13 2005, 04:41 AM
This is why:

http://www.4x4abc.com/4WD101/axle-wind-up.html

Related article on why not:
http://www.4x4abc.com/4WD101/def_turnpart.html

Unless your Pajero's sytem is Full-Time 4WD
http://www.4x4abc.com/4WD101/def_turnfull.html

Posted by: Cubits Apr 13 2005, 05:20 AM
Aaah, it's actually both. The transfer case has 2wd and 4wd modes with a lockable central diff, so it can operate as 4wd on pavement fine, just not with the diff locked.

Posted by: AP1 Apr 13 2005, 05:43 AM
Wait, I don't get it, why can't it be driven on dry pavement when in 4WD?

Posted by: Cubits Apr 13 2005, 05:59 AM
Because in a turn the front wheels trace a wider arc than the rears, so the front wheels have to spin faster (more distance = more rotations).

Unfortunately, in 4wd's without a centre diff, the front and rear wheels are forced to spin the same speed, which means something has to give. In low grip conditions, it's usually the rear tyres that slip, but on a good grippy surface the drivetrain will fail first.

Posted by: Nd4SpdSe Apr 13 2005, 06:46 AM
QUOTE (Cubits @ Apr 13 2005, 05:20 AM)
Aaah, it's actually both. The transfer case has 2wd and 4wd modes with a lockable central diff, so it can operate as 4wd on pavement fine, just not with the diff locked.


Shouldn't make a difference if it's locked or not, a locked diff just prevents the tire with less traction to get all the power. Like rock climbers, sometimes they have1 or 2 wheels in the air, they use a locked diff so all tires move at the same time, otherwise the tire in teh air will get all the power, and they couldn't move. On a paved surface, since the tires can't slip, they have to move at the same time, and like you said, since the outter tire moves faster than the inner tire, and with (caution, double negative) no lack of traction, the diff will be strained and can pop or break.

Posted by: Cubits Apr 13 2005, 07:08 AM
I think you're confusing the front and rear diffs with the centre diff.

I can lock the centre diff to transfer torque evenly front/back, but the left/right transfer is still open (although the rear has a viscous lsd). If i put a front wheel in the air with the centre diff open the car won't move. Having it closed will force the rears to drive despite the front being airborne.

This is why top end offroaders have lockable front/rear diffs or run the more durable spool diffs, so you can rock-crawl and essentially drive with one wheel.

Posted by: LanEVOchris Apr 14 2005, 07:34 PM
4wd or four wheel drives are cars that run on 4 wheels. Unlike FF or FR or MR or RR, it has a faster pickup and more torque.But 4wd consumes a lot of petrol.
In Malaysia, most 4wd run on diesel and are equipped with turbo intercoolers.
Overall, 4wd are the best. Cars like Skyline, EVO, Impreza and H2 are fast because they are 4wds

Posted by: sideways Apr 14 2005, 08:04 PM
^--- rolleyes.gif

awd has the advantage off the line IF your making some good power, this is because 2wd cars will spin their tires easy and awd has more chances to have forward traction, after this- awd is dead weight. Awd CAN also have advantages with accelerating abilities on corner exit.

HOWEVER awd (and ff) have "limited lines". Basicly theyre going to understeer pretty good on exit, just think about traction circles and its clear why. This is a big reason why rwd vehicles do well in competitive head-head racing.

Lastly, whats his awd has "more torque" deal? Generaly speaking, awd drivetrains are much heaver and theres more for the power to go through; to be blunt awd has (Generaly) the highest drivetrain loss %, with Frs being next, and ff/mr/rr (transverse 2wd vehicle) being last.

Posted by: Cubits Apr 14 2005, 09:13 PM
Let's not forget that a good launch with a awd/4wd is quite a bit harder on the clutch. It is much easier to bog the car than with a rwd, and the chance of popping the clutch is high (i've seen soo many wrx's and skylines blow clutches!!).

Posted by: sideways Apr 15 2005, 01:32 AM
^-- word to that, thought about pointing it didnt feel like it. The extra drive train means you gotta rev the crap out of your engine to properly launch it (thus the killage of clutches), and its pretty easy to let it out too fast (stall) or not fast enough (slower launch, more clutch wear). Good awd cars need heavy clutches, not the easiest to have that "finese" on

Posted by: Sti_Brumby Apr 15 2005, 04:03 PM
Any clutch would wear out if you got good power goign through it....

Posted by: sideways Apr 15 2005, 05:04 PM
Not the point. The point lies in the difference of -how- your launching differently for speed.

Posted by: Frost Apr 16 2005, 10:19 AM
Again, I am surprised at how this thread still lives...

Pros:
RWD = Good for perfect traction (ie: dry and warm)
FWD = Good 2WD compromise for anything less than perfect traction
FWD = Best for bad traction (makes most of what little grip is available)

Cons:
RWD = Drivetrain loss, hard to work on compromised traction
FWD = Understeer due to front heavy
AWD = Most drivetrain loss, 4 wheels powered means twice as much wear and tear and twice as much power being siphoned from engine

Frost

Posted by: Sweeper May 26 2005, 05:32 AM
Now perhaps I will open something that hasn't been counted before.
But before I begin I want to define what I mean:
4WD, Permanent 4 wheel drive
AWD, Like the Skyline, 2 Wheel drive until traction loss.

What I want to bring in is modified AWD, lets take the very familiar Skyline ATTESA E-TS.
Now, we slam in an aftermarket controller that should allow you to set the AWD system to PERMANENTLY work in a 50 / 50 distrubution manually.
How would this go if we put it against normal 4WD?
Now of course I do assume he has the controller pre setup prior to traction loss.
But like the first post in this thread said, AWD is bad off-road, well how will the controlled AWD fare where it has permanent 4WD set by a controller?

I am not bringing any statements into this one at the moment as my car know how guy appearently has gone to bed (Aussie) so I cannot ask him for more specifics.
Generally it is allready summed up the weakness of AWD, the response time.

Well I posted this to bring a new AWD system into the discussion, the ones that uses a controller, modified ones.

Posted by: sideways May 26 2005, 12:23 PM
QUOTE
AWD, Like the Skyline, 2 Wheel drive until traction loss.


attesa is one of the onyl few to actualy do this, most constantly power all 4 wheels to some extent.

Posted by: WRX DEMON Type R May 26 2005, 05:18 PM
Subaru's newer AWD systems distribute power during accel and braking too.

Mine unfortunetly is 50:50 all the time. But same principle of when one wheel slips, the other 3 pick up the slack is there.

Posted by: sideways May 26 2005, 07:21 PM
50:50 all the time huh.gif u sure about that?

Posted by: WRX DEMON Type R May 26 2005, 07:30 PM
im very sure.

it's called continuous AWD.

If your wondering if my car is front wheel biased - it's not. That's only in the automatic models.

http://www.cars101.com/subaru_terms.html

Posted by: Subaru Jan 4 2006, 07:45 PM
QUOTE (2.5RS DEMON @ May 26 2005, 07:30 PM)
im very sure.

it's called continuous AWD.

If your wondering if my car is front wheel biased - it's not. That's only in the automatic models.

http://www.cars101.com/subaru_terms.html

Or Symmetrical AWD (spell?) happy.gif

Posted by: sideways Jan 4 2006, 10:50 PM
Check them dates wink2.gif

Posted by: EA99 Jan 4 2006, 10:53 PM
lawl hes new and a subaru driver so maybe it was OK for him to revive? wink2.gif which reminds me i thought 2.5RS was coming back?

Posted by: Subaru Jan 4 2006, 11:40 PM
Oh.. wasn't paying attention, !! ok sure this time I won't revive anything else

*promise*

crying2.gif

now I feel stupid..*knock heads on table*

Posted by: BOZZ Jan 5 2006, 09:04 AM
QUOTE (EA99 @ Today at 1:53 AM)
lawl hes new and a subaru driver so maybe it was OK for him to revive? wink2.gif which reminds me i thought 2.5RS was coming back?

Nope he's never coming back... He's too scared people will make a fool out of him if he does come back.... ><

Posted by: Frost Jan 5 2006, 09:29 AM
He did come back.

He posted in the "Check out my S13 and AE86" thread.

Frost

Posted by: kel Jan 5 2006, 10:30 AM
Not quite, look at the date

http://idforums.net/index.php?showtopic=10903&view=findpost&p=233599

However! his last active date on this board was the 21st of dec 2005

Posted by: Frost Jan 5 2006, 01:00 PM
Whoops.

I thought I saw January, 2006. Damn that thread is old. I thought it was a new thread!

Frost

Posted by: WRX DEMON Type R Jan 10 2006, 07:13 PM
Whoa...


Hey Kel!

How is your Mom's Civic doing? I wonder how much you spent repairing it... I cant remember, but it was a large sum, wasnt it?

Posted by: hellbent Jan 10 2006, 07:21 PM
Oh shit, he is back. laugh.gif

Heard u got a new 2.5RS. JUst remember now not to drive it in a flood
J/K.

U missed quite alot

Posted by: kel Jan 10 2006, 07:54 PM
QUOTE (2.5RS DEMON @ Today at 11:13 PM)
Whoa...


Hey Kel!

How is your Mom's Civic doing? I wonder how much you spent repairing it... I cant remember, but it was a large sum, wasnt it?

indeed it was ..but the leggy is comeing soon so whatever cool.gif

Posted by: WRX DEMON Type R Jan 10 2006, 07:55 PM
How R plans for the Legacy going?

Posted by: kel Jan 10 2006, 07:58 PM
looking at april now

a Q Whats your TSC name

Posted by: sideways Jan 10 2006, 08:31 PM
PMs tongue.gif

Posted by: WRX DEMON Type R Jan 10 2006, 08:31 PM
Anyone have a picture of the underside of a Skyline GTR?

I want to see what the driveline looks like. I wonder if it's anything like the Murano.

Posted by: hellbent Jan 10 2006, 08:47 PM
I might have some laying around. Being as I used to be the skyline nerd.

I can tell u with a diffent answer it is in no way compared to the Murano. Ive seen both and trust me, way different.


Posted by: WRX DEMON Type R Jan 10 2006, 08:51 PM
I'm sure well from over 5-15 years there would be some differences there but if you can find that pic it'd be helpful. I'm just curious.

I've been scouring all the image search engines for hours and cant find one decent picture of the complete underside.

A friend of mine keeps insisting that the Skyline's center differential is different from a center differential that you might find in an Audi or Subaru - in that it's not really a differential but a transfercase. I dont know any better so i want to verify if he's right or not as I've seen the underside of the Nissan Murano and Infiniti FX45 and there is a transfercase - but the driver has no control over when it's in 4wd or 2wd - just like a Skyline GTR.

BTW, dont the G35X, FX45 and Murano work on a safety oriented version of the ATTESA-ETS system?

Posted by: hellbent Jan 10 2006, 09:42 PM
Only the g35X and M35/45 have the ATTESA system. i dont believe the fx45 nor the murano has it. Of course the one on the m series may have the same name, but I believe the skyline system is far superior.

ur right about the no control on the skyline part. the system determines were is best to send the power. before a turn and turn-in, the power goes to the rear. coming out of corner, the system sends most of the power to the front.

let me get back to u, on the difference between the sooby, audi. gtr
since I havent studied on those 2 yet. so iam going to hold my answr until I do some research.

P.S.- I know i have some pics of the underside, just cant seem to find them.

Posted by: ams14 Jan 13 2006, 06:38 PM
LOL I remember when I had to explain the diff between AWD and 4WD to my friends,they taught they were both the same.

Posted by: sotti Feb 23 2006, 10:49 AM
this has probably been covered already, but I'll retierate it for fun.

AWD and 4WD ARE MARKETING TERMS

a car that claims to be AWD or 4WD will have 3 differentials and possibly a transfer case.

how many wheels drive power to the ground depens entirely on what kind of differentals you have.

several types of differentials are:
viscous coupling
clutch pack
torsen
helical
locking
locked
eleco/hyrdolic clutch pack
open
and more


You can have two wheel drive AWD as many subarus.
where the differentials are

O
|
V
|
O

open - visoucous - open so side to side only one wheel gets power but front to back both ends get power.

Or how bout a WRX (non STI)

O
|
V
|
V

So now both rear wheels always get power and one of the front wheels.


Then there is the STI:

H
|
EC
|
H

Where you've got helical LSDs front and back and electronic center diff. All four wheels all the time. hmm maybe subaru sould call it 2, 3, or 4 wheel drive.


Then audi does it like this
O
|
T
|
O

the torsen center send power front to back and the side to side torque transfer is handled by the ABS system.


Or there are 4WD trucks

LD
|
LG + xfer case
|
H

Where the front diff is locked all the time, and the rear diff is helical so it allows some slipping. So the center diff can be unlocked to drive only the rear wheels, or locked to drive both. And The transfer cas can put the transmission in low range multipling the torque.

Just about any type of diff can be setup to bias to one side. Some respond instantly to changing torque loads, some are reactive to wheel speed (so slippage has to occour first) and others are computer controlled. You can use any combinations of these to create a "perfect" AWD system.

Basically if it's got drive axels front and back you can call it AWD or 4WD!

THE MAGIC IS IN THE DIFFS

Posted by: JDMMA70 Jul 19 2006, 12:31 PM
ATESSA is actually Porsche not Nissan. The technology was first used on the Porsche 959, later Nissan adopted it to its Skyline GT-R

Posted by: sotti Jul 19 2006, 12:49 PM
QUOTE (JDMMA70 @ Today at 1:31 PM)
ATESSA is actually Porsche not Nissan. The technology was first used on the Porsche 959, later Nissan adopted it to its Skyline GT-R

Sorry, you are just wrong.

ATTESA is a nissan developed system. they may have talked to porsche about it, but the configuration is very different. Although it does share some simliarities with the porsches ability to shift power around it's not what's in the 959 at all.

Posted by: JDMMA70 Jul 19 2006, 01:18 PM
QUOTE (sotti @ Today at 1:49 PM)
Sorry, you are just wrong.

ATTESA is a nissan developed system. they may have talked to porsche about it, but the configuration is very different. Although it does share some simliarities with the porsches ability to shift power around it's not what's in the 959 at all.

from what I know it was just redesigned but the original concept belongs to Porsche

Posted by: Shirogane Dec 25 2006, 12:00 AM
I rather get a Montero rather than a CR-V since the AWD system is somehow dissatisfying, you pretty much know why.

P.S. i dont know if this is old or something.

Posted by: megamonkey@hotmail May 12 2007, 02:49 AM
wow, i don't know wat to think now, i'm just gona stick with and evo9 and beliving that it's magical

Posted by: HorizontalMitsubishi May 12 2007, 10:48 AM
i remember a few months ago i went up into the canyons with the pimp mobile (2001 qx4 fully loaded) and it was solid ice and there was a wrx wagon tring to make it up it was the funniest shit i have ever seen. one tire would spin, then another would spin and it was go around the car of tires spinning and stop then the car would move a foot or so and stop and do it all over again. i just cruised right buy him with the qx4 in 4wd mode. that car has 4wd mode and 1wd drive mode because it has a locker out back. i tried to drive it in 2wd mode and it would go anywhere. but i did do some cool awd donuts.

Posted by: Fujiwara Bunta-san May 20 2007, 06:04 PM
the post by BOZZ is of a great deal of technical competence... I will detail the Nissan ATTESA-ETS with Super-HICAS system and its performance dynamics as well as tuning dynamics later.... Zach (Takeshi) really loves those Skylines, be it GTS-t type M or full-blown GT-R , he doesn't care... and that's my real life friend, too... he told me that he loved Skylines way before I even knew what Inital D was... I have been interested in Japan since 1992, but I have only known about the mere existence (much less anything else) about Inital D since 2005.

I've been drifting quite well in real life for nine years now (half my lifespan so far) and my perspective on and in life has been totally and utterly changed ever since I bought the Live Action in '05... and for these reasons, I am justified in calling myself the "real Bunta..."

I prefer to let my actual driving do the talking rather than do something stupid like be arrogant or brag about something that does not have any substance.

I really really can drift... in the REAL world... and it's pretty cool for me personally... I know I'll be an Icon once I get over to Japan for the first time... hopefully in the next Twelve months. Twenty-four months absolute max...

Posted by: wangan_sti Jun 28 2007, 03:40 AM
This tread is getting intresting!!!

my impression of AWD is that its full time but send torque to diffrent wheels for traction
Also there are different types of awd like S-awd n DCCD

Posted by: Nomake Wan Jun 28 2007, 12:06 PM
QUOTE (wangan_sti @ Today at 4:40 AM)
my impression of AWD is that its full time but send torque to diffrent wheels for traction

Also there are different types of awd like S-awd n DCCD

You just contradicted yourself there. You got the first one wrong, and the second one right. There are different types of AWD: Correct. None of them are the same unless you're talking about the same model line from a particular company.

Whether or not it's 50/50 and sending torque to different wheels depends on the system. The one you're probably thinking of is the one in Subaru manual-transmission cars, which is 50/50 all the time but can send power left or right depending on the road surface (which is accomplished mechanically by use of limited-slip differentials). The STi 6-speed transmission with DCCD is the same, but allows changing of the torque ratio in the center differential to move power front or rear depending on the driver.

Then there's VTD-4WD in the automatic transmissions (1992-present in Japan, 2001-present in America), which is a 35/65 power split normally, but uses a limited-slip differential to send power forward depending on road situation, and uses a rear limited-slip differential to transfer power left or right depending on rear-wheel traction.

Plenty of systems, all of them work very differently... X-Drive, ATTESA, Full-Time AWD, VTD-4WD... list goes on and on and on and...

Posted by: atlantian Mar 20 2008, 04:52 PM
i think that the Subaru awd design FTW, symmetrical AWD is the way to go...

Posted by: DeeezNuuuts83 Mar 20 2008, 05:43 PM
Out of curiosity, what AWD cars have you driven?

Posted by: atlantian Mar 20 2008, 05:45 PM
my friend's S4, my mom's S60, and... that's it, but i do sim racing, and i think that i like the balanced, stable feel of the cars...

and i get suckered by subaru's advertising department...
http://www.youtube.com/watch?v=KKMBXFPeaz8
http://www.youtube.com/watch?v=RH5IIcbUDhM
the second one is my favorite car ad of all times

Posted by: DeeezNuuuts83 Mar 20 2008, 06:03 PM
So having driven an old S4 and an S60, what makes you jump to the conclusion that Subaru's AWD system is "the way to go" when you haven't driven it? Juuuuust curious.

Posted by: atlantian Mar 20 2008, 08:03 PM
as i said i am a sucker for their ad campaign... smile.gif

the impreza seems much better then the evo(no offense, it's a really fast car)
according to people i have asked, and symmetrical AWD is appealing because i hate torque steer... and another plus is... the short block flat 4... i love boxers... and i also love porsches(i HAVE driven a 911)... better then the gtr...(too many fan boys in this camp?)

Posted by: MattW Mar 20 2008, 08:13 PM
Symmetrical AWD just leads to understeer.

Posted by: DeeezNuuuts83 Mar 20 2008, 08:15 PM
QUOTE (atlantian @ Today at 9:03 PM)
the impreza seems much better then the evo(no offense, it's a really fast car)
according to people i have asked, and symmetrical AWD is appealing because i hate torque steer... and another plus is... the short block flat 4... i love boxers... and i also love porsches(i HAVE driven a 911)... better then the gtr...(too many fan boys in this camp?)

You just revealed that you really have no clue about what you're talking about. All theory, no practice.

Posted by: atlantian Mar 20 2008, 08:18 PM
i heard that subies don't like to turn much(top gear reviews), but, i don't really get how symmetrical AWD would be more so then any other AWD system...

i can always do what the rallists do... feint then neutral steer laugh.gif
jk, idk, i can always get into the habit of trail braking...
QUOTE
You just revealed that you really have no clue about what you're talking about. All theory, no practice.

yes, i have driven some(very little) cars, and i am relying on books and demo videos, and sim racing...

Posted by: WRX DEMON Type R Mar 20 2008, 08:36 PM
QUOTE (MattSAF1 @ Today at 11:13 PM)
Symmetrical AWD just leads to understeer.

Is this your own opinion?

Or did you quote someone who actually knows what they are talking about?

Posted by: DeeezNuuuts83 Mar 20 2008, 08:36 PM
QUOTE (atlantian @ Today at 9:18 PM)
i heard that subies don't like to turn much(top gear reviews), but, i don't really get how symmetrical AWD would be more so then any other AWD system...

i can always do what the rallists do... feint then neutral steer laugh.gif
jk, idk, i can always get into the habit of trail braking...

yes, i have driven some(very little) cars, and i am relying on books and demo videos, and sim racing...

Hmm... I'll say this with restraint since I'm not trying to shoot you down.

What you're doing is watching YouTube videos and reading reviews (not a bad thing), taking them for the absolute truth (somewhat of a bad thing) then regurgitating it as an opinion when in fact it's just paraphrasing of someone else's opinion rather than expressing your own based on practice rather than theory (bad thing).

You can watch all of the Top Gear videos to ever talk about Subarus and read every publication talking about their asymmetric AWD system, but none of that will ever compare to wringing an STI out on an open road... a curvy one. You can listen to each and every song recorded by your favorite music artist, but none of that will compare to actually seeing them live in concert. You can watch every adult flick ever made and memorize every nasty act and position, but it won't compare to actually getting down with a lady. Get what I'm saying?

Obviously you don't absolutely have to drive a car to form your own opinion on it, but an opinion based on experience AND knowledge gives you some credibility. But if you have an opinion solely based on someone else's and try to act like you know what you're talking about, then you are going to get shot down, which is what is happening all over your thread.

Posted by: atlantian Mar 20 2008, 08:42 PM
ah... okey, then i can only say... "i heard that imprezas are understeery"

but i did actually drive some awd, fr, ff(daily), and rr (drove mr once, but that was just a short sprint around the island...)

Posted by: MattW Mar 20 2008, 08:42 PM
QUOTE (WRX DEMON Type R @ Today at 12:36 AM)
Is this your own opinion?

Or did you quote someone who actually knows what they are talking about?

A 50-50 split in AWD leads to understeer, this is a known fact. Which is why the STi has a 35-65 f/r split, to help it rotate better through corners.

Posted by: atlantian Mar 20 2008, 08:45 PM
what?!?!, how is more front wheel power lead to understeer... you must be bad at driving front wheeler because i drive an FF and never experienced understeer unless you try to romp on the throttle at the apex...

Posted by: DeeezNuuuts83 Mar 20 2008, 08:46 PM
QUOTE (atlantian @ Today at 9:42 PM)
but i did actually drive some awd, fr, ff(daily), and rr (drove mr once, but that was just a short sprint around the island...)

Yes, but not all of those were performance applications, which can have drastic differences in handling dynamics compared to non-performance applications.

Posted by: atlantian Mar 20 2008, 08:56 PM
QUOTE (DeeezNuuuts83 @ Today at 8:46 PM)
Yes, but not all of those were performance applications, which can have drastic differences in handling dynamics compared to non-performance applications.

hmmm, i just thought that you can generalize/categorize cars by their drive type...

FR-IS250(the new one with semi auto, performance), c240(my bro's baby... dry.gif , performance)
FF-ES300(my daily),'87 toyota celica(piece of crap i picked up for 100)
AWD-S4(performance), S60
MR-SW20(supercar)
RR-'74 911(supercar)

Posted by: DeeezNuuuts83 Mar 20 2008, 09:00 PM
QUOTE (atlantian @ Today at 9:56 PM)
hmmm, i just thought that you can generalize/categorize cars by their drive type...

FR-IS250(the new one with semi auto, performance), c240(my bro's baby... dry.gif , performance)
FF-ES300(my daily),'87 toyota celica(piece of crap i picked up for 100)
AWD-S4(performance), S60
MR-SW20(supercar)
RR-'74 911(supercar)

Sorry, but your classifications are WAY off. IS250 is not performance, C240 is not performance, and the SW20 and '74 911 are both definitely NOT supercars... far from it.

Not to be a jerk, but seriously, you need to stop posting, or at least do A LOT of research before you do. YouTube videos don't count.

Posted by: Frost Mar 20 2008, 09:21 PM
QUOTE (atlantian @ Today at 8:45 PM)
what?!?!, how is more front wheel power lead to understeer... you must be bad at driving front wheeler because i drive an FF and never experienced understeer unless you try to romp on the throttle at the apex...

I used to run autocrosses with a 2000 Corolla. It's as classical FWD / FF as it can get and it had MAD understeer when pushed hard on severe cornering so I have no clue wtf are you talking about when you say what you just said. Of course, there is always the option you weren't gunning it like I was on corners and I was REALLY gunning it (people said my tires were rolling over haaaard - even though I had enough pressure to barely maintain a solid contact patch).

My old AW11 had some slight understeer on heavy gassing on corners too but had good lift-off oversteer to compensate.

While I like the IS'es, I have to agree with Deez saying the IS250 is far from performance. It definitely is a sporty vehicle but far from performance. Even Lexus call's it just a "sport compact" car which can technically encompass anything with four doors nowadays and "sport suspension".

IS350, okay, now we're getting closer to performance. IS-F? Definitely.

IS250? The cheap entry car into Lexus lineup.

Posted by: WRX DEMON Type R Mar 20 2008, 10:12 PM
QUOTE (MattSAF1 @ Yesterday at 11:42 PM)
A 50-50 split in AWD leads to understeer, this is a known fact. Which is why the STi has a 35-65 f/r split, to help it rotate better through corners.

50:50 split... LOL, that's not symmetrical awd... Thats just equal torque distribution to the front and rear...

I thought you were saying something about Subarus in general - as you know, their logo is, "Symmetrical All Wheel Drive" (Referring to how both sides of the car; left half and right half - not front and rear - are symmetrical, or rather, somewhat symmetrical).

Posted by: atlantian Mar 21 2008, 08:13 AM
so... you guys agree the 911 and the mr2 is performance right?

and @ Frost... dry.gif
i am careful with the throttle... i don't get why you have to drive like a mad man to drive fast, i thoght it was "the less you do with the controls, the faster you go"(exact quote from my instructor)

Posted by: kos Jul 21 2008, 10:29 AM
911 yes, mr2 no.

look at the 2000+ mr-s'....those arent geared really towards performance at all

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