4WD vs AWD

[debc9672]

I'm considering buying a new Chrevrolet - either the Equinox or Trailblazer. What do I need to consider for 4WD vs AWD? I don't do any off roading but I do drive in snow occassionally and have always had a 4WD vehicle. Will the AWD Equinox be ok for me in a few inches of snow?

[njyahoo]

AWD will work perfect for you. A common misconception is the idea that AWD means that all the wheels are being powered at all times. Actually just the rear tires are being powered. There is a detector in the transfer case and the front/rear differentials that sense when one or more tires are loosing traction. The transfer case/differentials automatically transfer power to the tires that still have grip. As soon as conditions are back to normal the rear tires take over again. There are no buttons to push or selector for 2 wheel/4 wheel because the system is on all the time. 4WD is user selectable and can have similar components. The difference is that the vehicle is always in 2 Wheel unless 4 wheel is selected by the driver. Hope this helps clear up any confusion.

[TRD2000]

what about "full time 4WD" as used in the 80 series land cruisers for example?
STI have an electronically manipulated viscous coupling centre diff that allows the driver to dial in from 70/30 to 50/50 torque distribution but the standard subies are stuck at around 60/40 standard.. but they are AWD.
also some AWD cars actually drive front wheels not back.
there's a bit more to it.

[njyahoo]

Originally Posted by TRD2000

what about "full time 4WD" as used in the 80 series land cruisers for example?
...also some AWD cars actually drive front wheels not back.
there's a bit more to it.

I was trying to be as general as possible...you know KISS, Keep It Simple Stupid. Feel free to expound as much as you desire. Ask a generic question, get a generic answer.

[TRD2000]

my point is i think the line between AWD and $wd has been marred by car marketers, AWD became a catch phrase and so suddenly all these cars that were actually 4WD were said to be AWD, which just confuses people... hell i'm confused!

[lakerfan1784]

4WD has driver selectable ranges, such as 2HI, 4HI, etc. AWD is permanent and computer controlled, with no ability of the driver to force only 2 wheels to spin. my brothers astro van has AWD, and the torque split front to back is 20:80, or somthing like that, and when slip is detected, the center differential splits the torque up to 50:50

[TRD2000]

yeah but the Nissan GTR is 4WD and it is computer operated with no selectable hi low etc.

i think it has to do with whether it runs a centre diff or a direct power take off to the other wheels.

[Jethro]

I use both. A4WD for on dirt roads. and if manuvering around with a big load I'll lock it in 4WD. Driving in 4WD and be tough on it when making sharp turns. A4WD is smoother and don't know its even engaged.

[TRD2000]

ummmm... that doesn't REALLY determine whether it is 4WD or AWD.

see AWD cars like the subaru ALWAYS drive four wheels. so i guess they are "locked" that way. but not necessarily 50/50

4wd cars can either be user selected or computer controlled to disengage. so "AWD" mode just leaves it up to the computer what you need. "locked" means that it permanently engages 4 wheels.

SOUNDS like you drive a 4WD.

[igor@af]

Here is my take on this :

AWD example - Subaru Impreza WRX - all 4 wheels powered at all times - same amount of torque.
4WD example - Nissan Skyline GT-R - computer controls torque distribution between front and rear based on traction.

[TRD2000]

pretty good... except AWD cars aren't necessarily same amount of torque. it can be split according to conditions, and it can be locked... like the STI. where you can dial in from 70/30 to 50/50.

4wd actually tends to be more locked as far as torque goes than AWD cause they run like a clutch setup rather than a diff setup.

[miker142]

here is my two cents - AWD powers the front wheels normally on an equinox, the back wheel kick in if there is slipage. Interestingly, the weight difference between a 2 wheel drive equinox and awd is about 90lbs. Because of this light transfer case unit, only a maximum of 30 percent of torque can be diverted to rear wheels. Living in Buffalo, and use to 4 wheel drives that concerned me. Here, "off road" can mean City streets with Lake Erie lake effect snows. I wondered if equinox would have enough capablity to handle those conditions. I also saw in an engineering document that the awd unit had a thermal protection capablity leading me to believe that it became too taxed it would quit for a while.
That said, I decided on a trailblazer to replace my blazer. My blazer and trailblazer both have awd. I have found it useful in change road conditions and light snows. Anything beyond that is an annoyance as the vehicle slips around a bit before awd engages.

[TRD2000]

thats one sort... it doesn't apply to all, sounds similar to the type honda use. definately not restricted to fwd then awd, some are naturally RWD oriented. like Subaru.