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Toyota 4WD systems explained

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  • steverstever Viva Las CrucesPosts: 41,983
    that I should weigh in about my 20 years in Anchorage (the first two w/ a Bug and a RWD wagon) and my definitely average (at best) driving skills.

    But I won't - but I think IdahoDoug has pretty much nailed me :-)

    Steve
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    Minivan fan. Feel free to message or email me - stever@edmunds.com.

  • We are looking for an SUV and are concerned that the Highlanders AWD will give us trouble in sand. We go to the Outer Banks and the only way to get to the house is to drive on the beach. We borrowed a Tahoe last year and it was fine in 4WD Low (it almost got stuck in 4WD high). Any insight would be appreciated!
  • steverstever Viva Las CrucesPosts: 41,983
    We can't seem to keep the SUV for Beach Sand discussion going without it auto-archiving, but I've unfrozen it, so you may want to look in there too.



    Steve

    Host

    SUVs, Vans and Aftermarket & Accessories Message Boards

    Moderator
    Minivan fan. Feel free to message or email me - stever@edmunds.com.

  • Thanks! I read every post on the SUV for Beach Sand board. Not sure what to belive or do. What I didn't mention was that we already have an Outback but were concerned that we needed a "real" SVU to get around in sand. From the board I got the impression that just getting a bigger AWD (like Highlander or Pilot) wouldn't be an improvement.

    I just hate the Explorer, Jeep, 4Runner, etc. that we test drove.

    What's a guy to do?
  • wwestwwest Posts: 10,706
    Neither the HL nor its Lexus counterpart, the RX are REAL SUVs. They use three OPEN diff'ls, with a very WEAK VC across the center diff'l. As long as all wheels are on firm footing you will get even torque distribution all around.

    But the instant any wheel, or wheels, lose traction....GAME OVER !!!

    The "instant" torque distribution on encountering a low traction surface will be about 90/10 front to rear. The best we could measure on a 4 wheel dyno was 75/25 F/R and that was with artificially created circumstances which you will never encounter in real life.

    For true AWD look at the BMW X5, the ML320, or even the Chrysler T&C minivan. The T&C starts out like the HL & RX, 90/10 F/R torque distribution, but it is equipped with a VC that can really, quickly, buckle down and get the job done.
  • idahodougidahodoug Posts: 537
    So, were you able to get through the sand with your Subaru? If so, the Highlander would have similar capabilities.

    One consideration that may or may not be practical would be to lower your tire pressures for that section of the journey. I say this because it would seem more cost effective to buy what you want to drive on the 99.999% of applications not comprised of sand. Then adapt the vehicle to the sand during the half mile or whatever distance it is.

    Lowering your tire pressures to 15psi will perhaps triple a vehicle's traction in sand. It would simply be a minor inconvenience to carry a portable air pump, or air up in some other fashion when you left the house/sand portion. In sand, it's all about contact patch surface area and even a 2wd vehicle will comport itself quite well at these pressures.

    Regards,

    IdahoDoug
  • cmack4cmack4 Posts: 302
    I have a 2002 Bravada and it does a great job in the sand. Other AWD systems should work OK as well, but whatever system you would buy, I would highly recommend a rear locker!

    A lot of 4wheelers make the common mistake of using 4Lo in sand, and I would highly advise against it! Sure it can bail you out of deep sand conditions, but more often than not, it was the 4Lo (added torque) that dug the hole in the first place! 4Lo, if you have it, should be your last resort in sand.

    Air down your tires to between 15-18psi (20 if it's a lot of mixed on/off road) and stay out of ruts and you should be fine. I know my Bravada even did a nice job on dunes, so long as the breaking points didn't interfere with my clearance.
  • I'm in the market to replace my Navigator. Frankly, the only thing out there that interests me other than a new Nav would be the Sequoia, largely because of the Toyota reputation, and finally, it's "almost" big enough to contend. But, then I read the posts here, and this letter from Car & Driver Reader page, quote:

    "Officious" is too mild a word for the Toyota Sequoia's vehicle skid control system. Toyota may have uniquely designed the first system that is dangerous on dry pavement. In all-wheel-drive, where the VSC can be turned off only at low speeds, usual Midwest bumps such as train tracks tell the system to throttle back the accelerator. Ever change lanes with no power? And in rear-wheel drive, where the system always remains active, slight road irregularities continually activiate Big Brother, especially at low speeds. Ever turn right on red when a slight dip in the road kills the throttle as you try to power up and merge into the traffic flow? Cars backing up behind you with flashing headlights and blaring horns is a common experience in a Sequoia. It's a nightmare. John W. Riggs, St. Louis, Mo.

    Response from C & D: "It's the traction control chopping your p[ower, not the VSC, and we didn't experience the problem as often as you did. Ed.

    Car & Driver didn't experience it "as often"? That should make me feel better?

    I am hearing such horror stories about this truck, I am amazed at how human Toyota has become. Anybody else have personal experience with this phenomenon?
  • cliffy1cliffy1 Posts: 3,581
    I can get the traction control system to cut power if I want. The early ones has a bit more sensitive system as the newer ones but if you try hard enough, you can get the RPMs to drop. This is a good thing to happen of you are on ice. You want it to happen. If you are concerned about it happening, simply do what I have suggested about 30 times in this and the Sequoia topic and leave the thing in the 4WD mode.
  • intmed99intmed99 Posts: 485
    This "problem" is prevalent in ALL systems, from BMW to Mercedes to Toyota. It is the nature of the beast! There is no perfect system yet. I read once about a BMW X5 crashing on the side of the road because it's stability system startled the driver! Geez!

    You just have to KNOW that you have a stability/traction system. Don't be a fool and slam on the gas pedal to merge in traffic! You should not do that with a 4500 lbs SUV!

    The Navigator, if equipped with stability control, will have the same "trait". I think you can order a Navigator withOUT this system...i am not sure.

    For me, i have a '02 4Runner. I have not experienced the stability system at all during normal driving (in rain too). Only during off-roading that the system comes on.
  • Not very helpful, but thanks for caring. I only see knocks like this on the Tahoe (not a big surprise) and the Sequoia. Learning to just live with it isn't exactly what I was looking for. Just the fact that it has its own thread should tell me something I guess...
  • intmed99intmed99 Posts: 485
    I believe the reason for this thread is to explain the 4wd system of the 4Runner, Land Cruiser, and Sequoia. It has nothing to do with the "problem" of stability control.

    As you may know, the 4wd system of the Sequoia and 4Runner is pretty diverse...2wd, 4wd HI, 4wd LO, 4wd HI with center diff lock, and 4wd LO with center diff lock. Personally, i love this variety in my 4Runner! Not many other SUVs offer this variety! (in fact, can't think of one right now.)

    I don't think the Tahoe has a traction system similar to Sequoia, nor does it offer stability control.

    Like i said, all stability system will have this "problem." Ford just put the stability system on the '03 Navigator...basically, it is still in it's infancy! It may be worst than the other systems!!
  • What kind of situations might require me to lock the center differential in my landcruiser?
  • intmed99intmed99 Posts: 485
    Anytime that you are off-roading in uneven terrain or slippery conditions, you should lock the center differential. If you don't, VSC will kick in and DEPOWER you when you need power the most! It is a bit too late to lock the center diff when you are ALREADY stuck.

    Another benefit is that locking the center diff allows for a TRUE 50/50 power split between front and rear axles. Basically, there is no guessing by the computer where to send power...it is always 50/50. You will only need it in severe off-roading conditions. For example, when you have only ONE (or two wheels on ONE axle) wheel traction. In this situation, it is more efficient for the traction control system because 50% of power is direct at both axles no matter what. Seriously, i have never encountered such a condition. However, my center diff is almost always lock when off-roading (due to reasons in the first paragraph).

    Other than that, my center diff remains UNlock during daily driving.
  • ray_cray_c Posts: 36
    Hi,

    I'm planing on getting a 03 4Runner and would like to know the different between the full time 4wd and the part time 4wd in the new 03 4runner. And Can the part time 4wd be turn on at all time, even on dry flat surface?

    Thanks,

    Ray
  • So how do I lock the center differential on my Sequoia Ltd when in 4HI? Can it be done and is it the same procedure as when in 4LO.. i.e. transmission shifted to "L"? I just didn't happen to read my owner's manual thoroughly yet.. nor did I give it a try and experience that torquey engine.. ;)
  • intmed99intmed99 Posts: 485
    I don't think Sequoia can lock the center diff in 4-HI.
  • intmed99intmed99 Posts: 485
    Part-time 4wd modes in 4Runner: 2wd, 4wd HI, 4wd LO. You can use 4wd on ANY surface (e.g. dry land)

    Full-time 4wd modes in 4Runner: 4wd Hi and 4wd LO.
  • nippononlynippononly SF Bay AreaPosts: 12,695
    and current Sequoia can only lock center diff in 4LO.

    Only difference between 4WD systems controls in new Runner V-6 and V-8 is that on the V-6 it can be switched to 2WD if you want.

    2013 Civic SI, 2009 Outback Sport 5-spd (stick)

  • intmed99intmed99 Posts: 485
    Are you sure that the '03 4runner can ONLY lock the center diff in 4-LO??? That kinda suck! Many times i want VSC to be off in 4-HI.

    Oh well, i guess it is still plenty capable.
  • ray_cray_c Posts: 36
    So there is no different between the two in function wise. It justs that the V-8 (full time 4WD) has it on all the time and won’t allow you to switch it off. I wonder why they do that?
  • intmed99intmed99 Posts: 485
    Yes, both do the same function, except that the "part-time" system will save you $$$$ with the 2wd mode.

    The V8-option carries the 5-speed auto tranny, which is seen in Lexus and Toyota Land cruiser. Therefore, all 4Runners with the V8 option will have the same powertrain as the LC and Lexus. This saves money for Toyota.
  • cliffy1cliffy1 Posts: 3,581
    There is actually one other difference and that is that the V8 models have a torsen center differential. This keeps some power available both front and back, while the 2002 is an "open" differential that will route all power front or rear. Both will get power where it is needed but the torsen works better in more extreme situations.

    With either, you can lock the center in any 4WD mode.
  • intmed99intmed99 Posts: 485
    In the '02, when i put it in 4wd (center UNlock), is it 50/50 split?? What happens when slippage occurs?? Does it send power to the axle with traction??

    Thanks.
  • intmed99intmed99 Posts: 485
    You will have the center diff lock anyway...thus, both '02 and '03 system will be equal then.
  • cliffy1cliffy1 Posts: 3,581
    Yes, in the 2002 in 4WD with center unlocked, you have a true 50/50 power split IF traction is equal at all wheels.
  • cliffy1cliffy1 Posts: 3,581
    With the new torsen center, the chances of needing to lock the center are not as great. Your worst case is 29/71 (front to rear with front slipping) or 53/47 with the rear slipping. This is without locking the center where you have a true 50/50.
  • Anyone know/understand the '03 Runner's 4wd system enough to say if there is any side to side traction control? Does the torsen diff accomplish this even a little? If this has been addressed, please let me know where I can find it and forgive me for not keeping up.
  • intmed99intmed99 Posts: 485
    Toyota's ATRAC (active traction control system) manages the side-to-side traction. Torsen only manages the front-to-rear transfer of torque. The 4Runner/TLC/etc. can perform ONE-WHEEL TRACTION.

    Answer to your question: yes.
  • intmed99intmed99 Posts: 485
    This is from FOURWHEELER magazine (an off-roading magazine):


    http://www.fourwheeler.com/editorial/article.jsp?viewtype=text&id=20998


    I think they really like it!

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