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(Popular Mechanics)   AWD is over-rated because some reporter who test drives the car, and parks in an underground garage thinks AWD isn't needed and snow tires will do. Wait till he sees the pictures from Lancashire today   (popularmechanics.com) divider line 185
    More: Dumbass, AWD, parking garage, Dodge Viper, laws of physics  
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13204 clicks; posted to Main » on 24 Mar 2013 at 7:31 AM (1 year ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



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2013-03-24 02:39:45 PM  

ha-ha-guy: rohar: Funny, mechanical systems do what you just stated only computer based systems can.  Purely mechanical also means infinitely variable.  This isn't possible with electronic systems.

As someone who works for a company with a test track, I'd think you'd know this...

Please post the diagram for the mechanical system where the car can detect icy conditions, adjust its suspension to move weight around (if considered useful), tell the ECU to act differently with torque production on a direct injected engine, and also inform the ABS and Traction Control to act differently than they do in "sport mode", favor 50/50 power balance over a sport configuration, etc.

I'm sure it can be done, I'm also sure a microprocessor can do it while adding a lot less weight to the car.  Modern cars should not and do not operate with each system in isolation.  They all talk on the car's computer network and make decisions based on input from various sensors, etc.

/if you want an example go look at Audi's Quattro system and notice the mechanical limitations of the Torsen and why Audi added in a computerized system that limits wheel spin using the braking system
//so suddenly the car's computer is using the ABS system to detect while spin caused by a AWD limitation and then using the brakes to prevent wheel spin
//oh look computers make everything better when they link multiple systems on the car
/in less than decade we'll be using the pedestrian / night vision cameras on the car to sense possible icy patches and the car will determine it is about to hit an icy patch and preemptive take action as opposed to waiting for some mechanical system to react, mechanical systems cannot be proactive anywhere near the level the mechanical ones can be


Your premise falls apart right there doesn't it?  Getrag has the ATB devices they have and refuse to innovate.  About 20% is their minimum bias.  You seem to be stuck in the same place.

Why would it matter if it's snowing, raining or the zombie apocalypse?  Either the wheel has grip or it doesn't.  Kinda straight forward isn't it?
 
2013-03-24 02:49:00 PM  
Csb - I drive a plow truck. (Eip if you want a pic of what I drive) awd fwd rwd whatever. Hiw about you stay tge fark off the road and let us do our job?
That coffee that you need, or the 2 litres of milk is unimportant.
Unless someone is dying stay off the farking road. All you wanna be Dale Earnharts just makes our job that much slower and harder.

Tl; dr stay off the road and let highways do their job.
 
2013-03-24 02:54:37 PM  

rohar: Why would it matter if it's snowing, raining or the zombie apocalypse?  Either the wheel has grip or it doesn't.  Kinda straight forward isn't it?


So let me get this straight, your argument is one a wheel loses traction, it stops mattering?  Never mind whether the spinning wheel itself is going to apply some sort of force to the vehicle due to the fact you have a spinning object you are trying to bring to a stop or a non spinning object, still carrying weight from the vehicle that has no grip and is just sliding along the ice/aquaplaning/etc...

How the entire car reacts to one or more wheels saying "I just became useless as far as traction and steering" goes matters to computer systems on the car and how they will react.  Hence while modern cars have microprocessors that register that fact and prompt various other systems to react.

Have a nice day.
 
2013-03-24 02:58:38 PM  

Edgewood Dirk: Csb - I drive a plow truck. (Eip if you want a pic of what I drive) awd fwd rwd whatever. Hiw about you stay tge fark off the road and let us do our job?
That coffee that you need, or the 2 litres of milk is unimportant.
Unless someone is dying stay off the farking road. All you wanna be Dale Earnharts just makes our job that much slower and harder.

Tl; dr stay off the road and let highways do their job.


First of all, Thank you for what you do!  (seriously.)

However; some of us do need to go to work and staying at home is not an option if we would like to keep our jobs.  As much as I wanted to stay home this morning because it was snowing...the internets must be kept in working order and that's my job.
 
2013-03-24 03:01:29 PM  

ha-ha-guy: rohar: Why would it matter if it's snowing, raining or the zombie apocalypse?  Either the wheel has grip or it doesn't.  Kinda straight forward isn't it?

So let me get this straight, your argument is one a wheel loses traction, it stops mattering?  Never mind whether the spinning wheel itself is going to apply some sort of force to the vehicle due to the fact you have a spinning object you are trying to bring to a stop or a non spinning object, still carrying weight from the vehicle that has no grip and is just sliding along the ice/aquaplaning/etc...

How the entire car reacts to one or more wheels saying "I just became useless as far as traction and steering" goes matters to computer systems on the car and how they will react.  Hence while modern cars have microprocessors that register that fact and prompt various other systems to react.

Have a nice day.


No, not at all.  What I'm saying is that the reason for the wheel spin is immaterial.  Snow, mud, coolant leak that left a puddle of slippery antifreeze on the tarmac.  It's all immaterial.   What's important is that traction is lost at an impossible to preconceive level.

In these situations, Audi/ZF/Getrag systems do very well, however they have their limits as you pointed out.  About 80/20 is their limit on torque bias.  They do, however, react immediately and to the appropriate level below their limit.  This is the value in mechanical systems.  Haldex does much the same with their systems excluding those with a viscous center diff.  The difference is in the diffs.  Haldex ATBs max out at about 3/97 torque bias and react, immediately, to conditions.

Can you show me an electronic system that can do that?
 
2013-03-24 03:10:03 PM  
Where I live the AWD makes a difference, it is very hilly here and gets cold and icy. Even with just wet conditions it makes a difference in getting you going...  it is CORRECT that it doesn't help stopping.

One bummer of the AWD is that it sucks down some of the Miles Per Gallon; so, I am burning more fuel and getting worse mileage.  But I don't get stuck.  My car (not quite an SUV) generally works well for me. I will get another one next time. I do use all-year Mud/Snow rated tires. They seem to be satisfactory for my driving all year around. And for where I (like to) drive - some roads are AWD/4WD mandatory.

Yeah, I laugh at those shiny clean AWD/4WD vehicals who's owners would be shocked and afeared to drive it on some Forest Service road and get it dirty.

/A good solid coat of mud may actually help protect the paint - adds a layer of protection on top of the wax.
 
2013-03-24 03:13:50 PM  
Oh yeah, It would be nice if my AWD vehicle had an actual 4-LOW mode.
 
2013-03-24 03:29:41 PM  
4wd / AWD is all about getting going and keeping going, modern snow tires are about traction ..

Car and Driver did some tests on this with a couple 2wd and 4wd Benzs and Audis ..

Should be obvious tires make a bigger difference than 4wd/AWD when trying to stop ..

from C&D (full article) ..

"Braking: The picture changes when you stand on the whoa pedal, because with four-wheel anti-lock braking, all four contact patches are working regardless of the driveline setup. Better-biting tires generate more stopping force, and the weight of a 4wd system simply adds to the momentum that has to be stopped. So it comes as no surprise that 4wd tended to lengthen stops from 50 mph (by as much as 12 feet on the Audi and 18 feet on the Benz relative to the stock 2wd setup). Fitting winter tires shaved stopping distances substantially (by 44 to 64 feet in the case of the A6s, and by 22 to 37 feet on the E320s). Winter tires win this one handily. "
 
2013-03-24 03:42:58 PM  
AWD is the shiat. Especially if you have a car with multi mode power shifting AWD, and adjustable steering. Lexus, infinity (Nissan on a few too, not just the GTR), bmw, and a bunch of others have this. It sure does help corner. It's insane how much better with the right tires a good awd system is. It helps to not be a shiatty driver, but it does make a shiatty driver better too... unless of course you have a 600hp car and are a dumbass.

/I like to turn of traction control for a little skid too, depending on the location
 
2013-03-24 03:47:30 PM  

Jim_Callahan: AWD is better for traction, single-axle drives are better for efficiency, completely fixed differential (4WD) is better for power.


I talked to a couple of BLM rangers once about trucks.  They loved, just loved 2WD F150 pickup trucks.  Great great truck. goes anywhere you'd want to go, and unlike the 4WD units won't go where you do not want to go.  Plus you can stick a dead deer in the back.

They hated the Hummers homeland security forced on them.  First off, you cannot stick a dead deer in the back of a Hummer. The hummers wheel base is too wide for narrow dirt roads, One of them said he felt embarrassed driving them, 'yep just me, driving along in this fool thing wasting your tax dollars'.  And unfortunately management thinks a hummer will go places a 4WD F150 won't go.
 
2013-03-24 03:57:21 PM  
yeah way to fail on scientific rigor, reporter.  Without getting into full 4wd systems, there's still four combinations of AWD and tires you can make if you start with an AWD car, its non-AWD equivalent, summer tires, and winter tires.

AWD-Regular tires
AWD-Winter tires
Non-AWD-Regular tires
Non-AWD-Winter tires.

He's compared the first and the last, and that's all.  So the question is, what happens if you stick winter tires on an AWD car?  I dunno...
 
2013-03-24 03:59:41 PM  

Ishidan: yeah way to fail on scientific rigor, reporter.  Without getting into full 4wd systems, there's still four combinations of AWD and tires you can make if you start with an AWD car, its non-AWD equivalent, summer tires, and winter tires.

AWD-Regular tires
AWD-Winter tires
Non-AWD-Regular tires
Non-AWD-Winter tires.

He's compared the first and the last, and that's all.  So the question is, what happens if you stick winter tires on an AWD car?  I dunno...


...it's pretty awesome

i21.photobucket.com
 
2013-03-24 04:21:15 PM  

traylor: Yep, snow tires will do. Because snow tires are AWESOME.


Real snow tires--the studded kind--will increase the coefficient of friction between your tires and ice, something that AWD or 4WD can't do.
 
2013-03-24 04:52:59 PM  

gibbon1: Jim_Callahan: AWD is better for traction, single-axle drives are better for efficiency, completely fixed differential (4WD) is better for power.

I talked to a couple of BLM rangers once about trucks.  They loved, just loved 2WD F150 pickup trucks.  Great great truck. goes anywhere you'd want to go, and unlike the 4WD units won't go where you do not want to go.  Plus you can stick a dead deer in the back.

They hated the Hummers homeland security forced on them.  First off, you cannot stick a dead deer in the back of a Hummer. The hummers wheel base is too wide for narrow dirt roads, One of them said he felt embarrassed driving them, 'yep just me, driving along in this fool thing wasting your tax dollars'.  And unfortunately management thinks a hummer will go places a 4WD F150 won't go.


To be fair, the only place an F150 is really suited towards going to after about 4 years is the junkyard.  But I still take your point about a pickup being better than a hummer for most BLM uses.

/Former state employee
//Large fleet of Ford trucks
///cannot count the number of times I've heard the "knock of death" on some F*50 truck
 
2013-03-24 04:59:05 PM  

yukichigai: gibbon1: Jim_Callahan: AWD is better for traction, single-axle drives are better for efficiency, completely fixed differential (4WD) is better for power.

I talked to a couple of BLM rangers once about trucks.  They loved, just loved 2WD F150 pickup trucks.  Great great truck. goes anywhere you'd want to go, and unlike the 4WD units won't go where you do not want to go.  Plus you can stick a dead deer in the back.

They hated the Hummers homeland security forced on them.  First off, you cannot stick a dead deer in the back of a Hummer. The hummers wheel base is too wide for narrow dirt roads, One of them said he felt embarrassed driving them, 'yep just me, driving along in this fool thing wasting your tax dollars'.  And unfortunately management thinks a hummer will go places a 4WD F150 won't go.

To be fair, the only place an F150 is really suited towards going to after about 4 years is the junkyard.  But I still take your point about a pickup being better than a hummer for most BLM uses.

/Former state employee
//Large fleet of Ford trucks
///cannot count the number of times I've heard the "knock of death" on some F*50 truck


My dad's 03 is still running strong and looking great.
 
2013-03-24 05:17:03 PM  
it's very important to understand that Four Wheel Drive is NOT All Wheel Drive

and that both have different characteristics on road surfaces.

4WD has locking differentials

AWD does not and also utilizes computer controlled wheel-spin/slip braking to help distribute even torque to each 4 of the wheels

The author is caught up on "handling" and then brings up "snow"  -   bullshiat, the two are like Oil and Water

AWD undeniably give better "overall" performance in snow and ice, however only with proper shoes on.  Not unlike the assclown wearing cowboy boots in the snow.  4WD in snow is also not an ideal choice as the locking front diff often encounters solid road on turning radius and will crunch up them spider gears.

The SUV's in the ditch...  anyone driving by them in fwd does have an "mechanical" advantage, they're just more in tune with the capability of their vehicles.  Trust me anyone that's gone AWD in snowshoes, would never go back to FWD or RWD by choice.

Nothing works better than good ole common sense, slow and steady wins he race.

/owns a luxury awd and has logged multiple 200+ mile snow/ice covered road trips, maintaining a 45 mph average.
 
2013-03-24 05:19:24 PM  
The SUV's in the ditch...  anyone driving by them in fwd does NOT have an "mechanical" advantage,
 
2013-03-24 05:47:59 PM  
Picture from Lancashire today.

www.allartnews.com
 
2013-03-24 05:50:14 PM  

Slutbucket: The SUV's in the ditch...  anyone driving by them in fwd does NOT have an "mechanical" advantage,


They're moving, the SUVs are not...I'd say they do.
 
2013-03-24 07:41:16 PM  
For all the people claiming a FWD with snows won't make it up a hill, wtf are you trying to drive up? Denali? I've never once in my life gotten stuck on a hill, and I've driven all over NY/New England for 15 years of winters.
 
2013-03-24 07:42:57 PM  

Publikwerks: Happy Hours: I've heard people proclaim that Subaru's are great in snow so much that I almost believe it, but I've never driven one. I'm not sure why that is other than I think they're all made with AWD, I don't believe they can defy the laws of physics though. If you're driving on a sheet of ice or there's very little friction you'd best slow down and avoid heavy braking.

You also can't floor it when the light turns green, I don't care how many wheels are fighting to gain traction. And be careful when cornering too.

My guess is that they are lower to the ground than alot of other AWDs.


Opposite.

There's "handling" AWD that you find in Mercedes/Audi/etc. and there's "go places awd". Subaru's AWD have more ground clearance and tend to be biased to act more like a 4x4 in high range.

Biases differ based on driveline and model, but that's why subaru awd tends to do well in snow.
 
2013-03-24 07:47:09 PM  

Ker_Thwap: My favorite winter hobby is counting the AWD/4WD cars off the side of the highway.  It's a nice slow speed tool, but does squat otherwise.


It also helps if you're moving between lanes and hit a 6" deep pile of slush. The other day I was merging from one highway to another and when I hit the slush I felt the AWD kick in hard, if I had been in a FWD car I probably would have spun into the wall.
 
2013-03-24 08:37:40 PM  
So, paid for by Les Schwab?
 
2013-03-24 08:38:05 PM  
Was sold on AWD back in HS.  Mom got a Subaru after dad died and it was quite useful in the mountains where we lived.

Later on I drove my Eagle Talon TSi AWD to SLC for skiing, on the way back there was a foot of snow on I-15 near St. George.  Powered through it with no problems while everyone else was pulled over putting on chains.

My current ride:

www.automotiveaddicts.com

Modded to give me 263 whp. :)
 
2013-03-24 09:17:02 PM  
My Audi S4 Avant Quattro FTW!

sphotos-b.xx.fbcdn.net
 
2013-03-24 09:21:47 PM  
AWD: Yes.  Snow Tires: Not Exactly.

i1240.photobucket.com">
 
2013-03-24 09:48:14 PM  

The Muthaship: AWD: Yes.  Snow Tires: Not Exactly.

[i1240.photobucket.com image 850x637]">


drooooooooooooooooooooooooool
 
2013-03-24 09:54:00 PM  

Girion47: The Muthaship: AWD: Yes.  Snow Tires: Not Exactly.

[i1240.photobucket.com image 850x637]">

drooooooooooooooooooooooooool


Love yours, too.
 
2013-03-24 10:09:17 PM  
AWD has its advantages and disadvantages.  I have had all three drive configurations and prefer them in this order: RWD, AWD, FWD.  One of my current rides is a Subaru legacy spec b.  Whether due to the tires (Potenza RE-11), or the AWD, the thing grips the road like a hooker grabbing her $20 bill.  Around corners its great.  At some other things, not so much.  I cant do donuts in it worth a damn.  It wont smoke the tires on launch no matter how hard I try and is nearly impossible to launch well.  The engine pretty much always bogs if you try to come off the line quickly.
 
2013-03-24 10:42:14 PM  

Ima4nic8or: AWD has its advantages and disadvantages.  I have had all three drive configurations and prefer them in this order: RWD, AWD, FWD.  One of my current rides is a Subaru legacy spec b.  Whether due to the tires (Potenza RE-11), or the AWD, the thing grips the road like a hooker grabbing her $20 bill.  Around corners its great.  At some other things, not so much.  I cant do donuts in it worth a damn.  It wont smoke the tires on launch no matter how hard I try and is nearly impossible to launch well.  The engine pretty much always bogs if you try to come off the line quickly.


You need to learn how to use that Spec B properly ... it should do donuts beautifully if done right ... I loved my WRX and it would do axis spins all night long.

Also, launching an AWD car isn't about revving and dropping the clutch, you need to use your clutch pedal to get motive force AND not bog the engine.  It's something you can improve on and never worry about how to launch an AWD car (if done right, your 60 foots will be faster than even the best RWD cars).
 
2013-03-24 11:20:16 PM  
Safety factors involved in driving in snowy/icy conditions, ranked in order of importance:

1) The skill of the driver behind you
2) The tires on the car behind you
3) The number of wheels driven on the car behind you
  .
  .
  .
69,105) Your skill as a driver
69,106) Your tires
69,107) The number of wheels driven on your car

Any questions?
 
2013-03-25 01:47:44 AM  

Man On Pink Corner: Safety factors involved in driving in snowy/icy conditions, ranked in order of importance:

1) The skill of the driver behind you
2) The tires on the car behind you
3) The number of wheels driven on the car behind you

  .
69,105) Your skill as a driver
69,106) Your tires
69,107) The number of wheels driven on your car

Any questions?


0) Whether the driver behind/next to you is even paying attention.

Friend of mine on a rainy morning on HWY17 came around a downward corner and there was stopped traffic, which on that road is bad, cause there are no shoulders.  But he braked hard pumping his brakes and for a second thought, yeah I got this, before he got a glance at the lady in the Quaalude next to him and was like, nope I ain't got this, right before she spun into him.

Two things.

No AWD is not 4WD.  AWD is good for road surfaces with uneven traction at speed. 4WD is good for uneven or slippery surfaces at low speed.  2WD is just fine for puttering aroind on good roads. 2WD with a limited slip differential is a good way to die.
 
2013-03-25 07:41:15 AM  

Kimpak: QFT!  Its hard to find a decent new car with a proper manual.  Flappy paddles do not count.  I miss my jeep, but it became too expensive to feed.


I love my manual FJ, smoothest manual transmission I've ever driven and I can go anywhere any time. Best non AWD vehicle I ever had in the snow, 86 Fiero. It was RWD but the engine was essentially right on top of the rear axle.
 
2013-03-25 08:17:15 AM  

yukichigai: To be fair, the only place an F150 is really suited towards going to after about 4 years is the junkyard.  But I still take your point about a pickup being better than a hummer for most BLM uses.


My '96 F150 is doing just fine.  It does go to the junkyard...but only to haul junk to it.  Its been one of the most solid vehicles I've owned.
 
2013-03-25 02:39:00 PM  
Can we all at least agree that people who don't clean the snow off their cars before going on the highway are jerks?
 
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