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4WD and AWD systems explained

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  • tincup47tincup47 Posts: 1,508
    The instructors, although Camel Trophy veterans, spend their time off-roading in the US now. Two of them had air lockers on their D90's. They had no problems with them, they just thought the recovery tools (which you seem to already have) and winch were a better investment.
  • bwhbwh Posts: 76
    So what does an ARB set-up cost per axle? They are correct because lockers will not get you out of situations where you need a winch. They may help keep you out, most of the time, but when it happens, the winch is the ticket. That is what makes it good advice in my eyes.

    The only other point I was trying to illustrate was that most folks do not have a Rover or a G-wagen. So adding an air locker to most regular 4x4s is a terrific enhancement, more so that on a Rover because its capabilities already exceed most 4x4s.

    Naturally having it all, lockers and the winch, is the real ticket.
  • hengheng Posts: 411
    But they can be pricey and since I don't do a lot of off-roading (only in and out of my property so-far) I don't want to mount it on the vehicle. Also I may need to pull my vehicle from the rear so I'm thinking of a winch that I leave inside and hook it to the tow hooks when needed.

    How much and is the unmounted method feasible.
  • bblahabblaha Posts: 329
    If you don't expect to get yourself into difficult situations alot, you probably would be content with just a comealong (usually cost around $50).
  • tincup47tincup47 Posts: 1,508
    Has winches that mount to a trailer receiver hitch, and there are front receivers available for some SUV's. ARB lockers are about $700 without the compressor. Compressor runs about $300.
  • hengheng Posts: 411
    It only has about 25 ft of cable on it which is way too short for those sticky situations. But it is better than nothing. Would have to pack some extra chain with it.

    Didn't have it with me when I got stuck. (poor planning) I will pack it in the truck.

    This is a good line of discussion. It transcends whether you push a button or not to get 4WD and how much better LSDs are over open diffs. When the going gets tough, you either get out the winch or you engage the locking diffs (you still may need the winch).

    From tincups post, it sounds like $1,000 to get the air locker and compressor installed (ouch!). Good winches are probably $500 right? I'll continue to mull this over.

    The 'riding on the beach' topic also has some good discussion on when the going gets tough.
  • hengheng Posts: 411
    just checked some web sites. For all but the light duty models you are talking close to $1,000 for a winch.
  • gluizgluiz Posts: 17
    Don't forget that you usually need a winch mount also - this can be a whole front bumper + brush guard. Also note that this will most likely interfere with airbags if you have them. Receiver mounted winches are great for portability but the drawback is that you have to carry them along in the vehicle. You can get extension cables (75') instead of chains.
  • hung0820hung0820 Posts: 426
    My Santa Fe!
    The manufacture said it was a Full-Time 4WD and this site said it was a Full-Time AWD. My Santa Fe have a 60% of torque in the "Front" and 40% of torque in the "Rear". What do you think about this 4WD or AWD suppose to be?
  • tincup47tincup47 Posts: 1,508
    It is AWD.
  • ateixeiraateixeira Posts: 72,587
    I tried to look this up earlier, but little info is available about the Santa Fe's AWD system. Anyone find a better source?

    -juice
  • hung0820hung0820 Posts: 426
    I don't know if the Sante Fe have the low-range or not? So like you says! If the Santa Fe have the low-range then is a Full-Time 4WD and if it does not have low-range then is a Full-Time AWD. Is this right! Does anyone know if the Santa Fe have a low-range or not? I can not tell when driving my Santa Fe. How can I tell the different between low-range or not?
  • paisanpaisan Posts: 21,181
    Santafe does not have a low range. IMHO it's AWD if there is less than 100% torque going to any given axle. Like the CRV and Escape put 100% FWD til it detects slippage, that is auto-engaging AWD IMHO.

    -mike
  • bblahabblaha Posts: 329
    ... that makes up its own terms, resulting in massive confusion amongs its consumers.

    The definitions I've tended to use are:
    AWD: 4 wheel drive without a transfer case. This also means no 4lo.
    4wd: Has a transfer case.
    If the TC includes a full time option, meaning it has some kind of a differential, then its "Full time 4wd".
    If it doesn't, then its just "Part time 4wd".
    The TC may include a reduction gear, in which case it has "4lo".

    These are all IMHO of course.
  • hengheng Posts: 411
    Do you have any selectable drive train mode of operation?

    If not, who cares? Certainly not you, because you don't have a choice.

    If you have a choice, all you need to know is whether any mode of operation is not for dry pavement.

    If you have lo-range, you have to have a button or switch or lever to activate it.

    So don't get hung up on what's it is called. Just know when each mode of operation should be and shouldn't be used (if you have a choice).
  • hung0820hung0820 Posts: 426
    I need to know if my Santa Fe is a 4WD or AWD because I need to put the right label (emblem) on my Santa Fe. My Santa Fe does not have any button to use at all. It drive just built into it and also I have the ABS & TCS as well. I know the system is working very good on snow, offroad, etc.. All I want to do it put the label in the car correctly.

    This AWD and 4WD is alway confuse and hard to explain to people. If someone pass by and ask which A/4WD system on the following car is work better: Santa Fe, Tribute, RAV4, Highlander, Forester, and Escape. Then how do we have a good answer for them. What do you think and what system is the best?
  • tincup47tincup47 Posts: 1,508
    The Santa Fe is either AWD or FWD depending on model purchased, it has no low range. The RAV4, Escape, Tribute, Honda CRV and Highlander are available in FWD or AWD versions. The Forester is only available in AWD. These vehicle's use different but similar ways to achieve AWD, but none of them are true 4WD vehicles with hi-lo range transfer cases. None of these vehicles are true off-road SUVs although they can do light off-roading. (But a lot of 2wd vehicles can also)
    What badge you put on it is as unimportant as what the different manufacturers marketing depts. call their AWD or 4WD systems. A name or badge never got someone out of a ditch.
  • Out of curiousity, how does the acura mdx system with a locking mechanism fare? Does it function offroad ( as in on the beach) comparably to a true 4wd system with a true 4WD low gear?
  • bwhbwh Posts: 76
    The Acura is designed for the road. It has no low range and limited clearance. For beach sand it should do OK. Reduce the tire pressure to increase your floatation, that would be your best bet. Remember the MDX is essentially a front drive mini-van with rear drive that kicks in when slip occurs. Car and Driver tested a bunch of vehicles in this class recently. I think the MDX came in first yet they considered it the least desirable off-road.
  • ateixeiraateixeira Posts: 72,587
    You can further categorize with AWD vehicles mentioned above into full-time and part-time.

    The Forester, RAV4, and Sante Fe are full-time, engaged all the time. I would label it AWD.

    The CR-V, MDX, and Escape are part-time. They are FWD until there is slippage. They engage automatically, but only on slippery surfaces. The Escape adds a manual engage button, but it's still not meant for dry conditions.

    Sound right?

    -juice
  • tonychrystonychrys Posts: 1,310
    People keep getting this stuff confused because of the marketing idiots.

    The two most popular configurations on non-truck-frame SUVs today are:

    AWD = Automatic Wheel Drive-- one axle normally until slippage occurs. Usually no 4-lo gear

    P-4WD = Permanent 4 Wheel Drive-- both axles driven all the time, with a near 50/50 torque split. Vehicles that come close to 80/20 split should really be called AWD. Usually no 4-lo gear.

    Of course an exception to both examples above are Jeep Grand Cherokees which can be configured with Select-trac, Quadra-trac and Quadra-drive, all with transfer cases and 4-lo.
  • paisanpaisan Posts: 21,181
    The Trooper to your list like the JGC, it has 2wd, fulltime 4wd and 4wd lo range. :)

    -mike
  • hengheng Posts: 411
    A quantitative response is not necessary, would it be closer to open diffs or locked diffs? Or probably somewhere in the middle depending on the setup?

    Think of open diffs as the easiest to get the vehicle stuck (low end of scale) and locked diffs as the hardest (high end). I'm not looking for any explanation of how LSDs work, just subjective views on how effective they are, particularly in situations where locked diffs would keep you going and LSDs would get you stuck.

    I'm sure any differences would become apparent only on non-paved surfaces, so lets start there.
  • ateixeiraateixeira Posts: 72,587
    I'm not an expert on the subject, but we could start by listing the types available:

    open/unmanaged
    limited-slip (viscous)
    limited-slip (torsen)
    open with traction control
    lockable

    -juice
  • bwhbwh Posts: 76
    "Somewhere in the middle depending on the setup" is pretty close. It really depends on how you intend to use it. For sand or mud a LS will be much better than an open diff and as effective as a locker in all but the deepest stuff. For rock crawling the LS is about worthless, a locker will prevail, the LS is closer to open in this case. To me it kind of depends on the vehicle you are considering. Most do not offer a locker period. Toyota is offering them on the TRD Tacomas, GM offers an auto locking rear in its new pickups, and Jeep offers a great system of auto lockers in the JGC. In cases like that get the locker. Where you have a LS as an option give some consideration to its use. Adding the LS will likely cost ~$400 or so. On a truck expected to go off road I would pass and put the money towards an ARB locker or some type of automatic rear locker, a Detroit Locker possibly.

    I guess that I really consider LS diffs to be better suited to powerful road cars rather than off-road machines. I just about all cases it is my opinion that a switchable locker, like an ARB, is the best option. The open diff gives better stability than a LS on slippery highways, and the locker is always there IF you need it. The flip side is a LS making your vehicle squirrley on slippery roads and slipping uselessly itself under duress off-road.
  • paisanpaisan Posts: 21,181
    I found the LSD on my trooper to work effectively on and off-road. Off road I actually thought it wasn't working, until I realized I needed to pre-load it a bit to get it to lockup. Onroad, the TOD system meant that the rear LSD didn't come into play often.

    -mike
  • hengheng Posts: 411
    That's what I thought. LSDs better than open diffs in the moderate stuff but useless in the tough stuff.

    Also came to the same conclusion that open diffs are OK on the open road with an ARB air locker switched on for the tough stuff. But since not having direct experience, I wanted input from others.

    Now all I have to do is find the considerable dough to cover the locker, compressor and installation. (compressor alone is $200)
  • paisanpaisan Posts: 21,181
    What do you drive again?

    -mike
  • hengheng Posts: 411
    Don't laugh guys. I, at least, can say I understand its limitations and that most other SUV owners don't.
  • paisanpaisan Posts: 21,181
    They aren't bad. A little narrow for my rather large butt :) I just wanted to make sure that you weren't one of the ones with like a CRV or Santa Fe, thinking you were gonna put a locker on it!

    -mike
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