Difference between 4x4 and 4WD

[funnyman82]

I was talking to someone the other day and he was saying my truck is not really a 4x4 he said it was 4 wheel drive. What is the difference? And what do i really have? I have a QX4. It has a switch which turns from rear wheel drive to auto to 4 wheel lock and then there is one called 4LO for slow torque driving....

Thanks.

[Dr.Dan]

4x4 and 4WD are one in the same.

There are many different types of systems out there, but they all come down to one thing... they apply driving force to all 4 wheels ;)

A truck that was just driven by the rear wheels would be a 4x2 or 2WD.

[MSE OP]

there are four major types of drive trains I think
fwd front
rwd rear
awd all
4wd four

[don4life]

Whats the difference between 4wd and awd? AWD is for sedans/wagons like Audi's and Subaru's?

[MSE OP]

Whats the difference between 4wd and awd? AWD is for sedans/wagons like Audi's and Subaru's?

I'm no expert but I think the difference between the two (Awd and 4wd) is Awd is fixed and 4wd you can engage all the wheels or just use two for drive power.

[Dr.Dan]

Whats the difference between 4wd and awd? AWD is for sedans/wagons like Audi's and Subaru's?
buickgnx pretty much summed it up.
AWD is a full time permanant 4 wheel driving system, whereas a 4WD you can engage and disengage 2 of the 4 wheels by either an electronic switch or manual lever.

[Mr. Apollo]

AWD also implies some sort of power shift ability. In an AWD setup there is the ability to send power from the wheels that slip to the wheels that grip via mechanical or electronic clutches. 4WD or Full-time 4WD is just fixed at 25% power to each wheel.

Your QX4 is 4x4 or 4WD what it does have is "on demand 4WD" basically it can be set up so it's RWD until the rear wheels start to slip then it sends power to the front. There are several vehicles like this (in some cases like the Volvos they are FWD until the wheels slip and then power is sent to the rear). Some people consider these vehicles AWD and others do not. AWD usually implies that some amount of power is going to all four wheels all the time.

[Lesster]

AWD also implies some sort of power shift ability. In an AWD setup there is the ability to send power from the wheels that slip to the wheels that grip via mechanical or electronic clutches. 4WD or Full-time 4WD is just fixed at 25% power to each wheel.

Your QX4 is 4x4 or 4WD what it does have is "on demand 4WD" basically it can be set up so it's RWD until the rear wheels start to slip then it sends power to the front. There are several vehicles like this (in some cases like the Volvos they are FWD until the wheels slip and then power is sent to the rear). Some people consider these vehicles AWD and others do not. AWD usually implies that some amount of power is going to all four wheels all the time.

Good info Mr Apollo

Both of our Ford Explorers, the one now driven by our son & his wife, a '97 and the '04 we bought this year have buttons (4WD Hi & 4WD Lo) on the dash to switch to 4WD. However the '97 also has something called "Control trac" that switches the drivetrain to 4WD automatically if any wheels slip or loss of traction is "sensed" by the system. The '04 does this as well, don't recall if it's still called the same thing. Under normal conditions it is a RWD.

This also means that when such vehicles have to have the Drive Clean Emission Test they can't be put on a dyno; they just have a curb idle test - which is much less stringent. They can't be put onto a dyno because there is no way to prevent the front wheels from joining the rear wheels as "drive wheels" and so the vehicle has to be tested in the same manner as an AWD.

[Mr. Apollo]

^^^ I know Subarus have a fuse box labelled "FWD" under that hood that can have a fuse placed into it to disable the AWD system and keep the vehicle in FWD only for emissions testing. I don't know of any other vehicles with this feature though.

[funnyman82]

Thanks for the info everyone...helps a lot...now to have a talk with my co-worker!

[don4life]

Ya very useful info about awd/4wd. Thanks.

[Mr. Apollo]

If you ever see as vehicle with "full time" 4WD basically that means you can drive around with 4WD on all the time. Most trraditional 4WD systems are for use in slippery conditions only as the centre differential locks which causes havoc when turning corners since the wheels cannot turn at different speeds. This can ruin your drivetrain very quickly. Full-time 4WD (as opposed to Part Time 4WD) allows the centre differential to remain open allowing the wheels to turn at different speeds around corners.

Full-time and part-time 4WD are different from 4WD LO. 4WD LO uses a different gear ratio which keeps the engine in it's peak power band. It's only for slow speeds (20 - 30 km/h and below) but your engine will be revving at about 3,000 - 4,000 RPM. It is only for driving off road in very poor conditions.