Subaru - best AWD technology?

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Originally Posted By: IndyIan
True, mechanical AWD and 4WD , do help with braking as they equalize light braking forces from front to back. Both axles want to turn at the same speed as locking the front axle with AWD requires the engine do drop down to half the rpm. ABS is nice but to get maximum braking you've got to stand on the pedal sending the front axle into full ABS mode to get enough braking to get the back axle involved. With a mechanical link between the axles, both of them can be used at near full braking without ABS getting involved at all. My wife noticed right away switching back front true 4wd in winter to gizmo AWD, that the front tires use ABS all the time on braking... Now I don't think even subaru makes a true mechanical AWD (center differential)system anymore, so the electronic gizmos and clutches try to simulate one. I find in low traction situations though, the simulated AWD systems rely on some amount of slip to activate and then the amount of friction on sliding tire on ice or snow is much less than static friction. Then they brake the spinning tire(s) cutting momentum...

1. ABS activation doesn't necessarily correlate with stopping distances. Did you test those?

2. If you have different cars, then you have different tires, weight distribution, suspension geometry, etc. How did you control for those?

3. Are you talking about a fixed torque split, or fully locked axles? The latter would be... not good on the street.

4. You're describing a situation in which the wheel speed equalization effect of the powertrain overwhelms the additional mass in the powertrain and the way it would confound the operation of the ABS. Sounds like something that -- if it even works -- would be most relevant to an old car with highly primitive ABS, not one with modern ABS and electronic brakeforce distribution.

5. Even if this all played out the way you're suggesting and was directly attributable to the AWD/4WD, it wouldn't be particularly relevant because it'd only apply in an "all else equal" situation -- i.e. two of the exact same vehicle with the same tires and roughly equal curb weights, but with different AWD/4WD systems. Doesn't really exist in the real world. Vehicles with the type of system you're talking about tend to be heavier than vehicles without, and the added momentum increases stopping distances in all conditions.
 
Originally Posted By: d00df00d
Originally Posted By: fdcg27
Drive one yourself in snow and you'll see my point.
I'm not going to debate theory.
The proof is in the driving.

I have. Repeatedly.

I've also done side-by-side brake distance tests between my old RWD car on winter tires and an AWD Subie on all-seasons.

I also have many friends who have gone back and forth between RWD + winter tires and AWD + all-seasons, with the same results.

I have no idea what you're talking about. No one I know has any idea what you're talking about. I can't find a single third-party source that doesn't say the opposite of what you're saying.

So, again: waiting for you to clarify.


Braking is not generally an AWD related item. It is tires, tires, and... tires... and then the brakes. AWD vehicles, with the same tires as a RWD could actually take longer to stop because of weight compared to its 2wd counterpart. (About 400lbs+). However... if you need "more" weight over the wheels, that extra 400lbs normally riding low in the vehicle can provide a benefit in some snow conditions. Not always, but sometimes. So saying "no" in all cases is wrong but in some "difficult conditions" which is what fdcg27 can be correct. Subarus work well in a lot of the winter/snow conditions because they are heavier than other 2WD options... but also be a liability. I used to load in an extra 240lbs over the rear axle for a bit more rear grip in deep wet snows.

It definitely can help with steering. Having power to the front wheels always helps in lower-speed, light-to-moderate torque conditions. It is what makes a FWD car "zip" around parking lots. Unlike a RWD car, which the wheels are basically passively searching for grip, having power up-front allows you to search for traction and will make a turn-in in bad conditions happen faster. Especially if you have a front-heavy vehicles that can push through snow/slush to find grip. So FWD and AWD vehicles have that steering advantage over RWD vehicles in winter conditions. Don't believe me? Drive a MR2 (or any rear/mid placement vehicle) in the snow. With 38% of the weight in the front, the front tires can only do so much. I can get going easily enough but steering can be a a big delay affair in the snow. I can turn the wheel hard and still power-on in a straight line with the throttle (back bites and hunkers down reducing the traction on front). It can be fun too... but not if you are seriously trying not to get stuck. I have to actively think about transferring the weight to the front if I am going to steer that thing in the winter. That is now why it has summer tires and is a 9 month car only.

I have and currently drive a front-engine-rear-wheel and a mid-engine-rear wheel vehicle in the winter/snow. You *can* do it. However, if my Ginny looses traction in the rear, it can't claw itself out. If the Subie looses rear, the front wheels (hopefully) can pull it out. I work in a public safety office. I don't get snow days and I am a designated "winter driver" for my agency for specific necessary trips. I need AWD. Still, I can get by with RWD... but you are kidding yourself if AWD does not work and that Subaru makes one of the best winter-weather AWD systems. You can tell by how the components work (and I actually thing their newer vehicles are are better in the snow than their older models... as a general rule, but there are exceptions).

RWD is more fun with a light dusting. Just enough for some slip without being dangerous. This would cause Carmageddon in Atlanta as they all have bald summer tires.

IMAG1857_zpsezfcqewo.jpg
 
Originally Posted By: d00df00d
Originally Posted By: IndyIan
True, mechanical AWD and 4WD , do help with braking as they equalize light braking forces from front to back. Both axles want to turn at the same speed as locking the front axle with AWD requires the engine do drop down to half the rpm. ABS is nice but to get maximum braking you've got to stand on the pedal sending the front axle into full ABS mode to get enough braking to get the back axle involved. With a mechanical link between the axles, both of them can be used at near full braking without ABS getting involved at all. My wife noticed right away switching back front true 4wd in winter to gizmo AWD, that the front tires use ABS all the time on braking... Now I don't think even subaru makes a true mechanical AWD (center differential)system anymore, so the electronic gizmos and clutches try to simulate one. I find in low traction situations though, the simulated AWD systems rely on some amount of slip to activate and then the amount of friction on sliding tire on ice or snow is much less than static friction. Then they brake the spinning tire(s) cutting momentum...

1. ABS activation doesn't necessarily correlate with stopping distances. Did you test those?

2. If you have different cars, then you have different tires, weight distribution, suspension geometry, etc. How did you control for those?

3. Are you talking about a fixed torque split, or fully locked axles? The latter would be... not good on the street.

4. You're describing a situation in which the wheel speed equalization effect of the powertrain overwhelms the additional mass in the powertrain and the way it would confound the operation of the ABS. Sounds like something that -- if it even works -- would be most relevant to an old car with highly primitive ABS, not one with modern ABS and electronic brakeforce distribution.

5. Even if this all played out the way you're suggesting and was directly attributable to the AWD/4WD, it wouldn't be particularly relevant because it'd only apply in an "all else equal" situation -- i.e. two of the exact same vehicle with the same tires and roughly equal curb weights, but with different AWD/4WD systems. Doesn't really exist in the real world. Vehicles with the type of system you're talking about tend to be heavier than vehicles without, and the added momentum increases stopping distances in all conditions.

Our CRV has electronic brake force distribution and is fwd vehicle in terms of braking. It still is overly biased to lock the front tires first on snow and ice, IMO. The CRV replaced a 2003 Tracker rwd/4wd (without ABS) and coincidentally they both had Xice tires worn about the same amount, down to 6-7/32. Now the CRV is 500lbs heavier but my wife noticed the most difference while braking on slush (which should help the heavier vehicle), and wondered what was wrong with with CRV as the ABS would start clicking away on the fronts while the car wasn't slowing down... Perhaps it was mostly due to the weight difference, but I think its more than that. With the front and rear axles tied together you can feel all 4 tires working when you get near the limit in braking.
I guess someone with a newer 4wd pickup could do some snow braking testing in 2wd and 4wd mode. I suspect even with all the electronics, a mechanical link will help reduce braking distance noticeably.
 
Originally Posted By: d00df00d
Originally Posted By: fdcg27
Drive one yourself in snow and you'll see my point.
I'm not going to debate theory.
The proof is in the driving.

I have. Repeatedly.

I've also done side-by-side brake distance tests between my old RWD car on winter tires and an AWD Subie on all-seasons..


I completely agree that tires make a huge difference. I too am a third Subaru owner and all have been later models (2012 and up). I can't pinpoint exactly what it is, but I suspect SOA has REALLY cheaped out on factory tires in recent years, where years back, they came with better tires from the factory. Reason I say this is, all the older Subarus in my family were TANKS in the snow compared to how my 2012 Legacy and 2014 XV Crosstrek were and my 2016 Forester is. The only one I had long enough to equip with snow tires was my Legacy, which I threw a set of used Firestone Winterforces on. Those made it much better. My 2016 Forester @ 26K miles is marginally terrifying in slippery conditions with the factory Yokohama Geolanders on it.
 
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Originally Posted By: JTK
factory Yokohama Geolanders on it.


^ Nailed it here. Geolanders are notoriously bad in the snow.

Subaru has been using a lot of Continental Pro-Contact on in past years which are good in the snow although have poor treadlife IMO. I shook my head when I saw the Geoloanders on a new Forester.

Again, tires are important to get grip.
... but they can power you out of a spot either.
 
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Clarified it for you.
Drove the car, was amazed at both cornering and braking ability in fresh wet snow.
Accord on Bridgestone dedicated winters was good but not as good.
You either get it or you don't.
Don't know what else to tell you.
Perhaps we'll just agree to disagree?
 
This is interesting.
The Geolanders that came on our '09 Forester seemed pretty good in the snow.
OTOH, we had a since departed member here who had bought a later Forester for his wife who found the OEM Geolanders so scary that he put another set of tires on a then six month old car.
There are apparently different Geolander versions with different levels of winter grip.
There are also different levels of driver comfort and skill in winter conditions.
Those of use who grew up driving in real winters, like my wife and me, are probably more comfortable driving in it than are those to whom it's something new and unpleasant.
What I describe as awesome winter handling another driver might describe as terrifying.
It's all a matter of what one's used to.
 
I've heard a lot of complaints about the stock Forester tires in snow lately. I suspect Subaru decided that people who really care about snow performance were putting snow tires on the car.
 
Originally Posted By: emg
... I suspect Subaru decided that people who really care about snow performance were putting snow tires on the car.


Which is kind of ridiculous for a vehicle who's niche in the market IS it's snow-worthiness. To be fair though, it's not just SOA. It's all the competition too.
 
Originally Posted By: IndyIan

Our CRV has electronic brake force distribution and is fwd vehicle in terms of braking. It still is overly biased to lock the front tires first on snow and ice, IMO. The CRV replaced a 2003 Tracker rwd/4wd (without ABS) and coincidentally they both had Xice tires worn about the same amount, down to 6-7/32. Now the CRV is 500lbs heavier but my wife noticed the most difference while braking on slush (which should help the heavier vehicle), and wondered what was wrong with with CRV as the ABS would start clicking away on the fronts while the car wasn't slowing down... Perhaps it was mostly due to the weight difference, but I think its more than that. With the front and rear axles tied together you can feel all 4 tires working when you get near the limit in braking.
I guess someone with a newer 4wd pickup could do some snow braking testing in 2wd and 4wd mode. I suspect even with all the electronics, a mechanical link will help reduce braking distance noticeably.


99% of cars I've tested on the rollers are front brake biased so no surprise there. So far the only car that has a clear rear brake bias (excluding trucks and big vans) is my own car. there the rears lock up with much less brake pedal travel than is needed for the fronts. It makes for a very engaging drive and you can definitely use the brake as a steering aid but on uneven road suraces you're sure to trigger the ABS under moderate to heavy braking. Well, the rear wheels will nearly always be on edge of slipping and EBD will be reducing the brake effort constantly. I've got a Continental ABS system, that's pretty rare in my eperience.

I was wondering if this would help in braking under slippery conditions but I haven't seen any noteworthy amounts of snow/ice since I got this car in 2013.
 
The problem with Subaru AWD is the rest of the car to which it is attached....

We have a small fleet of new Foresters at work and I am not impressed. So I drive the our last remaining Honda, and I HATE Hondas.
 
Originally Posted By: FutureDoc
Braking is not generally an AWD related item. It is tires, tires, and... tires... and then the brakes. AWD vehicles, with the same tires as a RWD could actually take longer to stop because of weight compared to its 2wd counterpart. (About 400lbs+).

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Originally Posted By: FutureDoc
However... if you need "more" weight over the wheels, that extra 400lbs normally riding low in the vehicle can provide a benefit in some snow conditions. Not always, but sometimes. So saying "no" in all cases is wrong but in some "difficult conditions" which is what fdcg27 can be correct. Subarus work well in a lot of the winter/snow conditions because they are heavier than other 2WD options... but also be a liability. I used to load in an extra 240lbs over the rear axle for a bit more rear grip in deep wet snows.

It definitely can help with steering. Having power to the front wheels always helps in lower-speed, light-to-moderate torque conditions. It is what makes a FWD car "zip" around parking lots. Unlike a RWD car, which the wheels are basically passively searching for grip, having power up-front allows you to search for traction and will make a turn-in in bad conditions happen faster. Especially if you have a front-heavy vehicles that can push through snow/slush to find grip. So FWD and AWD vehicles have that steering advantage over RWD vehicles in winter conditions. Don't believe me? Drive a MR2 (or any rear/mid placement vehicle) in the snow. With 38% of the weight in the front, the front tires can only do so much. I can get going easily enough but steering can be a a big delay affair in the snow. I can turn the wheel hard and still power-on in a straight line with the throttle (back bites and hunkers down reducing the traction on front). It can be fun too... but not if you are seriously trying not to get stuck. I have to actively think about transferring the weight to the front if I am going to steer that thing in the winter. That is now why it has summer tires and is a 9 month car only.

I think there's a disconnect between what I tried to communicate and what you read. I did oversimplify some points, but I was also pretty careful not to use absolutes. Of course there are handling advantages to AWD, and traction advantages to extra mass.

On the point about mass, I think what you're getting at is ground pressure. The more you have, the more easily your car will punch through whatever's on the road (rain water, snow, slush, etc.) and find pavement. So yeah, it's definitely true that a heavier vehicle will have a few advantages. I'll even expand on that for you: a heavy car -- as long as its center of gravity is nice and low -- will have more predictable and intuitive traction and handling characteristics. Its grip level will change less on different surfaces, and everything it does will be slower. That's an advantage for sure -- not because it makes the car more capable, but because it makes the car easier to work with. That's part of why the Nissan GT-R was made to weigh almost 4000 lbs, for example. It generates its ground pressure more through mass and less through aerodynamic downforce than most other supercars. That makes it an easier car to exploit, especially in poor conditions.

Yes, power at the front axle, as well as a front-heavy weight distribution, will make the front end work more intuitively and positively in low-traction low-speed situations. The way they help avoid getting stuck is something I've already touched on. On the point about powering out of a corner, I think it's a stretch to call that a "steering" advantage; it seems more like an acceleration advantage to me. However, for most drivers, there's a lot to be said for an inherent understeer bias and simple limit behavior, even if it comes at the expense of the car's ultimate ability to change direction.

So yeah, advantages all around. But that doesn't really get us anywhere. As always, the real question is, what's the overall effect? Mass is one step forward (ground pressure) and two steps back (momentum, inefficiency, tire/brake/suspension wear). AWD is a godsend for acceleration, a mixed bag for cornering, essentially irrelevant for braking, and a liability for efficiency and upkeep. So, a heavy AWD vehicle will have features that are good, bad, and indifferent. Season-appropriate tires, on the other hand, have pretty much nothing but upsides no matter what kind of car you have. And they greatly improve performance in safety-critical areas that AWD either helps and hurts at the same time, or straight-up can't touch. So, if the choice is between AWD and season-appropriate tires, you should always take the tires. And if the particular advantages of AWD are make-or-break for you -- which they aren't for >99% of people -- then you should take that AND the tires. That's my point.
 
Originally Posted By: IndyIan
Our CRV has electronic brake force distribution and is fwd vehicle in terms of braking. It still is overly biased to lock the front tires first on snow and ice, IMO. The CRV replaced a 2003 Tracker rwd/4wd (without ABS) and coincidentally they both had Xice tires worn about the same amount, down to 6-7/32. Now the CRV is 500lbs heavier but my wife noticed the most difference while braking on slush (which should help the heavier vehicle), and wondered what was wrong with with CRV as the ABS would start clicking away on the fronts while the car wasn't slowing down... Perhaps it was mostly due to the weight difference, but I think its more than that. With the front and rear axles tied together you can feel all 4 tires working when you get near the limit in braking.
I guess someone with a newer 4wd pickup could do some snow braking testing in 2wd and 4wd mode. I suspect even with all the electronics, a mechanical link will help reduce braking distance noticeably.

500 lbs, when the CRV weighs 3300-3500 lbs depending on spec... that'd put the Tracker at 2800-3000 lbs, right? Percentage-wise, that's quite a big difference.

Someone will definitely have to run the test somehow. Not sure how applicable it'd be, but it might be interesting at least.
 
Originally Posted By: fdcg27
Drove the car, was amazed at both cornering and braking ability in fresh wet snow.
Accord on Bridgestone dedicated winters was good but not as good.

Hope I don't have to explain why "amazed" and "good" don't really accomplish much in terms of clarification.

I have no doubts about your sincerity. I'm sure you're conveying your subjective experiences accurately. It's just hard to know what to make of what you're saying.
 
Originally Posted By: d00df00d
Originally Posted By: FutureDoc
It definitely can help with steering. Having power to the front wheels always helps in lower-speed, light-to-moderate torque conditions. It is what makes a FWD car "zip" around parking lots. Unlike a RWD car, which the wheels are basically passively searching for grip, having power up-front allows you to search for traction and will make a turn-in in bad conditions happen faster. Especially if you have a front-heavy vehicles that can push through snow/slush to find grip. So FWD and AWD vehicles have that steering advantage over RWD vehicles in winter conditions. Don't believe me? Drive a MR2 (or any rear/mid placement vehicle) in the snow. With 38% of the weight in the front, the front tires can only do so much. I can get going easily enough but steering can be a a big delay affair in the snow. I can turn the wheel hard and still power-on in a straight line with the throttle (back bites and hunkers down reducing the traction on front). It can be fun too... but not if you are seriously trying not to get stuck. I have to actively think about transferring the weight to the front if I am going to steer that thing in the winter. That is now why it has summer tires and is a 9 month car only.

...On the point about powering out of a corner, I think it's a stretch to call that a "steering" advantage; it seems more like an acceleration advantage to me. However, for most drivers, there's a lot to be said for an inherent understeer bias and simple limit behavior, even if it comes at the expense of the car's ultimate ability to change direction.

Apparently I somehow reprocessed your point about turn-in into a point about exiting corners. My apologies. Don't think this changes the thrust of my argument, but I wanted to make the correction.
 
Originally Posted By: horse123
Can't even imagine driving some giant brick of steel SUV with a V16 or some crazy [censored] that tries to make it look cool on paper. I like my handling
cool.gif



+1
 
Originally Posted By: JTK
Originally Posted By: d00df00d
Originally Posted By: fdcg27
Drive one yourself in snow and you'll see my point.
I'm not going to debate theory.
The proof is in the driving.

I have. Repeatedly.

I've also done side-by-side brake distance tests between my old RWD car on winter tires and an AWD Subie on all-seasons..


I completely agree that tires make a huge difference. I too am a third Subaru owner and all have been later models (2012 and up). I can't pinpoint exactly what it is, but I suspect SOA has REALLY cheaped out on factory tires in recent years, where years back, they came with better tires from the factory. Reason I say this is, all the older Subarus in my family were TANKS in the snow compared to how my 2012 Legacy and 2014 XV Crosstrek were and my 2016 Forester is. The only one I had long enough to equip with snow tires was my Legacy, which I threw a set of used Firestone Winterforces on. Those made it much better. My 2016 Forester @ 26K miles is marginally terrifying in slippery conditions with the factory Yokohama Geolanders on it.


Was this before the period when Subaru used Bridgestone Potenza RE92 where possible?
 
On Awd vs winters tires with 2wd there still are many advantages to Awd Subaru on all-seasons. After a snow dump I can motor out or over snow piles in a parking lot without a 2nd thought. Ski area parking lots after a snow day are quite revealing of the different choices of vehicle and winter tire or not.

I have never gotten stuck in my Awd Subaru that has pure mechanical bliss running a viscous coupling and rear LSD. However I do see red/fwd stuck with winters requiring shovels of snow or push.

That all being said winter tires are optimal however it's a choice whether you need them in your daily life. Coastal NH not needed and in our mountains we have things called plows and salt/sanders to take care of roads near majority of drive time.
 
I've seen the opposite... AWD can't make it up the small incline to the parking at work (dealership) without winter tyres but fwd makes it up if they have winter tyres. Including my own, and the Michelin Crossclimates on those are likely closer to all-seasons but do have the 3pms symbol.
 
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