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why AWD?


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13 replies to this topic

#1 p3pppx

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Posted 09 December 2003 - 10:22 PM

Just saw this Nissan commerical awd when you need it:

picture of all cars using tire chains on a sunny day

in other words full time awd is overkill!?

What are the benefits of "full time" AWD? Of course I've read everything on subaru site about AWD and know its good for adverse terrain (snow, offroad), exceleration (w/ 5mt outback not much advantage) what else?

#2 alias20035

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Posted 09 December 2003 - 11:18 PM

Originally posted by p3pppx
Just saw this Nissan commerical awd when you need it:

picture of all cars using tire chains on a sunny day

in other words full time awd is overkill!?

What are the benefits of "full time" AWD? Of course I've read everything on subaru site about AWD and know its good for adverse terrain (snow, offroad), exceleration (w/ 5mt outback not much advantage) what else?



Rather odd of Nissan, considering their new Pathfinder and Pathfinder Armada are full time 4WD (they even go so far as to call it AWD in some literature). They are also developing an AWD Infinity G35. And what about their fabulous Skyline GTR which is AWD (and not available outside of Japan:boohoo:).

Given that I am from Canada and drive between 5 and 8 months on snow and ice covered roads, I find AWD to be a very nice thing to have, and in some cases it is absolutely essential.

I find that the biggest benefit of AWD is the predictability that it affords in low traction situations, while its downside is causing the driver to be overconfident leading him/her to drive at a higher and often dangerous speed. AWD will not help braking, nor will it provide any safety advantage to the average driver above 30 MPH or so. The average driver lacks the skill to recover from a skid or perform an emergency manouever above 30MPH regardless of having AWD or not, I have taken several advanced driving courses, and even knowing the proper technique I still have trouble above 30mph. In some cases AWD can make a bad situation worse, since it can cause understeer due to the interlocked axles causing many emergency driving techniques to be less effective. Not generally an issue below 30MPH though, unless on ice.

Since I usually need AWD in low speed "snowplowing" or climbing an icy or hardpack snow hill, I find it to be a great asset. Since I do have the 5MT I find that I can better control the car in slippery conditions using engine braking, if the car begins to swerve I just tap the throttle to pull it straight. I also have four wheel drift and powerslide turns mastered.

#3 adge_082

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Posted 09 December 2003 - 11:40 PM

driving through large puddles of water at speed, awd will more or less drive straight through, you dont get that 'pull' on your steering wheel that you will experiance in a RWD vehicle, im sure this can only mean that its much safer to drive in the wet in an AWD vehicle.

If you were forced to leave the road at speed and stick a couple of wheels in the dirt beside the road awd will definately be an advantage.

#4 DerFahrer

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Posted 10 December 2003 - 12:14 AM

Let me summarize what Alias is saying: There is not one traction control or braking assist or any other contraption in the whole world that will save you if you do something stupid. These systems are to help you use the laws of physics to your advantage, not defy them altogether...

I know, I've done something stupid in my AWD Legacy before. I will admit to this even though I'm still embarrassed by it. I was pissed about something and proceeded to take a left-hand turn in the rain. For some reason, I decided to stomp on the gas before I was heading straight, because I had the same thought: I have AWD, I'm invincible! :brolleye: My rear end came out, and I countersteered too much, flew back the other direction and slid sideways and scuffed my bumper across a parked car.... Did little more than remove some of my paint, but I screwed the parked car up pretty bad.

The policeman was happy that I stayed and waited, and as I described what happened, he actually complimented me for not doing MORE damage! So he simply allowed the information exchange and let me off without a ticket.

But I still mentally kick my own rump roast for doing something so stupid and for making my already-horrible day even worse. Plus spending $300 for a new bumper and getting it painted.

Yet it was a valuable lesson for me. I have more caution in the rain now, and I simply have a better understanding of the dynamics of handling an automobile. I am a better driver for it.

#5 nickb21

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Posted 10 December 2003 - 12:40 AM

Yea, I saw that commercial the other day, wasn't quite sure what to make of it. I wonder how the their system works, if its 2wd unless it senses a traction issue, which means it then has to engage the other axel, or is it some kind or 90/10 split.

I can see some degree of fuel savings by using a 2wd configuration, but can it really be that much..

Alias made a pretty good comment in one of his other posts:

Subaru's AWD system is "precautionary" while most of the others are "reactionary".



Would you rather have a system that's "always on" and ready, or one that'll have to kick in and figure out what it needs to do... just my thoughts.

#6 LegacyT

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Posted 10 December 2003 - 06:23 AM

People saw AWD drinks gas I say thats complete untrue. my Legacy(not my turbo but N/A) beats my friends accord in fuel consumption

#7 kevinsUBARU

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Posted 10 December 2003 - 07:51 AM

sounds like the Pathfinder has a similiar system like Jeeps Quadratrak or however it is you spell it. It works well, but it noticeably slips before it engages. It is definately not as seamless as Subaru AWD.

#8 Setright

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Posted 10 December 2003 - 07:53 AM

Okay, here's my "humble" opinion:

No car should be without full time 4WD. Please note that I use the term broadly, and do not intend to discuss terminology, ie. 4WD vs. AWD.
All four wheels carry the car, brake the car, steer the car (the rear wheels provide the fulcrum, don't forget), it follows that all should be allowed to propel the car too.

In terms of on-the-limit handling, I find that 4WD has much more predictable behaviour and a wider range of possiblities. Granted, this may not be relevant to all people.

HOWEVER, all people will need to join a main road from a side road, often into a stream of fast moving traffic, and possibly in wet weather. Maybe even icy if you are really lucky. Here 4WD is an unparalled advantage.

No amount of "traction control" on a 2WD vehicle can utilize the grip available from four tyres.

There are a number of other similar occurences where a quick burst of acceleration can help smooth traffic flow, or avoid a dangerous situation. Times when tedious wheelspin would just get in the way!

#9 MilesFox

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Posted 10 December 2003 - 01:52 PM

Originally posted by alias20035
The average driver lacks the skill to recover from a skid or perform an emergency manouever above 30MPH regardless of having AWD or not, I have taken several advanced driving courses, and even knowing the proper technique I still have trouble above 30mph.

Since I usually need AWD in low speed "snowplowing" or climbing an icy or hardpack snow hill, I find it to be a great asset. Since I do have the 5MT I find that I can better control the car in slippery conditions using engine braking, if the car begins to swerve I just tap the throttle to pull it straight. I also have four wheel drift and powerslide turns mastered.




some think you have to have a rwd to have fun. the average driver cant do a powerslide or drift effectively

the average driver doesnt know that you can do drifts and powerslides in a front-drive car either

#10 Setright

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Posted 10 December 2003 - 02:54 PM

Well, Miles, you cannot hang the rear end out by spinning the rear wheels on a FWD - and that's what I call a powerslide.

BUT, you certainly can get the back sliding by other means...lift-off, handbrake, trail-braking into a bend you have entered too fast anyway...

#11 NoahDL88

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Posted 11 December 2003 - 12:41 AM

AWD is like a helmet, you probably won't need it, but do you really want to be fumbling for it when your spinning head over heals towards the concrete?

#12 wrxsubaru

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Posted 11 December 2003 - 06:07 PM

I saw that nissian comercal and it dident really make any sence, they said the AWD drive hurts handling on the dry pavment, the drive train has little to do with handling (the viscos coupling center diff on most subes barley have any limited slip effect at all and does not cause any real binding be between the axels unless its screwed up), the drivetrain is set up only to get power to the ground, you can get the most power to the ground through all the wheels. The drive train does afect how the car reacts when it is given power, or more power and when you have all wheel drive usally the car has the most controlable changes when the car is given power.

Example If subaru made a WRX with FWD, RWD, and AWD they would all have very close handling limits, but would all react diffrently when you gave it gass, and AWD usally acts to most controlable and is the fastest set up , because you can get more power to the ground.

AWD also improves braking acting as its own anti lock system because the wheels are conected through the drive train. It helps alot more than most people think, ecpecialy with a car with out ABS.

Also the Nissian Skyline is primarily RWD but when it dectes slip it locks up so its AWD.

#13 alias20035

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Posted 12 December 2003 - 01:20 AM

Originally posted by wrxsubaru
AWD also improves braking acting as its own anti lock system because the wheels are conected through the drive train. It helps alot more than most people think, ecpecialy with a car with out ABS.



AWD does lock the front and rear axles together making it harder to lock up the brakes, except when on really slick surfaces such as ice where it makes no difference at all.

ABS tracks vehicle speed off of the fastest spinning tire, usually a rear wheel. AWD interferes with this by causing all wheels to lock together, and this makes ABS on AWD less effective. You also want free axles during skid recovery, interlocked axles really complicates skid recovery.

Subaru 4EAT AWD will mostly disengage during ABS application to reduce this problem, but the viscous coupled 5MT can not.

Subaru introduced the G sensor to its 5MT AWD cars long ago to provide an additional braking force input to the ABS system other than wheel speed. The G-sensor measures the deceleration force and alters the brake pulse to obtain the maximum deceleration. G-Force was introduced on 4EAT AWD cars in 96.

Audi's with their American Gleason Torsen center differentials are much better off, since the torsen diff only reacts to driven torque and not braking torque. Quattro virtually shuts off during braking.

I went head to head with my neighbours Audi A6 Quattro wagon with identical Michelin Arctic Alpin tires on an frozen lake last year. I had more traction for better acceleration and powered maneouvers, but the Audi solidly beat me in braking distance and maneouvering under braking. We switched cars and the results where the same. The Audi stopped some 10 m (~30 ft) shorter than my Outback from 50 kph (30mph), 10m = 2 car lengths.

I like to say that AWD is a safety advantage that you should keep in your back pocket, if you find yourself using it, it has ceased to become a safety advantage and you are just pushing your luck.

#14 Setright

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Posted 12 December 2003 - 07:37 AM

Alias, that test only proves one thing: that particular Audi had a shorter braking distance on that particular lake, compared to that particular Subaru. You cannot infer any further conclusions.

You could argue that most likely the Audi has better brakes. But it is not a certainty.

The weight, weight distribution, tyre pressure, suspension geometry, center of gravity, and other aspects of each car will have a profound influence on the braking distance. Not to mention the type of ABS system, in particular the frequency of the brake line pulses. For sure the AWD system and it's components are also important, but those two cars are too different to be compared in such a simple manner.

Oh, and Audi/VW have ditched the brilliant Torsen system, years ago. Now they use a Haldex clutch, similar to the old system on automatic tranny Subes. What a shame!




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