AWD vs. 4wd

[Mr. Bauer]

Hey guys, I just bought a 03 4.6L V8 AWD EdB. I wanted a 4wd but ended up with AWD. Can you guys tell me the advantages and disadvantages to having a AWD as aposed to 4wd? Is the power and offroad capabilities of the AWD the same? Does the AWD work on 2wd and only kick in as needed in AWD or is it in 4wd all the time. Sorry guys if is should know this but I thank you for you time in responding, it is greatly appreciated.

 

[410Fortune]

I am not familiar with teh 03 models 100%.

Does your truck have a 4x4 switch on the dash? it has AUTO, 4 hi and 4 low correct?
If it does then you are golden
if it does not have anything then you are full time AWD and thats great for the street but does not comare to real 4x4 mostly because the lack of low range.

 

[chrisis]

AWD you don’t have the ability to lock the front and rear drive shafts.

4wd gives you a 50/50 split of power to the front and rear axles you also don’t get a transfer case with a Low range gear set.


awd usually gets worse mileage tha na 4x4 because you have 4wd all time

you can/do use AWD all the time including dry pavement. It's there in snow, rain, sunny days etc. 4x4 is only for times when the tires can slip when turning because there is no slippage or differential between front and rear axles. So in rain, and dry days it's 2x4 only.

AWD is by far the best for snow driving and general daily driving.
if you like to do any serious off roading you'll want to look at a 4x4 case

 

[Mr. Bauer]

To answer410fortune question, I do not have 4x4 hi or low or auto on the dash.
Chrisis, let me see if i got this right. My awd. is in 4x4 all the time. Never 2x4. It's not the same as auto 4x4 where it switches as needed.

 

['97 V8]

nope. Its full time. THe split is 35/65 front rear respectively.

 

[chrisis]

AWD is 4x4 high all times. never disengage to 2wd.

4x4 auto: when the pcm detect different speeds between front and rear wheels it locks throw the transfer case to 4x4 high.

the only bad for having AWD is that is taking away your gas mileage and you don`t have 4x4 low for offroading.

hope i help.

 

[410Fortune]

it also uses a clutch as the power take off correct? not a direct link like a chain transfer case.....its a viscous clutch

4x4 hi is 50% front 50% rear, big difference

 

[Mbrooks420]

There is very minimal torque delivered to the front wheels as long as they are turning the same. When they aren't the fluid inside the viscous coupling heats and drives the front more. An AWD Explorer won't have much worse gas than a 4x4 model due to the cv axles always turning. As long as you aren't doing anything hardcore you should be fine. I've driven my AWD in very deep, heavy snow and the AWD was more than capable.

 

[Mr. Bauer]

This is all good information and I thank you all for contributing. I was feeling a bit low for not getting the 4wd. But I have one last question. Would i be able to convert my all wheel drive to 4wd simply changing bolt on parts such as the transfer case and buttons on the dash, or is it much more complicated and expensive to do this that I should not bother.
I'm not a rock crawler and live in sunny Southern California, not much snow here. I do plan to take it to tahoe, Big Bear and Mammoth on unpaved trails, maybe some mud and drive during snow fall without having to get off and put chains on. Is it fine as it is to perform these tasks.

 

[410Fortune]

You will not need chains in the snow with AWD at all, you will be fine.

A 4x4 conversion is not always a simple bolt in deal, as you can see if you search on this site.
Can it be done? yes.
IN a 2003 model (Gen III) it would be very expensive.
Your AWD system will perform great for the uses you list

 

[Mbrooks420]

I wouldn't waste the money on a stock 4wd system swap. the stock 4wd sytem uses an anemic, short lived elctromagnetic clutch that is prone to failure. For occasional off road, AWD should be fine. I had a automatic 4wd Explorer and like the AWD more. True 4wd would do better in real slow speed manuevers, but the 4.6 should have plenty of torque.

 

[Mr. Bauer]

Well, thanks guys, I think I have a better understanding and feel much better about the 03 awd I just got. You guys are great.

 

[red82gt]

I didn't realize that they made an AWD and a 4x4? I guess mine's a 4x4 since it has 4WD auto, 4 high, and 4 low.

 

[gijoecam]

The V-8 4x4s have always been AWD from the factory.

Retrofitting an AWD to have a selectable transfer case is not an easy swap on a 3rd gen. Because the vehicle was never equipped with it, there are no plug-and-play parts from existing Explorers. To use parts from an F-150 or Expedition would work, but again, it's noa a simple plug-and play even though it will physically bolt right up.

I'm not going to re-hash the AWD/4WD differences again. AWD is All Wheel Drive. Automatic 4 wheel drive is just that. The Control Trac A4WD systems also provide you with a selectable 4 high and low range for off-roading, but were/are only available with the V-6. AWD was never an option with the V-6.

-Joe

 

[Mbrooks420]

The 3rd gens came with AWD or control trac. They did this when they switched to one transmission for both motors.

 

[skawtland]

Recently bought an 04 XLS-Sport 4x4. This topic is interesting to me because I thought that the AWD models were RWD until wheel-slippage was detected, where it would then transfer torque to the front wheels as well, therefore "usually" being 2wd for most uses, and thus being more MPG-economical. The AWD models are also rated, I believe, 1 or 2mpg above the 4x4 models.

Mine is a 4x4, and is in 4x4 all the time without being able to go to 2wd. Its default is AUTO 4x4 which as I understand it works similar to the AWD system in detecting wheel slippage, where it directs more torque to the wheels with the most traction. Also it has 4x4 Hi and 4x4 Lo which can be engaged and removes the slippage detection and just puts 25% torque to each wheel.

I'm probably wrong though, but that is what I thought in regards to the AWD versus 4x4 models... AWD models are 2wd (rwd) until poor conditions are detected, 4x4 are full-time 4wd.

I'm new to the Explorer and 4x4's completely, so let me know just how far off I am!

All the best,

Scott

 

[gijoecam]

All wheel drive is not the same thing as automatic 4 wheel drive.

The V-8s all come with AWD. The V-6s all come with the automatic 4 wheel drive and a selectable low range. Their function is completely different.

From the 98 service manual:

The all-wheel drive (AWD) transfer case (7A195) is a two-piece aluminum, chain driven, viscous clutch type unit. This produces a system in which all-wheel drive is always activated. The all-wheel drive transfer case is automatic and has no external controls.

The viscous clutch is a non-repairable, torque distribution device. The internal construction of the viscous clutch consists of alternating plates that are connected to the front and rear outputs of the transfer case. The viscous clutch is filled with a high viscosity fluid which flows through slots in the plates. The resistance to shear causes the plates to transmit torque at the needed ratio. The ratio that torque is transmitted at is approximately 35% front and 65% rear.

A front differential compensates for the difference between the inner and outer wheels. However, when one driveline component travels farther than another, there will be driveline or torsional windup that must be released.

Operation

Torque is transmitted through the input shaft to the planet carrier assembly. Torque flow continues through the gear ring to the rear output shaft. Torque also flows from the planet carrier assembly to the sun gear shaft, which is splined to the drive sprocket. The drive gear is connected to the driven sprocket by the drive chain. Torque continues through the driven sprocket to the front output shaft flange. The viscous clutch provides the connection between the gear ring and the sun gear shaft.

Now, for the automatic 4wd: (accent added)

The Borg-Warner 44-05 transfer case is used in the Explorer (4WD) vehicle. The transfer case transfers power from the transmission to the rear axle, and also to the front axle when electronically activated.


Mechanical Operation

In the 4X2 mode, torque from the transmission is transferred to the input shaft (7017) which, in turn, drives the rear output shaft that drives the rear axle assembly (4006). The 2WD through 4WD auto shift is accomplished through an electromechanical ball ramp clutch assembly.

The electromechanical ball ramp clutch assembly drives the drive sprocket after the GEM activates the clutch coil. The drive sprocket turns the chain which rotates the front output shaft and front driveshaft (4602).

The high-low shift is accomplished when the reduction shift fork moves the reduction collar to lock the planetary gear set to the output shaft. Torque from the input shaft is then transmitted through the sun gear, which then turns the front planetary gear set front planet (7A398). The front planetary gear set front planet which is now engaged provides transfer case speed reduction.


Transfer Case Functions

There are three modes on the transfer case, Auto, 4WD Low, and 4WD High. Neutral is only available as a dealer installed option.


C-Trac Function

The C-Trac transfer case transmits torque to the front wheels through an electromechanical clutch assembly. In the Auto mode, while at rest and under cruising conditions, the Generic Electronic Module (GEM) activates the transfer case clutch at a minimum level. This allows for the slight difference between the front and rear driveshafts which occurs normally when negotiating a corner on dry pavement. Under any of the following conditions, the GEM will increase the torque sent through the clutch to the front wheels in order to prevent or control slip.

l Slip is detected (by monitoring the Hall Effect Sensors in the transfer case)

l Heavy acceleration (by using the throttle position signal from the EEC)

l Very light or zero throttle at speeds above 64 km/h (40 mph) (using the throttle position signal from the EEC)

Range Function

In the 4WD Low Range, the transfer case electromechanical clutch locks the front and rear driveshafts for maximum 4WD traction. The transfer case motor also rotates the shift cam to move the reduction fork to the 4WD low range position. This low range shift is accomplished through a planetary gear set which changes the torque to the driveshaft from 1:1 to 2.48:1 ratio.

In the 4WD High Range, the GEM locks the front and the rear driveshafts for maximum 4WD traction. This position is not meant for use on dry or merely wet pavement. It is intended for off-road or severe winter weather use only.

Completely different functions.

Make sense?

-Joe

 

[skawtland]

I didn't realize that they made an AWD and a 4x4? I guess mine's a 4x4 since it has 4WD auto, 4 high, and 4 low.

Yeah they sure did. Not sure if the 06+ models offer the same, but certainly in my Explorers year (2004) and probably from 2002+ they offered 2wd, awd or 4x4 versions. The 4x4 and AWD models were priced exactly the same though... just to make things more difficult!

 

[Mbrooks420]

Again, the third gens came in v8 4x4, or AWD. Unfortunately 4wd just sends 50% of the power to both axles, and not 25% to each wheel. Both rear tires might have so power if you have a limited slip, but the front end will end up one wheel drie.

 

[gijoecam]

I should have qualified my earlier statement... all second-gen V-8s came with AWD, and all second-gen V-6s got the A4wd. I've never looked closely at the specs on the 3rd gens to see what was available.

So, you mean to tell me that you can get a V-8 with a selectable transfer case? Or do you still get no low range, just automatic 4wd with the v-8s?

If my memory serves, (and from flipping through the service manuals) for the 3rd gens, didn't they do away with the AWD and go to either a 1-speed or 2-speed torque on demand system for the '05 model year?

Just skimming the shop manuals, for '03, they list info for the AWD systems, the one-speed Torque-On-Demand system, and the 2-speed selectable TOD system. Doesn't that mean all three were likely available? I've never seen or heard of a V-8 equipped with a 2-speed transfer case, so that would limit it to the AWD or the 1-speed TOD case for '03, right? I suspect that the V-8s in '03 would have AWD, where the V-6s would have the single-speed cases (thinking Mountaineer, maybe?)

Wish I had access to the build books to see. I used to be able to find them online but haven't seen them in a couple of years....

-Joe