Quote:
Originally Posted by Inv4drZm
4WD might be better but 2wd won't prevent you from driving to work in the snow. Even if roads are ungraded trucks have more than enough clearance in either configuration.
You only have to lose traction with 2 tires in an unlocked differential 4wd for it to become useless.
4wd for an experienced driver in the snow, at best, gets you to your destination faster as long as traffic conditions/congestion allow. Which it never does in stop and go traffic.
4wd for an inexperienced driver in the snow has the potential to create a worse accident due to the extra acceleration grip and false confidence under acceleration.
|
Quote:
Originally Posted by swampdodo
I can believe that. But this doesn't not apply to all 4x4 vehicles. Some vehicles automatically disengage ABS when in at least one 4x4 mode...while other leave it engaged (some off roaders actually hate this)...and can actually increase the stopping distance. So, as with all things...results may vary...
|
So I'll throw a little knowledge and experience in here to better reinforce these two points that I agree with.
-The majority of modern vehicles
do not fully disengage ABS/VSC/TRAC features in 4WD. Toyota is one of the quickest examples that comes to mind, the VSC OFF button doesn't actually fully disable the VSC system on many of the older Toyotas and on newer ones there is even an option for "Fully Disabled" by holding the button for something like 10 or 20sec (the owner's manual will tell you if your vehicle has that feature and how to make it work). Additionally the 4WD position does partially deactivate the various systems in the sense it increase the tolerances before it engages the further down the 4WD setting you go.
I remember one specific instance where my '04 V8 4WD in 4Lo, Center Diff Locked, 1st Gear it
still fought me with the A-TRAC/VSC functions when I went through a section of the V-Notch (well at the time was more of U-Notch having been worn out then) obstacle at Hollister; the 4Runner
HATED having one wheel in the air and the opposite corner not getting good traction, it kept trying to nanny/mimic a locking diff but wouldn't let me get the acceleration I needed to "bump" the 4Runner over to let the free spinning wheel catch the next edge of the notch obstacle; it was so violently rocking/jerking the truck that we all though it'd snap a CV axle. I eventually had to pull the ABS Relay and force a full failure of the ABS system to get it to let me rock the 4Runner the way I needed (I think we may have even thrown a strap on the front to provide forward tension, it's been years.)
The 5th gen A-TRAC is more mature as is the Skid Control ECU programming, but I am sure if you search the forums you'll find that it still likes to try and take control from the driver despite the "OFF" warning lights being on in the combination meter. Point being that Toyota and other manufacturers don't build these vehicles for skilled drivers, they build them to the most common denominator, clueless people who barely understand how to operate the vehicle and they don't trust them even if they push the "safety nannies off" buttons.
-In regards to Inv4drZm's points, 4WD does not affect the braking performance of the vehicle directly. Having 4WD does not improve braking performance or make the vehicle suddenly stop any different than a similar 2WD model (though I will point out that some vehicles get upgraded brakes when you select the 4WD option, so performance might be improved because of that).
That being said, 4WD does have the
potential to improve traction and to allow the vehicle to better control itself in low traction situations. It does this because when the vehicle sees a wheel slipping it'll start engaging the ABS/VSC/TRAC system to control it, I have noticed that most safety systems like VSC/TRAC on Toyotas and other brands just don't seem to be able to handle icy conditions well (even when "Snow" mode is selected). I think it's because they prioritize managing wheel slip versus, since managing a controlled slide is an advanced driving technique and reliant on the driver's skill. Many times if one or more tires starts to slip on ice, the VSC/TRAC system kicks in so aggressively it will break the other tires loose and the vehicle just starts sliding while the car constantly keeps trying to prevent them from locking up which just extends the slide and you have no real control of the vehicle (see it every winter with my own 4Runner and other vehicles). I often joke that VSC/TRAC is trying to kill me in the winter...
With AWD/4WD you have a somewhat lower likely hood that one or more tires will start spinning/slipping at significantly different speeds (still possible if you're really trying, but less likely in general) because the AWD/4WD system is either managing torque output and/or the axles are locked together through the center differential. This in theory could allow you to have better control in those situations without the VSC/TRAC trying to take control away from you, in practice it seems to be 50/50 in my experience.
4WD is a tool that can compliment decent skills and driver aptitude, it is not a panacea nor an automatic improvement in braking or driving prowess by simply having it on the vehicle as an option. You can offset a 2WD vehicle's issues with better winter tires or better driving skill vs. someone with a 4WD vehicle with improper tires and poor driving skill. This is often why you see so many AWD/4WD vehicles spun-out in the winter, too many people get too confident and/or think that because they have those systems they don't need to adjust their driving for the conditions.
~
Long story short, 2WD vs. 4WD comes down to preference, cost, application, and opinion. Personally?
They're called Rav4 & 4Runner, not Rav2 and 2Runner; I never saw the point of selling a 2WD option for these vehicles when they are being advertised for adventure/off-roading/trails, even in a lot of the marketing crap you might see a "this is a AWD/4WD model pictured". If you're looking for a capable Truck/SUV for on-road and off-road use and you're not happy with a Honda Ranchero (Ridgeline) or a Highlander, and are looking at a BOF Truck/SUV then in my mind there is no question, you get the 4WD option.