4 wheel drive VS. AWD

[RSdriftPrncss]

Hey everyone my Dad, boyfriend and I are having a discussion about what the differences are between 4 Wheel Drive VS. AWD. Please help me help them (me too) understand what it is and what it does. :lol: Also if driving a AWD over a mountain pass into CO should you put chains on you car?

[lminette]

Regarding AWD over a mountain pass it all depends on the amount of snow and your tires. If you have a decent set of all-seasons (Kumho Ecsta ASX's) you should be fine in light to moderates snow. I would carry chains just in case, but you should be fine.

[MetalNeverDies]

if you have the same tires on an awd subaru as a 4wd vehicle with out lockers would you be able to go just as far the 4wd with the awd

[RSdriftPrncss]

He bought new tires today (All Seasonal).

[lminette]

You should do fine!! The Subaru AWD system is well proven and very capable. The only issue may be ground clearance if you are comparing to a pick up.

[anaonbd]

but what's the difference between awd and 4x4? I would assume that both have dual gear boxes (front and rear) and maybe limited slip gearboxes too.

[lminette]

Check out this link from Subaru.com

http://www.subaru.com/sub/misc/coretech/index.html?from=topNav

[bfrancis827]

From what I understand:

4WD
In 4WD vehicles, power is only going to 2 wheels(1 front/1 rear) at any one point unless you have a LSD or lockers. The wheel with the least amount of traction gets the power. I was driving my dads Chevy and I got stuck on some ice even though only one wheel was actually on the ice(it was 2WD, but the front works the same as the rear on 4WD). Newer 4WD's have sensors that transfer power to the wheels that have traction.

AWD
In AWD vehicles, the power is delivered to all the wheels.

[JacksonRally]

The main major difference is in 4wd you have a transfer case, and in awd you have a center differential. With a transfer case you have to put it into "4wd" and an awd car/suv is always sending power to the front and rear differentials.

[lminette]

Nice simple explanation Kyle!!

[Drew84]

Yeah I always tell people 4wd can be selected from 2wd mode where Awd is constant.

[WRR]

Kyle is exactly right -

you can usually tell immediately by seeing if there is a lever or a switch to go in & out of 4WD.. that would be a 4WD or as in some of the later model SUVs, automatically become 4WD after the main drive wheels lose traction (like say a Honda CRV - what Honda calls 'Real Time 4WD' - which is FWD until the front wheels start spinning then the rear wheels kick in)

AWD is always all-wheel-drive and normally has no transfer case & no high/low mode although some have center diff. locks which allows you to lock the front and rear power distribution at 50/50.

some vehicles kinda have a blend of both like some Jeep Grand Cherokees are all-wheel-drive but really use more of a 4WD design to move the power around.. some also have some pretty sophisicated stuff going on where the vehicle can determine which wheel has the MOST traction and send the majority of the torque to that wheel only -

bottom line - 4WD or AWD will not get you through everything even though many people believe it will - you still need good rubber and common sense (easy on the gas, the brake and the steering wheel) and normally, if you need chains on an AWD vehicle then you should put them on all four wheels so you don't overheat the center diff by spinning the rear wheels while the ffont tires have traction (chains) but this is a widely debated theory... check your owners manual or your local Subaru expert - I'm in SoCal and we need to put on chains if snow is even in the forecast so I don't consider myself an expert at all - & I grew up in Vermont with 3 feet of snow and we didn't own chains there... so there you go

[sleepyfu]

get some real snow tires (factory spied stud-LESS) and forget about chains. All seasons are 4 seasons, but in my book there is th 5th season - the snow/ice season (as I drive to the mtn 3 times a week).
CO 's snow is very dry, so I really don't see you needing any chains. chains are great when there is very deep unpacked wet snow w/ mashed potatos consistency.
ummmm, mashed potatos.... i am hungry.....
oh and main difference on 4wd ans awd is that 4wd when engaged, the front 2 will always have power to them, where as a good awd will transfer more power to the ones that has traction. 4wd has no front diff. either. so when turning on surfaces with traction they lock early.
________
360 (http://www.ferrari-wiki.com/wiki/Ferrari_360)

[UP2MTNS]

The main major difference is in 4wd you have a transfer case, and in awd you have a center differential. With a transfer case you have to put it into "4wd" and an awd car/suv is always sending power to the front and rear differentials.


and typically the gearing and power ratios are going to be very different, right?

I mean, put tow cable between an STI (locked rear diff) vs a Jeep Wranger in 4x4....not only will the wrangler pull the sti away pretty easily, but the sti is going to destroy itself trying to fight back.

yes/no? I don't know the answer, but I sure wish someone would put this little experiment together, it would be fun to watch!

[rllyrckt]

WELL I GOT THE JEEP WRANGLER PART OF THE EXPERIMENT, WHO WANTS TO BRING THE STi.....no i couldnt do that...but maybe if it was a new STi i could.

[WRR]

get some real snow tires and forget about chains yes, except some states, like Cali .. make you run chains if there is enough snow... maybe I should say if the CHP thinks there is enough snow.



and main difference on 4wd ans awd is that 4wd when engaged, the front 2 will always have power to them, where as a good awd will transfer more power to the ones that has traction. 4wd has no front diff. either. so when turning on surfaces with traction they lock early.

4WD does have a front diff.. look under the front of any 4WD truck

and I'm not so sure on the AWD power distribution but I think my WRX is something like 70F/30R normally and pushes badly in loose stuff (understeer, where the front just want to keep going straight) so I don't think it would ever send that much torque to the rear wheels but I have not been stuck yet so I can't say for sure...

& that mashed potato stuff is super slippery!!

[pwlucas]

AWD refers to a four-wheel drive system that does not use a conventional transfer case. Instead of the transfer case controlling the front wheels(like in 4x4) the transfer case controls the rear wheels(like in an evo or dsm). Thats basically the difference but all systems are different in ways.

[sleepyfu]

4x4 and awd are not required to put chains on here in WA :)

I stand corrected. transfer case is what cuz the crappy turning on dry surface on 4x4
The transfer case on a part-time four-wheel-drive system locks the front-axle driveshaft to the rear-axle driveshaft, so the wheels are forced to spin at the same speed. This requires that the tires slip when the car goes around a turn. Part-time systems like this should only be used in low -traction situations in which it is relatively easy for the tires to slip. On dry concrete, it is not easy for the tires to slip, so the four-wheel drive should be disengaged in order to avoid jerky turns and extra wear on the tires and drivetrain.

http://auto.howstuffworks.com/four-wheel-drive.htm
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[wolfman79]

In Colorado any passenger vehicle that is equipped with proper snow tires is not required to have tire chains. The tires they are talking about are any snow tire with the Mountain/Snowflake symbol. Chains are only considered a traction enhancement device as are the aforementioned tires. On a personal note though I run snow tires from November through April(plus on stand by for rest of year)and I still keep a set of cables/chains in the back of the car for precationary reasons.

As for my take on the 4wd vs AWD; if you don't have either Limited slip or Locking diffs then it really doesn't matter. AWD in a Subaru is pretty much automatic, you just drive and the car handles where to put the power for you, with good tires and driving within your limits(unless you are one of the few who can actually push the car beyond its limits)you won't have many problems regardless of conditions. Most 4WD systems rely on a transfer case that requires driver interaction. It is up to the driver to determine when to engage 4wd and also what range assuming a hi/lo t-case. For the vast majority of situations where it is fair to compare an awd car to a 4wd truck i.e. on almost any public road/highway, an awd system is normally the better option.

But regardless of awd or 4wd it is your tires that have the biggest impact on how well your car handles inclement conditions. Awd/4wd gets you going but your tires are what enable you to go and turn and stop. That is why chains are only recommended for the front wheels; they are what turn the car and also handle ~70% of the braking.

[rollo]

It's marketing - probably originated by either Audi or Subaru. In the US, 4WD cars are referred to as AWD and trucks are 4WD. In the UK for instance, anything with all four wheels driven is referred to as 4WD or sometimes 4x4 (e.g. VW Golf R32, Evo, Panda 4x4, Sierra XR4x4). Subarus are the exception, since they trade on the "Symmetrical AWD" thing.

Of course what this has meant is that here in the US, people assign characteristics to one or the other and get into long drawn-out discussions. The reason that "4WD" typically has hi-lo, selectable 2 or 4 or whatever is that trucks have that stuff. "AWD" doesn't because cars don't. But if you could select low gear and 2WD in an STI, would it become "4WD"? Seems unlikely.

You want proof it's marketing?
2008 Honda CR-V 4WD LX (http://automobiles.honda.com/cr-v/price.aspx?Model=RE4838EW)
If you can find me the t-case controls on a CR-V then I will be convinced otherwise :D

Basically, it has come to be that 4WD sounds 'rugged' and AWD sounds 'sporty'.

[lminette]

Well put Phil as always!!!

[UP2MTNS]

It's marketing - probably originated by either Audi or Subaru. In the US, 4WD cars are referred to as AWD and trucks are 4WD. In the UK for instance, anything with all four wheels driven is referred to as 4WD or sometimes 4x4 (e.g. VW Golf R32, Evo, Panda 4x4, Sierra XR4x4). Subarus are the exception, since they trade on the "Symmetrical AWD" thing.

Of course what this has meant is that here in the US, people assign characteristics to one or the other and get into long drawn-out discussions. The reason that "4WD" typically has hi-lo, selectable 2 or 4 or whatever is that trucks have that stuff. "AWD" doesn't because cars don't. But if you could select low gear and 2WD in an STI, would it become "4WD"? Seems unlikely.

You want proof it's marketing?
2008 Honda CR-V 4WD LX (http://automobiles.honda.com/cr-v/price.aspx?Model=RE4838EW)
If you can find me the t-case controls on a CR-V then I will be convinced otherwise :D

Basically, it has come to be that 4WD sounds 'rugged' and AWD sounds 'sporty'.

I would agree with you on the 'CRV' and modern SUV's. My buddy has a volvo SUV with 'real time' AWD and well, he got stuck on an icy mountain access road OUT of a ski resort, and it was just a slight incline. It was embarrassing as suby after suby went flying by us. (since then, I've never let anyone else drive me anywhere in a winter driving situation, haha)

anyway...where I disagree is with REAL 4x4's....its not just the transfer case, its a direct drive (none of this open/LSD stuff), where you're always putting power to all 4 wheels, no matter what, even if one is in the air. (refer to the earlier post about tire excessive wear with 4x4's on corners, etc).

That's real 4x4 action and well, yeah...unfortunately most of today's suv's are nothing like that.

[WRR]

If you can find me the t-case controls on a CR-V then I will be convinced otherwise

I am going to disagree Phil (if for no other reason then to just keep the thread going :p)

the Honda CRV is a FWD vehicle that becomes 4WD automatically once the wheel mounted speed sensors tell the ECU that the front wheels are spinning thus an 'automatic lever' but never-the-less it is, for all practical purposes, a 2WD most of the time.. my Subaru is AWD all the time, always sending power to all four wheels -

and yes Jon - back in the day the Dodge PowerWagon and the International Scout are the two that come to mind... way back like 60s.. were tru 4WD with all four wheels being supplied power once everything was locked in... they would go anywhere!! a friend of mine has a Range Rover with front, rear and center diff locks so he can lock all four wheels together and it could probably go anywhere as well except it has never even been dusty :(

[UP2MTNS]

just got to thinking, maybe this thread should actually be 4WD vs AWD vs 4x4, where 4WD<AWD<4x4 :D

[wr-ecks]

ha ha funny argument

[BlackParis]

No comments on the 4wd/awd/4x4 things...

as far as going over a mountain pass, it may be a good idea to carry a set of chains with you should you need them, also remember going up wont be as hard as coming back down, make sure you disable your abs, cause if a snowy hill gets too steep the abs will work and actually speed the car up (potentially bad) where as if you lock up your tires you will slide, but prolly stop LONG before the ABS would let you ;)

[BorkedWRX]

No comments on the 4wd/awd/4x4 things...

as if you lock up your tires you will slide, but prolly stop LONG before the ABS would let you ;)

Just make sure not to slide off a cliff ;)

[IneedRS]

lol symmetrical awd is so much better than everything else!

[98obster]

Subarus do great on Colorado mountain highways in the wintertime. But make sure you have newer all seasons or even better, a dedicated winter setup.

Subarus are not 4wd because the front and rear differentials are open (or the rear is Limited slip). If we could lock the differentials then we could crawl on one wheel. Subarus ability to tranfer power back and forth from the front to the rear is superior to most awd systems out there when all 4 wheels have traction. "From the wheels that slip to the wheels that grip" is true for the most part-you just may not have enough power getting to the gripping wheel to move if it is the only one. So, you may not be rock crawling in your subie but you won't lose your rear end turning left in a snowy intersection-unless you want to ;). Have a safe holiday and New Years. jon

[rollo]

I am going to disagree Phil (if for no other reason then to just keep the thread going :p)

the Honda CRV is a FWD vehicle that becomes 4WD automatically once the wheel mounted speed sensors tell the ECU that the front wheels are spinning thus an 'automatic lever' but never-the-less it is, for all practical purposes, a 2WD most of the time.. my Subaru is AWD all the time, always sending power to all four wheels -


So the Honda system works like the VW Synchro system.. which was marketed as AWD... cos it was fitted in cars. The 4Motion is a similar deal I believe.

As for 4x4.. 6x6 ftw :D
cX55UAUtYhs
Ah Pinzgauers.

On a tangent, have you guys seen the new GTR's drivetrain? Two driveshafts?!

[Blix666]

^ i'd rally it

[BlackParis]

^ too tall.. make a 6x6 suby ;)

[noisycricket]

Hey everyone my Dad, boyfriend and I are having a discussion about what the differences are between 4 Wheel Drive VS. AWD. Please help me help them (me too) understand what it is and what it does. :lol:

It's about the same as the difference between Positraction and Traction-Lok and Sure-Grip.

Basically it's whatever term the marketing department feels like putting on the car!

I think it was Audi that invented the term "All Wheel Drive" to differentiate their cars from trucks.

Normally the difference is, 4WD = part time and no center diff, AWD = full time and is designed for driving on-road.

But then all those AMC Eagles were called "4WD" and were full time... lots of trucks in the 60's and 70's were full time with no 2wd option... lots of EA82T powered Subarus were full time 4WD, not AWD. Sure they had a lockable center diff but so did the Audis... and all the 4WD modern Jeeps that are full-time... and the 4WD other trucks that are full time... and "AWD" minivans and cute-utes that really are FWD until the front tires slip and then and only then do the rear tires start to see torque...

So it's marketing!

Also if driving a AWD over a mountain pass into CO should you put chains on you car?

You still need to slow down on the other side, and have four wheel brakes, right?

[Rallycat66]

It's all marketing hype...

But here's a good explanation of the various systems manufacturer's use for "AWD" cars.

http://www.autozine.org/technical_school/traction/tech_traction_4wd_2.htm

What is not discussed here is transfer cases (i.e. traditional 4X4 trucks) in which you are engaging the transfer case and effectively locking the front and rear drive shafts together.

Tim

[rollo]

Alright Jack.. now you're disagreeing with me, NC and Tim.. you wanna swap sides?

:lol2:

[wolfman79]

No comments on the 4wd/awd/4x4 things...

make sure you disable your abs, cause if a snowy hill gets too steep the abs will work and actually speed the car up (potentially bad) where as if you lock up your tires you will slide, but prolly stop LONG before the ABS would let you ;)

So very true. I've had one drive down I-70 when I literally had to drive opposite of what seemed logical. Every time I hit the brakes the car would start to speed up, take foot of brakes and it would slow down. this was all at slow speeds ie < 10 mph during on of worst snow storms to hit CO in many many years.

[BorkedWRX]

Oh on the driving down hill part... I almost forgot...

If you need to stop and get out of the car while pointing downhill, don't completely rely on the e-brake to hold the car there, remember e-brake = brakes in the rear only, your car will start to slide down the hill as there is no weight on the rear...

I know from experience. That is all.

[WRR]

Alright Jack.. now you're disagreeing with me, NC and Tim.. you wanna swap sides?

:lol2:


good discussion but....



I'm not switching sides... maybe the marketing has me brainwashed but I still believe that if 'all wheels don't have the opportunity to get power all the time then you don't have all-wheel-drive'..

Dodge truck = 4WD (manully activated low or high 4wd but normally 2wd)
Honda CRV = 4WD (automatically activated 4wd but normally 2wd)
some Jeep Grand Cherokees = AWD and some Jeep Grand Cherokees = 4WD depending on drivetrain (again the 2WD versions have a manually activated transfer lever but the AWD versions are all wheel drive all the time)
Subaru = AWD (cause thats what it says on the center of my my back window :mrgreen:) but some of the old skool orig. Subarus had a manual lever which means they were 4WD

VW/Audi/etc, etc - I don't know - they are probably lying for marketing reasons :tongue:

[noisycricket]

Yeah but you could leave the Subarus in 4wd mode. I drove mine in 4WD almost exclusively. It didn't hurt anything except for binding up a lot when trying to make really tight corners. But the owner's manual didn't say it was a bad idea, just that you can expect to feel a binding sensation.

Besides, the car had no effective rear brakes, so if it was anything but clear and dry, you needed it in 4WD to keep the fronts from locking up. The first two months I had it, it had blown brake lines, so I used the handbrake to stop. (Handbrake on the front calipers) Worked just fine :)

It was really nice though because I could scientifically find the right tire pressure balance front to rear. Just had to shift into and out of 4WD while on the highway, and adjust pressures until ikt shifted smoothly. I think I settled on 44/35. My experiences with a 2WD mountain bike made me really hate transmission bind so I was careful to get things right. Fuel economy with that car was really good, almost as good as my less aerodynamic but two wheel drive Golf gets.

[rollo]

I'm not switching sides... maybe the marketing has me brainwashed but I still believe that if 'all wheels don't have the opportunity to get power all the time then you don't have all-wheel-drive'..

Interesting.. so AWD = "permanent 4WD" (IYO) :D ?


Dodge truck = 4WD (manully activated low or high 4wd but normally 2wd)
Honda CRV = 4WD (automatically activated 4wd but normally 2wd)
some Jeep Grand Cherokees = AWD and some Jeep Grand Cherokees = 4WD depending on drivetrain (again the 2WD versions have a manually activated transfer lever but the AWD versions are all wheel drive all the time)
Subaru = AWD (cause thats what it says on the center of my my back window :mrgreen:) but some of the old skool orig. Subarus had a manual lever which means they were 4WD

VW/Audi/etc, etc - I don't know - they are probably lying for marketing reasons :tongue:

Hmmm... doesn't all that mean that there is no definition and that it's down to the marketing to decide which term is appropriate?

Ah well. See.. I did say that the question always spurred much discussion.

[RS-ti_Andy]

and typically the gearing and power ratios are going to be very different, right?

I mean, put tow cable between an STI (locked rear diff) vs a Jeep Wranger in 4x4....not only will the wrangler pull the sti away pretty easily, but the sti is going to destroy itself trying to fight back.

yes/no? I don't know the answer, but I sure wish someone would put this little experiment together, it would be fun to watch!


note that my jeep had 275 lbs torque out of a inline 6... Buttt, my jeep wieghed 200 lbs less than a sti.. if i had my jeep id volenteer it right now! haha

[noisycricket]

note that my jeep had 275 lbs torque out of a inline 6...

What did you have in there, a Ford 300 or something?

[409industries]

UNIMOG FTW!

nw2D6RtrGKE

The red one with the white strip is so sweet!

I agree that a true 4x4 system should be essentially all wheels turning regardless of who is slipping or not (front / center / rear diffs locked). Since AWD has a series of open and limited slip diffs, often with a computer controlling everything... it does play to the marketing side of things a bit.. perhaps not as "rugged" as a truck, etc.

AWD is a great tool on our subaru's but can be easily defeated by a lack of planning or an overconfident driver. Be sure you have good rubber on those wheels when traveling into snow and ice, give yourself lots of space around other cars and just take it easy.

Its not hard to spin a Subaru in the snow if you're driving like an idiot!

[wolfman79]

Yeah those are definitely more rugged than my subie ever could be. That's a pretty neat vid. Wonder where people find some of those things.

[RS-ti_Andy]

see if awd cars were true... then we would be breaking sh*t all the time turning going slow.. and well turning in general.. like my jeep, engage it into 4X4 and if you arent on slippery ground it is not wise to drive in it.. even told me that on my cealing lol

[RS-ti_Andy]

What did you have in there, a Ford 300 or something?


i would never ever rock a ford motor over a 4.0L inline 6 from Jeep! the motors are tanks!

[RckyMtnLegacy]

Yeah I always tell people 4wd can be selected from 2wd mode where Awd is constant.

What about 4wd all the time. I cant select it it just always there.