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4WD & AWD systems explained

1377 messages,  Last post on Dec 05, 2009 at 1:47 PM

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What is this discussion about? Chevrolet Suburban, Jeep Grand Cherokee, Subaru Outback, Ford Explorer, Nissan Pathfinder, GMC Envoy, Performance Mods, Tires, Suspension, Transmission, Truck, SUV

#51 of 1377 Drew - by loboy Feb 12, 2001 (3:59 pm)
Very informative with the descriptions of different types of 4WD systems. I agree that many people (myself for one) are misusing the 4WD/AWD misnomer. Now my question: Are the Pathfinder/QX4 systems classified as AUTO 4WD, similar to the Trooper above, and not AWD, since they have low range gearing? Thanks
#52 of 1377 loboy by drew_ Feb 12, 2001 (4:39 pm)
Absolutely! You got it. The QX4/Pathfinder LE's system is auto 4WD. Nissan calls it "All-mode 4WD".
#53 of 1377 Toyota 4Runner by woodyr1 Feb 13, 2001 (11:27 am)
Drew:   I own a Nissan Pathfinder with a part-time 4 wheel drive system. A direct mechanical link exists to engage the transfer case and operate the front drive shaft.   I am considering the purchase of a replacement vehicle and am looking at a Toyota 4Runner. The 2000 model (SR5) has a floor lever, like my Nissan, which locks in the front drive shaft almost instantly upon engagement, a part time system. The 2001 models have 'one touch 4 wd', which works through a centre differential and apparently allows one to drive in any road condition in 4 wd, without damage to tires or mechanical drive components.   I live in central British Columbia amongst the mountains and valleys, and engage 4 wd, as conditions warrant (snow, ice, etc). I drove a 2001 4Runner, and noticed a delay from when the one-touch 4 wd button was pressed until the 4 wd icon illuminated on the dash. Do you know what mechanical processes exist to account for this delay? My present vehicle actuates 4 wd almost instantly as engaging the floor lever. I like the advanced features of the 2001 Runner, such as traction and skid control, but am concerned that the 'lag' in engaging 4 wd may present a delay in obtaining traction when needed. With a centre differential, leaving the 4 wd engaged would not cause any wear problems, but the increased fuel consumption and loss of power may be noticeable. I have an opportunity to buy a 2000 4Runner SR5, which may be more suitable to my environment.   Thanks
#54 of 1377 by ateixeira Feb 13, 2001 (11:36 am)
Why not take a look at the Highlander? It has more room and a lower price, plus permanent AWD. No worries, no buttons, 225hp, and better gas mileage.   If you don't need the low range or ladder frame, it looked pretty nice at the auto show I went to.   -juice
#55 of 1377 Wes by drew_ Feb 13, 2001 (1:40 pm)
Nice to hear from another BC'er. AFAIK, the one touch 4WD engages the front prop shaft in exactly the same way as your Pathfinder, except that there are more electronics involved to actually engage the mechanics. Do you recall if the wheels were turned, or how quickly you were going at the time? I know that it does not necessarily engage until certain parameters are met (to prevent damage/excessive wear and tear to the system).   Personally, I would recommend that you leave the system in 4WD mode at all times. If there is any fuel economy difference it will be negligable, and you will have twice the amount of usable traction than in 2WD mode at all times. As such, in any emergency situation, VSC may not have to intervene as early or as forcefully. FWIW, Consumer Reports ran their Jeep Grand Cherokee Laredo with SelecTrac 4WD (similar to the Toyota's system) in both 2WD and 4WD full-time modes and found no difference in fuel economy. They recommended leaving the system in the latter mode at all times since it helped to stabilise handling. As for loss of power, this shouldn't be the case at all since 4WD simply redistributes the power from the 2 rear drive wheels to all four wheels. As a result, you also get more even tire wear.   To see a technical view of why full-time/permanent AWD/4WD is better than 2WD, read the following links: http://www.4x4abc.com/4WD101/tractionturn2.html http://www.4x4abc.com/4WD101/tractionturn4.html   Hope this helps! Any questions are welcome, of course.
#56 of 1377 juice by drew_ Feb 13, 2001 (1:42 pm)
Good suggestion, but I have a feeling Wes will want to take the vehicle off-road now and then The 4Runner would definitely seem more at home in central BC than the Highlander (though it's also a good choice). In snow though, the 4Runner would definitely have the advantage.   Drew Host Vans, SUVs, and Aftermarket and Accessories message boards
#57 of 1377 by ateixeira Feb 13, 2001 (2:10 pm)
You mean the Highlander just for snow, right?   -juice
#58 of 1377 by drew_ Feb 13, 2001 (3:40 pm)
Huh? No I mean the 4Runner for snow. With its greater ground clearance, and permanent 4WD system + stability control, it should be better than the H.L.   Drew Host Vans, SUVs, and Aftermarket and Accessories message boards
#59 of 1377 2001 4Runner 4wd system by woodyr1 Feb 13, 2001 (4:02 pm)
Hi Drew:   Thanks for the information. To answer your question, I was going straight at about 30 kmh, when I pressed the one-touch 4 wd button. The icon on the dash flashed a few times, then became solidly illuminated. It was fully in 4 wd at this time.   I appreciate your input, as in winter conditions, leaving it in 4wd will be of benefit. With all the electronics and speed sensors etc. do your forsee expenses with servicing, or reliability? I understand that the system is covered by the 5 year/80,000 km power train warranty.   Thanks   Wes
#60 of 1377 Wes by drew_ Feb 13, 2001 (4:23 pm)
What you describes actually seems normal to me. I recall the same behaviour when I test drove the '99 4Runner Limited about 3 years ago (back then only the Limited version had the full-time 4WD system).   With the 4Runner's excellent track record in mind, I do not forsee any problems with leaving the vehicle in 4WD mode all year around. Actually, a friend of mine has a '99 4Runner Limited (bought it brand new in late 1998 ) that is in 4WD mode all year around, and I have yet to hear him mentioning anything regarding reliability problems, or the lack of power/loss of fuel economy with his truck.   I hope this helps in your decision. Please keep us updated. Happy hunting! Drew Host Vans, SUVs, and Aftermarket and Accessories message boards

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