Quote:All-wheel Drive
As the name implies, all-wheel drive (AWD) feeds power to each corner. Depending on the system (designs vary), AWD can provide maximum forward traction during acceleration. It is especially helpful in sloppy road conditions and when driving over moderate off-road terrain. It can help get you going and keep you moving through mud, sand, and other loose surfaces. Most AWD systems deliver power primarily to one set of wheels, front or rear. When slippage is detected at one axle, power is diverted to the other axle, in hopes of finding more traction there.

Not all AWD systems are equal. Subaru’s AWD system always directs at least 20-percent of the engine’s power to the rear, and it can direct a larger amount aft if needed. Many other systems fitted to front-wheel-drive vehicles operate with 100 percent of the power normally going to the front wheels; the rear wheels then only receive power only when the front wheels start slipping.

AWD systems are especially helpful in rapidly changing conditions or when driving on a road with intermittent snow and ice. It is commonly used for car-based SUVs, as well as certain cars and minivans. (See our list of best AWD vehicles.)

Four-wheel drive
Although four-wheel drive (4WD) and AWD are designations that are often used interchangeably in advertising and sales literature, there is a difference. Generally, 4WD is optimized for severe off-road driving situations such as climbing over boulders, fording deep water, and tackling steep hills with loose, low-traction surfaces. Most 4WD systems have high and a low gear range, the latter used to increase low-speed climbing power. Some have differentials (which allow left and right wheels and front and rear axles to turn at different speeds) to be locked for maximum traction.

Modern 4WD systems are either full-time, which means they stay engaged; automatic, where the vehicle automatically switches between two- and four-wheel-drive mode; and part-time, which require the driver to manually shift between two- and four-wheel drive. Vehicles with a part-time system shouldn’t be driven on dry pavement when in 4WD mode, which could risk damage to the vehicle's drivetrain.

Senor_Taylor Wrote:Now comes the question, if it has a center diff that can NOT be locked, is it 4wd? This article seems to imply that it is, and I do not agree with that.

V1GiLaNtE Wrote:

Senor_Taylor Wrote:Now comes the question, if it has a center diff that can NOT be locked, is it 4wd? This article seems to imply that it is, and I do not agree with that.

I don't think so Taylor. That sounds more like how the Subaru All-wheel drive system works. It does indeed have a center differential, but is not a selectable for locking. That I believe, is the workings of a viscous style differential where it detects slippage of the wheels and provides the power where necessary.

D_Eclipse9916 Wrote:next we will say what is a sports car or not. :lol:

Beej Wrote:So if you don't have LSD's, I assume modern traction control systems that can brake individual wheels make up some of the difference?

rherold9 Wrote:Separate sets for seasons. If you have the monies of course. Good snow tires like Blizzaks will make any 2wd feel invincible. Would be impossible to get stuck with 4wd and Blizzaks

Jake Wrote:I really think my F150 would be fantastic for this stuff if it just had better tires. Nate's truck was leagues better because of the BFG's. But, his tires would suck for extended highway drives which is all I do.

Jake Wrote:Not sure Blizzaks would help here either, the more knobby tread of the BFG's were what could dig in to the deep snow and move it. Blizzaks aren't quite so aggressive.

ScottyB Wrote:

Jake Wrote:Not sure Blizzaks would help here either, the more knobby tread of the BFG's were what could dig in to the deep snow and move it. Blizzaks aren't quite so aggressive.

its not the aggressiveness of the knobs, its the siping within the tread blocks (all the little cut-lines in the tread) along with compound and tread depth to an extent. mud terrains with big, solid knobs are remarkably poor in the snow for that reason. most snow tires look completely pedestrian going strictly by tread look but the grip is eye opening....there's a lot of weird tech behind compound and tread design for that stuff that seems like it wouldn't work.