Difference between 4WD and AWD?

rslifkin wrote:

NOHOME wrote: If you can lock the center differential and both front and rear differentials, you have 4wd. I would imagine that "AWD" means that any of the 4 wheels COULD drive if they have the traction. I have distant memories of locking axle hubs and center differential in 4wd mode that made the truck very reluctant to turn once out of the snow.

By that definition, almost nothing has 4wd from the factory. There's very, very few vehicles out there with locking diffs out of the box.

Hey, if the center diff and both axles are locked, you cant argue that it is NOT 4WD. End of discussion. All other definitions and badging are debatable. That it is a rare thing does not come into play.

Electronic traction control brings a whole new world of fuzziness to the question.

4x4 you can shift into. All wheel drive can be constant or its 2wd until the wheel sensors detect slippage and it goes over to awd.

There are always going to be those that break the mold. But for me:

4wd= transfer case with selectable low range (center diff. locked) and good ground clearance. May or may not be full-time 4WD.

Awd=no low range, unavailable or automatically disengaging center diff lock. May or may not be selectable awd.

In reply to Brett_Murphy:

Bugs me to. Thanks for your answer; now I don't have to type.

Brett_Murphy wrote: Others know what they mean, but it isn't exactly right.

I skip this and just refer to my AWD cars as having "quattro". :)

codrus wrote: I skip this and just refer to my AWD cars as having "quattro". :)

Trademarked, like Kleenex.

Here is a question: Why did Jeep come up with the whole Trail Rated hype?

I argue it is because some of their 4x4s are really "Full Time 4x4" or, as we know it elsewhere, AWD. So, they had to somehow convey that rugged, off-road lifestyle image to people who are never going to do the Rubicon while selling them cars that are pleasant to drive but good in the snow.

Don't get me wrong, Jeep Quadra-Drive and Quadra-Drive II are very capable off-road systems, but they're AWD systems with a low range.

Brett_Murphy wrote: Here is a question: Why did Jeep come up with the whole Trail Rated hype? I argue it is because some of their 4x4s are really "Full Time 4x4" or, as we know it elsewhere, AWD. So, they had to somehow convey that rugged, off-road lifestyle image to people who are never going to do the Rubicon while selling them cars that are pleasant to drive but good in the snow.

IIRC, when they first came out with it, any Jeep that had low range, could ford some specified amount of water and had some specified amount of ground clearance got the badge.

They started using it the same year they made a non-low-range version of the fulltime transfer case optional in the Grand Cherokee for soccer moms (not that it mattered beyond saving 20 lbs and deleting the shifter, the previous fulltime case worked exactly the same if you just never put it in 4lo).

Excluding the 93 - 95 Grand Cherokee quadra-trac, the vast majority of the Jeep fulltime 4wd systems do lock the center diff in 4lo, so they don't really have much disadvantage to a more conventional 4wd system for actual off-road use (just with out a 2wd mode and no manual way to lock the center diff in high range, which aren't very useful for most off-roading where you'd be in low range anyway).

Brett_Murphy wrote:

codrus wrote: I skip this and just refer to my AWD cars as having "quattro". :)

Trademarked, like Kleenex.

Yes, but in my case, accurate nonetheless.

(not pictured, the B5 S4 I sold in 2007)

rslifkin wrote: (just with out a 2wd mode and no manual way to lock the center diff in high range, which aren't very useful for most off-roading where you'd be in low range anyway).

So, they're AWD, with added enhancements to afford them more off-road capability, much like the GC Subaru Forester in Australia.

Brett_Murphy wrote:

rslifkin wrote: (just with out a 2wd mode and no manual way to lock the center diff in high range, which aren't very useful for most off-roading where you'd be in low range anyway).

So, they're AWD, with added enhancements to afford them more off-road capability, much like the GC Subaru Forester in Australia.

Sort of. They still have a user-selectable modes that are mechanically distinct (it was a mechanical shifter for 4lo for quite a few years). It's kinda like being able to select between an AWD mode and a normal 4x4 low range mode. Personally, I'd consider that fulltime 4wd more than AWD. When you delete the low range and it's now a single mode with no user control, then it becomes AWD.

What about the Honda Pilot that is AWD when wheel slip is detected, but you can push a button that locks the difs making it 4 wheel drive to get unstuck?

rslifkin wrote: Personally, I'd consider that fulltime 4wd more than AWD. When you delete the low range and it's now a single mode with no user control, then it becomes AWD.

Fulltime 4wd and AWD modes are pretty indistinct from each other, though. They have to be in order to work well on pavement. I'm not opposed to agreeing that if all four wheels on a two axle vehicle turn at the same speed (such as through lockers) that that is a different mode of propulsion than what most manufacturers label AWD, but all wheels are still driven... so it's all wheel drive. Changing the final drive ratio doesn't change how many wheels are driven, either- on that two axle vehicle, it is still 4x4 or AWD. On something like the Gama Goat, which has 6 wheels, it would be 6x6... or AWD. If the Gamma Goat only drove four wheels, it would be a 4x6, which is not AWD.

It's splitting hairs, sure, I admit that. Since there is no defined industry standard (as far as I'm aware), the meaning of 4x4 vs AWD is really a matter of opinion and general consensus, though.

It gets even more confusing when AWD and 4WD are both offered on the same vehicle, like older Explorers, where the V6 versions offered 4WD, while the V8 offered AWD.

92dxman wrote: 4x4 you can shift into. All wheel drive can be constant or its 2wd until the wheel sensors detect slippage and it goes over to awd.

^This. I also insider 4wd when the front and rear axles are locked together by the transfer case. fulltime 4wd is, like said before, just a fancy way to make AWD sound rugged. I guess the difference for me is if the center diff is locked or not.

The true test in my mind is if it is in 4wd or AWD/full time 4wd or whatever you call it, and you turn to max lock and try to drive in small circles, a true 4wd will bind and be very unhappy where an AWD wont show any signs of discomfort.

there are also some vechicles (fj80 landcruisers) that are AWD but can be shifted into a true 4wd that locks the center diff

even then, there are outliers. nobody would argue that my 2003 Discovery is a 4wd vehicle.. it has two solid axles, a transfer case, and does not even allow shifting into 2wd.. it is 4wd all the time.. yet, when it was built, Land Rover was experimenting with traction control and had decided that the Transfer cases on 2001, 2002, 2003, and 2004s did not need to be locked... as the traction control would work better than locking front and rear axles together.

2005 LR3 had a locking transfer case, so you know how well that worked

In reply to mad_machine:

IIRC-the locking feature was still there on transfer case but there was no handle inside to actuate it. Fairly easily fixed.

from what I have read, that is true on 2001 and 2002.. on the 03 and 04, they even removed the parts the handle's mechanism would bolt to. The lock may still be inside the case, but there is no way to even bolt up the handle to it.

Trust me, I would love to be able to lock the transfer case.. maybe this summer I will crawl under there and see what can be done

One has a center differential, the other doesn't.

Engine sits long-ways with a transfer case it's 4wd. Engine sits sideways it's awd.

Bobzilla wrote: Engine sits long-ways with a transfer case it's 4wd. Engine sits sideways it's awd.

not true in my book. typhoon's, syclone's, pre-98 bravada's, some astro van's, and 5.0 explorer's all had transfer cases but were AWD and advertised as such

edizzle89 wrote:

Bobzilla wrote: Engine sits long-ways with a transfer case it's 4wd. Engine sits sideways it's awd.

not true in my book. typhoon's, syclone's, pre-97 bravada's, some astro van's, and 5.0 explorer's all had transfer cases but were AWD and advertised as such

There's an exception to every rule. Except the sideways engines not 4wd. Longway's and transfer case can be AWD, but sideways can never be 4wd.

the Brits- or at least the guys on Top Gear, the only Brits i care about- called everything with more than 2 drive wheels "4 wheel drive", which my American ears thought was funny to hear when they were thrashing on a Lambo or something on some Italian back roads..

Awd has a center diff, 4wd doesnt. That is ONlY DIFFERENCE between the two systems. You can have open diffs in any location, you can have lsds in any location, you can have Any driveline configuration, although you wont see mid or rear engined, or typically transverse mounted engines without a center diff because no center diff means no driving on high traction surfaces with 4wd engaged.

Some awd systems have a mode where the center diff is locked (typically on suvs/trucks), this allows improved traction in off road situations while still allowing the benefits of the center differential in higher traction situations. Slightly slippery situations where there is light snow coverage on tarmac for instance.

AWD is like pornography. You know it when you see it.