AWD - what does it do for you?

I'm sure half the people clicking on this will think I'm asking a question, and the other half that know I've been driving turbo legacies for some 5-6 years know I've found the gin again. ;) But I do see a lot of new faces here, and there will be more in the future. So I'm here to talk about the reality behind the hype. Is AWD magical? In and of itself, no. There are a lot of drivetrain choices that are labeled AWD that will do little for you in reality, besides getting yourself going out of a poor traction situation that you likely shouldn't have gotten yourself into in the first place. Subaru's system isn't very complex, it doesn't do a lot of neat tricks, and it isn't the latest and greatest. What it is is the mountain goat of AWD systems - it works *very* well, it is rugged, it is more efficient with less parasitic loss than most other full-time AWD systems, and it's lack of electronics makes it predictable. Doesn't having AWD mean that I have more traction? Nope. No, really. You don't. Seriously. You simply have a more balanced distribution of torque to the wheels, which is allowing better control of the traction that *is* there. What that means is that in braking and cornering, in equally balanced cars of equal rubber size and composition, equal weight, basically, everything equal - they will have exactly the same levels of corner grip whether AWD, RWD, or FWD. However, if you are cornering under power, AWD vs. the others *does* have some benefits, simply because the power is balanced better among all four tyres than the usual one or two tyres. AWD means I don't need snow tyres for snow. No. See above - you don't have more traction. You simply have more ability to get moving in a straight line. And if you learned to drive in a studly rally style like I did delivering pizzas in the snow for 3 years, you can use that straight line traction in corners - ie, you will be totally sideways and using that straight line traction to keep you going "in". But you know what? I learned that in a RWD. Anyways, you still need the snow tyres for *cornering* and *stopping*. If you don't think so, you have not gone down a significant incline in the snow without snow tyres. But I've been driving in the rain in my RWD or FWD and I never have any traction! That's likely because you have been putting cheap tyres on your cars. I've been to the race track in enough situations, in the rain, to find out that it is the tyre that gives you the most traction in the rain (or any other condition), not the drivetrain layout. If that is the only reason you bought into AWD, I'm sorry to say that you could have saved yourself a lot of money and just got some good tyres for your previous ride for once. So you are saying AWD doesn't perform better than RWD/FWD in corners? No - it does. But it only does that at levels of handling that few of you are ever going to experience, other than doing something stupid. And the problem with doing something stupid is that eventually you will exceed physics, and nothing, and I mean nothing, no electronics, no AWD system, will save you. What AWD does is give you far better balance when going through the corner by reducing the amount of power to any single wheel, or any single end of the car, by distributing it among all four tyres front to rear. This allows a far higher level of balance under power going through corners than many people have ever experienced before. I must state, though, that a professional driver in RWD or FWD *has* been able to be that balanced. More on that below. AWD also gives you far more apex options and exit options under power. But many of you really don't know what that means... AWD and balance. Car control is about balance, about weight shift and control. The overriding problem with cornering is that you do not have equal traction at all wheels when you are cornering, you usually have the majority of weight *on one tyre* with the other 3 tyres playing lessor roles. Usually it is the outside front tyre that is taking the most weight. The rear tyres get the least. Thus the reason RWD tends to oversteer, ie, the rear slides out, when under power. FWD can be made to oversteer as well, if you know how to shift weight well. Now, AWD manages to balance the power while going through corners better than RWD or FWD - you see, under power, the front of the car lifts and the weight shifts to the rear. So AWD is faster. Yes and no. It is easier to go faster. And it is far easier to get to the limits of the car for all drivers, especially beginners. This is one of the reasons that it is possibly a very bad car for beginners. Huh? AWD lies to you. It coddles you, it makes you feel safe, it allows you to get to the limits easier. The problem is, the distance to going over the limits becomes much *shorter*. RWD teaches you respect a lot faster and earlier, FWD just understeers. AWD lets you shoot so far up, when you go over, you won't be able to recover. Thus I feel it may be very bad for inexperienced drivers, in a way, for it may encourage people to drive beyond their skill limits. People do that anyways, but in AWD, when you go off, you tend to *really* go off. Hmm, gin is wearing off... Cheers, Paul Hansen [url]www.apexjapan.com[/url] your friendly car tasters

Blah blah blah AWD will help my wife drive up our long dirt drive in the winter here in Colorado... AWD in my Polaris 700 Twin ATV helps me plow off the snow in the winter Traded in my wife's Maxima for this car to get her up Ute Pass in the Winter....tired of getting a front end loader to pull her Maxima out of the snow because she couldn't make it up the driveway Mark Woodland Park, CO 8600 feet elevation

Which makes me glad high-powered AWD cars were not my first vehicles. Well written Paul. Bravo! 8)

So...car manufacturers that provide traction control systems should change the name to torque distibution systems?

Wow! Thank you, apexjapan, for you superbly written and instructive post. I appreciate it. It makes me think that maybe my FWD car was safer. It seems, for some odd reason, that I'm a bit more aggresive with the Legacy GT.

I agree with some of the stuff you posted, but obviously an AWD car will do better in a race if the drivers are exactly the same. Hence the reason the WRC cars uses AWD, as well as the reason F1 prohibts AWD as well as many Touring car races prohibit AWD. And in races where they do allow AWD they usually have to carry extra weight because of the advantage AWD brings. AWD does give your car more control in turns and does allow you to accelerate faster and quicker out of a corner then FWD or RWD cars. This is the reason they put our cars in special classes in Auto-X's or Races. I do agree when you say AWD can install to much confidence in a person, causing them to reach their limit quicker which will cause them to screw up quicker. It happened to me so I know first hand. But you live and learn, and I learned from my mistake and decided the best place to learn was at Auto-X's and Track events where I eventually became pretty competitive. Probably the thing I agree most with from your post is, AWD doesn't help you brake any better. Nothing is more true then that. But AWD does help in corners, although a good set of snow tires on a FWD car will beat a AWD car with all seasons. So if you really want to be safe in the snow get some snow tires, otherwise your just a little better and accelerating and turning then FF and FR drive cars. I think the best thing a person can do though is to get out to a auto-x, just do it 2-3 times and you will learn a lot about what your car can and can't do. You will find its advantages and disadvantages. Like said above AWD isn't magic, but I do think it helps more then what you were saying, you just need to learn about it and learn how to use it right, once you do that you can truly apreciate the car subaru built. A few days ago I remember watching a Touring car race, an Audi with AWD went off the track at high speed. It looked like he was trying to pull the car back on, but he had so much momentum going forward the AWD did nothing for him, he just ended up hitting the brakes and flying into a tire wall. So just like every car, if you go past its limits nothing will save you. So learn its limits and yours.

Man, I need to put a history down or something - I've been at the track with the Legacy (and so has apexjapan2) quite a bit. And not the autocross, but proper circuit tracks - twin ring motegi, tsukuba, and fuji speedway. I'd be the first to agree that it certainly works on the track. 5-6 years of experience proving that. ;) But physics are physics, AWD doesn't exceed the limits better, it just makes it easier to get near the limits. Few people really know the actual limits - I've been lucky to drive with professional drivers that do, and there is simply a world of difference. Proper knowledge of the cars limits, and your limits, is the most important thing in the world when it comes to driving. It reminds me of a tale written by a good driver, a good writer. A reporter was in a Supra twin turbo, testing it at the track some time near it's introduction. Now, he was probably better than most of you on the track, and he was pushing it hard. Going through the corners, he noticed a toyota corolla on the track behind him at the same time. Didn't pay much attention. A couple of corners later, he looked again. It was closer. Now he really started to drive hard, no way a corolla was going to catch him in the sports rocket. Several corners later, David Coulthard, grinning ear to ear, passed him in the Toyota Corolla. A lot of WRX owners shunted into trees and ditches early on because of the way an AWD lies to you about traction and limits, and a lot of new people are coming into the Subaru fold for the first time. I am seeing lots of tales of "wow, I was pushing the Legacy GT, and the tyres never squealed once!". And all I can think is, I could get them screaming like pigs just leaving the dealer lot. Apexjapan2 would have had them screaming just leaving the dealer parking space. But we've both been doing this for a while, people have this tendency to want to explore the limits, and in the absence of the usual feedback, I worry about the accidents that are bound to happen... Hrm, drinking and writing don't mix well either. Cheers, Paul Hansen [url]www.apexjapan.com[/url] your sloshed car tester

I wish I had some track (circuit) experience! The closest I've come to that is an oval track, and as fun as that was, I want more. I'd really like to drive around twin ring motegi, tskuba, fuji speedway, etc. One can dream I suppose.

Oh, it is a lovely, incredible, and horribly expensive experience. Everybody should do it a few times to teach themselves what fast corners really mean, and how bad skyline GT-R drivers are. And why you don't want to do it again unless you really have money to burn. Think brake pads are expensive now? Wait till you burn through a set in one track day. Along with your tires. And your oil. And brake fluids. One driver went off after the track on the way home because he had totally overcooked his brake system. My dream is to be able to beat on cars for free - I don't mind not getting paid, at least I'm not paying! Cheers, Paul Hansen [url]www.apexjapan.com[/url] your semi-drunk track monkey

So your saying if you lined up a peugot 307 and modded it exactly like a WRC car except left it FF, you would say it would perform just as well as a peugot 307 WRC car with the AWD powertrain (obviously the same driver in both cars)? I know what your trying to say in your posts, but it seems to me that you are trying to make AWD seem like it has no use exect to accelerate in a straight line in the snow. And I have no doubt a good driver in a lowly corolla could beat someone in a twin turbo supra. Here is a quote from a guy who passed away a couple years ago who was on clubwrx.net (wasn't a car related death). "The most important mod is the one behind the steering wheel" - Koyokid

Frequently the FWD rally cars are faster than the AWD cars - on tarmac stages. ;) But that is also because they are not equal, and that is life. The FWD cars are lighter, and they don't have as much problems getting the power down to the ground in the dry. Anyways, I pointed out in several places that AWD does improve balance and power delivery in corners. It's just that it doesn't increase traction. The 4 patches on the ground are the same, regardless of the drivetrain above it. AWD just improves how you pass the torque to the ground through those patches. Cheers, Paul Hansen [url]www.apexjapan.com[/url]

[quote name='apexjapan']Oh, it is a lovely, incredible, and horribly expensive experience. Everybody should do it a few times to teach themselves what fast corners really mean, and how bad skyline GT-R drivers are. And why you don't want to do it again unless you really have money to burn. Think brake pads are expensive now? Wait till you burn through a set in one track day. Along with your tires. And your oil. And brake fluids. One driver went off after the track on the way home because he had totally overcooked his brake system. My dream is to be able to beat on cars for free - I don't mind not getting paid, at least I'm not paying! Cheers, Paul Hansen [url]www.apexjapan.com[/url] your semi-drunk track monkey[/quote] Which is true! It does get expensive...I didn't say I wanted to be a track monkey (unless it was paid for as you noted of course) but it sure would be fun to drive on them! :D

Most interesting thread on this forum to date, lets all send Paul a bottle of Gin :twisted:

Very informative posts, Paul! I see what you're saying about traction being what it is and AWD not changing that, but I'm having a hard time "coming to grips" with it. It is agreed that traction is simply the four contact patches of rubber on the road. As an example...accelerating from a right-hand corner. In a FF car, as you accelerate, weight transfers from the front wheels to the rear - particularly the left rear. Theoretically, this would exascerbate understeer, or could help correct oversteer if you had managed to induce it earlier in the turn. BUT, it also takes weight off the front wheels, thus reducing the area of those two contact patches. Granted, you now have more "traction" on the rear wheels by the size of the contact patch being increased, but those wheels are just dragging along for the ride. So...overall, you are lessening traction in this scenario. In the exact same scenario in an AWD car, that acceleration out of the turn still transfers weight from front to rear. However, the rear wheels are powered, unlike the FF car. So, traction lessens on the front wheels but increases on the rear, thus retaining relatively constant net traction unlike the FF car. Come to think of it, I guess we need to define traction. In this case, I'm referring to the difference in lateral traction (same for both cars) and forward traction (greater for AWD). Or am I way off?

the last time i went on a track day, i spent $$$ on gas not to mention melted my then brand new S03s! and that's with alot of 'in-between' rests. but chasing down a Dodge Viper on some tight twisties is quite satisfying. So for now, i will stick with autocross.

Knowledge is power! Thanks Paul for providing that informative post. I don't have anything to contribute, except that I learned a lot. :)

[quote name='apexjapan']........AWD means I don't need snow tyres for snow. No. See above - you don't have more traction. You simply have more ability to get moving in a straight line. ........... Cheers, Paul Hansen [url]www.apexjapan.com[/url] your friendly car tasters[/quote] How do you get this "more ability to get moving in a straight line" from AWD? It must come from the ability to apply more total torque to the ground via the tires. In other words, more traction.

Ok, another history lesson... don't forget there's a reason that AWD is outlawed in the Trans-Am series. They let Audi play a few years back and the 5000-based Quattros were devastating the Camaros, etc. There also was an article in the Sept. Car and Driver about driving impressions of the latest Speed GT cars. The Audi was the easiest to deal with out of the corner exits... surprise, surprise.

Good material here. In summary AWD raises the limits but when exceeded, it looses control just like any other car. Simple enough physics. I'll never go back to FWD or RWD ever again.

[quote name='fan42025']Good material here. In summary AWD raises the limits but when exceeded, it looses control just like any other car. Simple enough physics. I'll never go back to FWD or RWD ever again.[/quote] Nothing wrong with a nice RWD.... :twisted:

soooo..... basically...buy good tires. i knew that. but my tires still suck with 500 miles on them.

[quote name='Drift Monkey']Nothing wrong with a nice RWD.... :twisted:[/quote] Yes, like the new BMW M5 - read the review and it rocks. Tad faster than the GT but way too pricy. It has so many gismos to handle well around corners it makes you wonder what would happen if something failed part way.

Well, I had meant a part.2, but the side effects of the gin are drowsiness and an uncontrollable urge to watch B movies. Somewhere else in a forum far away, somebody brought up the term traction circle. It was used to describe traction forces in all directions, for grip in corners, for instance, is a combination of forward grip and sideways grip (and then there is braking grip). Every tyre has a bit different characteristics in the traction circle - some willl be better in forward grip than side grip, others the opposite, and the best rather well balanced between the two. However, the story doesn't end with the tyres, because there is more to the traction circle. Now, this is where AWD is indeed a benefit because the other major forces that act upon your four contact patches - weight transfer and accelerative forces. In an ideal world when you are going through the corner, all four tyres have an equally large contact patch, thereby giving you max traction through the corner. In reality, at the extreme end you have the outside front tyre with 90% of the grip and the remaining 10% distributed among the other three. This could be described as "kissing your bodywork goodbye". ;) Ok, seriously though, this is why good tyres are so good, because they really can be shouldering that much of a burden on an individual basis. Now, weight transfer is the key to this. When you accelerate towards a corner, the weight of the car is shifted to the back of the car - result, front end traction is lower, rear end traction is higher. If you kept your foot in it and turned, the front usually does not have enough traction because the weight is still at the rear, and will not grip. This is your classic power on understeer. ie, the 350Z. But most people brake right before the corner, then turn. This transfers the majority of the weight to the front tyres, mainly the front outside tyres, and lightens the rear tremendously. This is the beginning of the classic oversteer situation. It is complicated by the fact that there is so much weight on one tyre, however, so that you again can find yourself understeering, because that front outside tyre cannot cope. Of course, you can get around this by getting back on the gas again after you finish the braking and enter the corner. This takes the load off the front and transfers some to the rear. This weight transfer balancing act is the key to racing. But drivetrains react differently to that balancing act. FWD will understeer under power, because you are also transfering the weight from the driven wheels due to the weight shift to the rear. This is why the Integra was set up with a rather "flickable" rear, allowing it to easily break loose so that more traction remains in the front than the rear, giving it a better course through a corner due to a very oversteering nature. RWD will oversteer under power, because you are moving traction to the rear, and then adding another force on the tyres traction circle - acceleration - while going through this corner. Especially on high power cars, this force is quite hard to accurately control when you are already at the traction limits of the tyres. Which is why RWD is known for oversteer, for the fronts have plenty of grip while the rear is heading for the hills. AWD is the combination of these two, in that it is a FWD that also transfers power to the rear as well. It balances the forces better than either of the other drivetrains, lessening the affects of acceleration on the traction circle. It is much easier to control for that reason. That is also why an AWD driver will have many more options when going through a corner, plus they are able to get on the gas much sooner than FWD or RWD drivers because of the balance front to rear even under acceleration. As a matter of fact, because acceleration actually balances the AWD out through weight transfer front to rear, and by moving torque to the wheels with grip, the fastest way through the corner is usually under gas, albeit light gas at first. This is the counter-intuitive part for some people, and a reason why many feel it isn't as fast as RWD. When you drive it like a RWD, which is brake/lift off the gas, and then not getting on the gas till post-apex, the AWD drives like a FWD - understeer. To take advantage of AWD, you have to take advantage of weight transfer, and for that, you have to be friendly with your throttle and brakes. Cheers, Paul Hansen [url]www.apexjapan.com[/url]

Nice. PH...it's like I live in your head. After having watched the video that was recently submitted by a forum member (thanks!), I completely understand what you are talking about. I even know that the Infiniti G35 sedan's driver was not really transferring that power correctly. Thanks for the information...you hit my thoughts right on the head. No, I have never raced..but thanks for this info. I am sure it will if I decide to. Later, i.

Paul, that's it! On the wagon for you! :wink: I may be well known for getting cars to go sideways off the line or through corners for photo shoots, but in general I much prefer the grip method on Joe Public's roads ;) One thing I am genuinely well known for though, is budgeting for a tyre change for a new car almost immediately after purchase (depending on the rubber on them when new of course). "Almost immediately" can be anything from up to the end of run-in, to as long as it takes to get my tyre place of choice :wink: The newest Legacy has good tyres in Japan, but even my B4 when brand new had way too much performance for the rubber, and P7000s mysteriously found their way on to the beast shortly after purchase. They were good when new, but went down hill fast. Since then Michelin Pilot Sports (rubbish), Potentza S-03s (excellent once through the slippery top layer), P-Zeros (great for 5000km in the dry, positively terrifying in the wet after about 3000), and Potenza RE-01s (still great after 27k!!). Sadly the RE-01s are not exported, but the S-03s are still the ones IMHO - Bridgestone for some reason is still the only maker trying to make sure their tyres grip well until they wear out - others continue to build rubber that is great when new, then seems to die before the wear indicators are even threatened. I feel that they are worth the extra dollars for peace of mind, but each to his own :) All IMHO of course. Cheers :)