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Toyota 4WD systems explained

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Comments

  • russlarussla Posts: 74
    We are in violent agreement, except about the auto locking.

    How does one answer the question? "What's the difference between Full time and All wheel drive?"

    I think there are at least 3 decent answers that are defendable in a debate. And some others less so.

    a. there is none, AWD systems that drive all wheels are by definition full time systems because you can use them on the road it's just branding and marketing.

    b. Full time systems usually have a selectable Transfer case lever/switch and a low range, AWD is single speed only, either can be auto locking

    c. Full time systems are 50/50 or close to torque split and AWD can be more biased to one axle all the way to 100/0. either can be auto locking or not

    D. AWD systems are car based and autolocking and Full time systems are not.

    My preference is to use the answer C, others may choose B.

    But C is a gray definition, because there is not a clear definitive point between AWD and Full time using this answer. 50/50 is definitely full time, and 90/10 is AWD by that definition, but where it changes is pure speculation.

    Using C also lets me lump the on-demand systems (honda crv) with a 100/0 bias until slip into the AWD category,

    Have a great day
  • jefferjeffer Posts: 31
    Thanks all for this great discussion. It was starting to get clear, right before it got murky again. And to throw a little more fuel on the fire, a few years back I did some research on AWD cars. I found they made another distinction. Audi calls their system permanent AWD in that, if I remember correctly, they apply torque to all of the wheels all of the time, but of course adjust the split according to different conditions. The other term that was used was Part-time AWD which applied all of the drive to the front and then split it under certain conditions. The part-time AWD also, again if I 'member correctly, disengaged after you reached certain speeds, around 18mph I believe. So I kind of like that distinction coz it's easy to think of it in those terms. Also another factor of these 2 AWD types is that there was no user intervention required. I hope I'm remembering this all correctly, if not please don't shoot me. ;)
    Jeffer
  • 2toyotas2toyotas Posts: 104
    Here is one to complicate things. The Jeep Grand Cherokee has a new Quadra Drive 2 system, in normal driving it sends all power to the rear wheels but can instantly send power to the front or any one wheel. It has a Low range, and can do heavy Off-Roading. It is definitely 4WD not AWD. That is why I like to refer to AWD as not having a Low Range. A few others are Chevy Tahoe-Yukon, Ford Expedition, and Nissan Armada. All when in Auto 4WD send up to 80 or 90% of the power to the rear until there is wheel slip, but all have Low Range and can be locked in 4Hi. I think they try to intentionally confuse people, because most people don't know what they really have. My favorite is a system that sends power to all wheels all the time. I hope Toyota never changes.
  • jefferjeffer Posts: 31
    I need to correct my last post. Actually after thinking about it I believe the 2 forms of AWD were called Full-Time AWD which was actually FWD until a shift in torque was needed or Permanent AWD which put power to all of the wheels all the time. In the permanent I believe the split could go up to 90/10 but that I'd have to check on.
  • russlarussla Posts: 74
    I understand the new systems in the 05 grands to be full time systems, they wouldn't be AWD by my classification. It is my understanding that the torque split in both the single NV145/7 and the 245 are 48/52, if you look on the jeeps site, they have branded both as Full time systems.

    On the Quatra trac II systems the center diff autolocks with electronic clutches, on the Quadra drive system, they add electronic locking differentials. In normal going however this is a Full time system with power going to both axles.
  • russlarussla Posts: 74
    Bear with me if you will,

    the old VW Syncro vans had a VC, they were essentially RWD, and when there was slippage, the VC locked up and sent power to both axles. They didn't have a two speed transfer case. My 96 Jeep, even though it has a low gear, works the same way.

    why should the Syncro be called AWD, and my Jeep Full time? because it has a low range and a lever I can pull?

    Shouldn't the name be somewhat reflective of how the system acts? that's how we describe transmissions. (manual, automatic, manumatic)

    the number of gears is really unrelated to the how it works. But the how it works should frame the description.

    so I would call the auto torque shifting AWD systems that migrate the torque from front to rear during turns.
    "Yaw Activated, Acceleration Biased Torque Distributed, All Wheel Drive"

    or Yaabtdawd for short, since their initial bias is 0/100

    unless of course they were normally full time, with a 50/50 split, then they would be called
    a FULL TIME system with YAABTD

    (said with my tongue in my cheek)

    later...
  • jefferjeffer Posts: 31
    In my mind if you are sending all of the power to the rear you could be asking for trouble. Because, as we all know, rear wheel drive is much more prone to spinning out on a curve. Even if they start sending power to the front it may be too late. Once you start slipping you may not recover. Also going up a slippery slope the same thing could happen. Last winter I was going up a steep hill in my FWD Maxima. I was not able to get a good headstart due to this stupid center island they put in. I got half-way up the hill and started to slide backwards. I kept the front wheels spinning but the car just kept sliding backwards - very disconcerting. So I got back down to the bottom of the hill and went around the stupid island on the wrong side which gave me enough momentum that I was able to keep going all the way to the top. The moral of the story is that once you loose traction or momentum you may never get it back. So to me, the best traction is when you have power going to all 4 wheels, that is when all 4 wheels are on similar surface.
  • serranotserranot Posts: 113
    Since there seems to be no clear definition of these various 4wd/awd/full-time 4wd terms, why argue about it? Who cares what you call it? The fact that the manufacturers use some of these terms inconsistently leads me to the conclusion that it is better to describe the characteristics of the 4wd/awd system than trying to name it or label it.

    An amusing argument but pointless since there is no agreement.

    Regards,
    Tom
  • wwestwwest Posts: 10,706
    Rather a discussion...

    And out of discussions comes mutual agreement.

    Well, sometimes.

    Two consistencies...

    At least for on-road capable vehicles.

    1. AWD NEVER requires driver interaction.

    2. 4X4 does, ALWAYS.

    4WD seems to be used interchangably with AWD but is more consistently associated with the full-time mode of a 4X4 multi-mode system.
  • cgrcgr Posts: 2
    Based on what I've heard in this forum, I am making the following assumptions in my quest for a 2005 Tundra Double Cab:

    1. I do not need Part 4WD, as it will not really gain me much unless I am planning on frequent offroading use.

    2. Go with 2WD and the VSC/TRAC systems, as that will do more for me in the winter than 4WD on highway/adverse pavement surfaces.

    3. Knowing I will not be doing much (if any) intentional terrain stuff, I don't need the limited slip differential as it would really not gain me much anyway. While it wouldn't hurt to have it (because if something goes wrong with it, it will just revert back to open differential), having it opens me up to the possibility of having to fix it after it wears down (does this happen often with Toyotas?).

    Based on those assumptions and what I've also read elsewhere, it appears as though buying the part time 4WD and engaging for adverse pavement road conditions (snow, ice, rain) is not safe nor does it by me any real added 'traction' - only torque - as it:

    a) decreases turning maneuverability
    b) increases chances of unstable stopping due to lack of central differential - resulting in understeer / oversteer while also deactivating ABS system

    Are these assumptions correct?

    Based on a / b above, is this to say that engaging it in adverse road conditions, during highway use (e.g. a 20 minute commute to work) would be unsafe for both me and the mechanics of the truck (binding?)?

    The general feel of what I've read is that the answer is it is not really safe to use on ANY kind of pavement, but if I do decide to use it during pretty bad road conditions, to only do so when I am starting to get up and go, or going up a steep incline - but then turning it off once I get up to speed.

    Speaking of speed, is 50 MPH the max. speed I can engage 4WD? What are the max. speeds for 4WD hi and lo?

    One final thought...let 'pretend' like I've already got a truck on order from the factory with LSD and 4WD and have put a $500 good faith payment down, but could still eat (absorb) the $500 and change my order to only get a 2WD with the VSC/TRAC systems. What would you recommend me doing...?

    Lots of questions in this, I'll appreciate any answers:)

    Thanks!
  • russlarussla Posts: 74
    You have to decide on your priorities & planned use of the rig.

    for me..

    I'd rather have a part time rig than one with 2wd, but it rains a lot where I live, and I would be comfortable switching it in and out of part time. If I owned a boat, I'd want a part time rig too, if I went in the hills to camp, I'd want a part time rig over 2wd. Part time adds a lot more go traction. That opens up, or improves access to the things I would do with such a rig. your requirements may vary.

    I don't feel the concerns about part time you bring up are a significant safety or manuverablity issues, especially because when it's slippery, everyone's disadvantaged, but people with 4wd have better ablility to move forward. The systems aren't as fragile or unsafe as painted in your thread.

    Good luck with your decision

    PS, don't worry about top speed.
    In low range you're supposed to be going slow.
    in hi range, it will go faster than you should be going. (how's that for specifics)he he
  • nedzelnedzel Posts: 787
    There is absolutely no way I would get a 2WD pickup. I live where it snows. Pickups are heavy in front and light in back and therefore have poor traction if 2WD. If it snows where you live, I'd get 4WD, even if it is part-time 4WD.

    If conditions are bad enough that you have engaged part-time 4WD, then you don't want to be going 50 mph.
  • wwestwwest Posts: 10,706
    If you're going ~50MPH or more it can get a little hairy in a big hurry with all four wheels driving. Same can be true, but much worse, for FWD vehicles.

    At speed, cruising, on "dicy" roadbeds, it is definitely best to have only the rear wheels driving and the front wheels' "contact patch" dedicated solely to maintaining directional control.
  • lorryfanlorryfan Posts: 76
    I have a question:

    Am in the market to purcahse a new 4Runner, and I currently live in Arizona. In the next couple of the years, I will relocate the family to either VA or CT dependening on where my job takes me.

    Now, since it hardly snows in AZ, and I will be doing zero off-roading whilst in the desert, I would probaly never get a 4WD (whether it's part-time of full-time) . With the possibility of re-locating to the north east where it snows very often, am not sure if the 4Runner 2WD would be adequate for most driving conditions (i.e. snow, ice, sleet, rain etc...)

    All I want is to make sure my wife can drop off the kids at school during those snowy days and pick 'em up in the would be family vehicle.

    Can someone on this forum share more light on this question/scenario? I don't care about all the fancy marketing names and the power.....and maybe the glory of having a 4X4. Just a vehicle that is roomy enough for 4 and can take us from point A to point B - the 4Runner fits our budget nicely.

    Many thanks and I look forward to your responses.
  • wwestwwest Posts: 10,706
    what form of roadbed adversity your might encounter from one winter day to the next, or from one road mile to the next for that matter. But probably the worse condition your wife may have to content with is an ICE or packed snow covered downhill roadbed with a not just a few tight turns.

    Absent something to "bite" into the slippery and "hardened" roadbed surface, studded tires or snowchains, your wife should simply keep the kids home by a nice warm fire on those days.

    Back in the days when one or the other of us had to shuttle the kids to and from school each day I most often relied on a Ford E150 van which always wore summer tires but with snowchains installed when the roads were dicey.

    Some will tell you to get the multi-mode drive 4runner, 2WD, AWD/4WD, and 4X4 modes, and equip it with the best winter tires, not all-season, you can find. I have owned two Jeeps, an 85 and a 92, both with 2WD, 4WD and 4X4 modes. even with good winter tires I NEVER found it satisfactory to get up and going, and keep going to my final destination, in ANY drive mode absent the use of snowchains, in many cases all 4 snowchains.

    Many times it wasn't really the actual roadbed conditions that led me to the use of snowchains, but the many idiots out there trying to get somewhere with NO special traction capability at all.

    So I learned, that if in the end snowchains are the only answer anyway, I might as well run nice quiet and comfortable summer tires and then install the snowchains when greater traction was/is needed.

    So my current SUV, a MY2001 AWD RX300 has 1.5" wheel spacers all around, was upgraded to 17X8 wheel and tires, and in the wintertime I always have 2 sets of snowchains on board and at the ready. The RX300 as shipped has too little clearance between the rear tire and the strut to accept rear tire chains.
  • tcpoobtcpoob Posts: 30
    you and your wife will need the 4wd in Northeast where it snows and gets icy.
    i just switched from fwd sedan to 4wd 4runner v6 in Boston area, the diff is
    obvious in winter.
  • lorryfanlorryfan Posts: 76
    Thanks for your insight - wwest & tcpoob

    I was always leaning towards a 4WD, and you have made it easier since you guys have experienced the driving conditions live and colored....I appreciate the info.

    Thanks,
    lorryfan.
  • nedzelnedzel Posts: 787
    I live near Boston. You can get by with 2WD and snows. But I put snows on my 4WD 4Runner. I'd get 4WD. 2WD 4Runner seems pointless to me.
  • 2toyotas2toyotas Posts: 104
    Just curious, what brand of snow tires did you put on? I put on Bridgestone Blizzaks, and the truck performed incredible. The main difference being in stopping.
  • nedzelnedzel Posts: 787
    I've got Nokian Hakkepelittas (sp?). Braking and turning in the snow improved dramatically over the OEM Dunlops -- the original tires were downright scary in the snow.

    My main complaint about the Nokians is that they are very noisy.
  • frankvhfrankvh Posts: 1
    I've read a whole bunch of (very informative) postings in this forum - thank you all - but I have one thing I still don't understand.

    In Toyota Canada's literature for the 2005 4Runners, they state that the (full-time 4WD) V8 runner has a 2-speed transfer case and a centre differential lock. They do *not* list these 2 features for the (part-time 4WD) V6 runner. I'm more interested in the V6 runner due to better fuel economy. Any idea why Toyota wouldn't list the V6's as having the 2-speed transfer case & locking centre diff? Do they indeed really not have them?
  • tcpoobtcpoob Posts: 30
    i've got the 2005 v6 4runner sr5 4wd. and it should have the same
    config of xfer case etc you're interested in. yes it does have 2 spd xfer
    case - it's got to have it as it's a low range. and yes it has torsen locking
    center diff. hope this helps.
  • jr35jr35 Posts: 2
    I've lived in the Northeast all my life, CT, Boston, upstate NY. I've had 4wd, rear, front and a Subaru. You could get by with any car if you have patience. They do plow up there. When I lived there I skied a few times a month and whitewater kayaked 9 months out of the year. All of this included driving in rain, snow, and ice often.
    The rear wheel drive is no good. I've done it though. 3 feet, 90 Mustang with sandbags in the trunk.
    Front wheel with traction control on a 94 Volvo. Still okay, but skid around a bunch.
    4wd Jeep GC, was really helpful most of the time, but most conditions are mixed. You rarely have all snow or all ice. Most of the time it's snow under one side of your car, ice, water or dry pavement under the other. So 4wd engaged is not always good and when it's off you're stuck with 2wd rear with no weight over the back tires.
    My best car up there was a Subaru. It was always helpful in mixed conditions, handled like a sports car on dry pavement. I could go places we couldn't get the four wheel drive cars into. I assume the differential was the reason.
    I can honestly say that the Subaru saved me multiple times. I cannot say that about any other system I have had. Audi also has a great system.

    So, in the Northeast any car can work and they do. But there's a reason it's the Subaru capital of the US.

    But I need a bed so that's why I'm buying a truck. If I didn't have to and I was only driving the kids around and daily chores, I'd be buying a Sub. Better mpg, safety and comfort.

    I hope that wasn't too long.
    Cheers.
  • wwestwwest Posts: 10,706
    multiple times....

    You're still here, so obviously the other vehicles performed much better than the subaru, you just never had cause to notice as you did in the subaru. Where you pushing the Subby too hard because you had AWD??

    Just what was it that happened, apparently repeatedly, in the Subaru that never happened in the other vehicles?
  • kwiktoykwiktoy Posts: 1
    Plan to order 2 wheel access tacoma with vsc/trac. Heard it might not be available. Is this true. Also, does any of the cd players play mp3?
  • jnm1jnm1 Posts: 7
    Thanks for taking the time to answer our questions. You will have to forgive people like me who don't know any better as far as my question is concerned. I bought a 05 SR5 2WD Tundra and might be moving to Neb with snow..is there any way I can keep this truck and upgrade to 4WD without trading it in for the other model...or would that be my better option given a choice? Appriciate the help! Jen :confuse:
  • stickguystickguy Posts: 14,716
    It would cost way more to upgrade your truck (it's theoretically possible, but not anything ligical). If you really think you need 4WD, bite the bullet and trade it in.

    2013 Acura RDX (wife's), 2007 Volvo S40 (daughter stole that one), and 2000 Acura TL (formerly son's, now mine again)

  • nedzelnedzel Posts: 787
    The cheapest way to get 4WD would be to trade it in.
  • eaglegeagleg Posts: 87
    Buy Bridgestone Blizzak snow tires.I've driven a Chevy C1500 for 13 years and my wife drives a Mustang with them in Wisconsin and we've never had any problems in the winter.Great alternative for winter driving.
  • I have a 2000 Tundra 2WD with 40K on the Goodyears. I have had no weather related issues at all with this truck here in Buffalo, NY.
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