How / Why does 4x4 work?!

[RobW]

Usually I can get my head round why it is easier to move in a 4x4 in slippy conditions?

2wd - lots of wheel spin and mostly a struggle.

Why don't the 4 wheels spin?

Sorry for a stupid question but it perplexes me.

[sshooie]

they do spin it just takes longer before they do as the traction/slip is split over 4 wheels.

[m8internet]

Think of it like this
Would you rather be on ice, as yourself, or a spider...

[sshooie]

from Google

# Full-time 4WD (or permanent 4WD) means the vehicle is constantly providing power to all four wheels, usually with power being shifted between the front and rear axles as needed. This provides maximum traction in both dry and slippery driving conditions and requires no action from the driver to activate it.

IMPORTANT: Full-time 4WD doesn't provide as much mobility off-road as part-time 4WD does, because the system is designed such that it allows a set of wheels (front or rear) to spin if they don't have traction.

# Part-time 4WD refers to a vehicle with selectable 4x4 or 4x2, requiring the driver to manually shift between 2WD and 4WD using either a lever or a switch. With part-time 4WD, you can "shift on the fly" (switch between 2WD and 4WD while driving). Part-time 4WD gives you better traction on slippery surfaces because the front and rear sets of wheels are locked together. Thus, this is the optimum choice for most off-road conditions.

IMPORTANT: Vehicles with part-time 4WD systems should not be driven on dry, smooth road surfaces when in 4WD mode, or you will soon be spending a lot of money on repairs.

# Automatic 4WD is a full-time system that lets the vehicle operate in 2WD (either front or rear) until the system judges that 4WD or AWD is needed. It then automatically routes power to all four wheels, varying the ratio between front and rear axles as necessary. Usually a slipping wheel activates the system, however, some of the more sophisticated systems use software that switches the system to 4WD or AWD during specific driving conditions -- BEFORE a wheel begins to slip.

[Das]

A 4 wheel drive car can and will spin all 4 wheels, saw a A4 3.0 Quattro doing just this today. The advantage with 4 wheel drive is that you have 100% more traction than with 2 wheel drive, its pushing and pulling at the same time. Bare in mind that 4 wheel drive does not mean it will not struggle, a lot of it can come down to the tyres.

[sshooie]

Also to add often the split is not 50/50, it's often 60/40 to the rear.

[SignumPhil]

The problem with any conventional system with diffs is that the wheel that can spin fastest will. So, even 4X4's get stuck. Unless you have diff locks, when you only need one wheel to grip to get you moving. Until you come to a corner, when things get tricky............

Phil

[Big Sig]

Bare in mind that 4 wheel drive does not mean it will not struggle, a lot of it can come down to the tyres.

Along with the skill of the idiot behind the wheel Some people seem to be under the impression the 4x4/awd's cannot get stuck. plus they don't know what or how to use diff locks.

A FWD/RWD on winter tyres is as good or better that a 4x4 with summer tyres imo.

[Marcosuk]

I miss my legacy awd in this weather.. Standard 16inch alloys with good tyres = very very few probs..

[Big Sig]

I miss my legacy awd in this weather.. Standard 16inch alloys with good tyres = very very few probs..

I've recently moved over to a legacy, just no snow to try it on!