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I am a new owner with an 06, 4WD, Tech, ... Anyway, the explanation in the manual regarding four wheel drive is less than clear. I have owned many all wheel drive vehicles, and several true four wheel drive as well. If I go to 4H, does this in fact lock the center differential giving me true four wheel drive?
 

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Carson said:
I am a new owner with an 06, 4WD, Tech, ... Anyway, the explanation in the manual regarding four wheel drive is less than clear. I have owned many all wheel drive vehicles, and several true four wheel drive as well. If I go to 4H, does this in fact lock the center differential giving me true four wheel drive?
4H locks the differential front to rear. Auto allows use on dry pavement.

Keith
 

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Welcome aboard. :)

Just to clarify. 4H locks center differential. Which means the front shaft and the rear shaft are turning at the same rate. The front and rear differentials remain open. There is where VDC does its job to control slippage. 4L does the same thing except with lower gearing.

my $0.02.

Cheers !!!
 

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4wd

There is no center differential, there is a transfer case. The transfer case is no different than any other part time system when in 4h and 4l. The difference is the auto feature that allows you to run 4 wheel drive on any surface, which is similar to a “center differential” found in Subaru, Audi and others. It too uses clutches in the t-case to achieve proper wheel slip. When the t-case is in 4h or 4l the t-case is fully locked providing equal force to front and rear diffs. VDC is controlled by the engine, transmission, and brakes and has nothing to do with the t-case or differentials.
 

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SE Off Road1 said:
There is no center differential, there is a transfer case. The transfer case is no different than any other part time system when in 4h and 4l. The difference is the auto feature that allows you to run 4 wheel drive on any surface, which is similar to a “center differential” found in Subaru, Audi and others. It too uses clutches in the t-case to achieve proper wheel slip. When the t-case is in 4h or 4l the t-case is fully locked providing equal force to front and rear diffs. VDC is controlled by the engine, transmission, and brakes and has nothing to do with the t-case or differentials.
Some 4wd's DO have a center differential to control the amount of power to the front and rear (i.e. Range Rover), the Armada does not have this. Some 4wd's allow you to lock the front/rear diffrentials...Armada doesn't have this, and some 4wd's have true limited slip differentials...the Armada doesn't have that either!

It has open differentials front and rear and slippage is controlled by the computer via the brakes. When you put it into 4H or 4L the power is evenly distributed to the front and back and this cannot be altered.
 

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4wd clarification

THanks for the clarification. For us non-techies, what does that mean? Can we drive around all day in AUTO mode? WHat happens in this mode? If it is wet, will this mode help you with traction or is 4H better on paved roads. I guess I am getting confused with my Touareg which had full time AWD so power could instantaneously be transfered to whichever wheel had the best traction. The distribution was 50/50 front vs rear whereas it's cousin the Porsche Cayenne had a rear biased 40/60 distribution thus enhancing it's road feel much like that of a rear drive sedan. In the event of sliipery road conditions, power would be transferred instantaneously to the front if needed.
IS the armada 4x4 an inferior system? Please clarify anybody!
 

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The Armada's front and rear drive shafts are "locked" at the same speed in 4hi or 4lo at the transfer case which is why you should not drive on high traction surfaces in either mode, and I believe there is a center differential at the transfer case that is "open" in 4wd auto to allow it's use on high traction surfaces. 4hi or 4 lo should be only used in low traction situations; loose gravel, snow, ice etc.... Wet roads are not "slippery" enough for anything other than 4wd auto, 4hi and 4lo will bind the drive line. The answer is yes you can use auto mode anytime for as long as you want, there will however most likely be a slight mileage penalty and there will also be wear on the front drive component vs. none in 2wd.

The problem is the front and rear axles are mechanically tied together (4hi &4lo) and the front and rear wheels travel different distances when making turns, there needs to be some tire slippage to prevent drive line binding.

As far as the Armada 4wd system; it uses the ABS wheel sensors to detect wheel speeds and applies the brake to the wheel with too much speed which effectively transfers power to the wheel on the other end of the axle. As far a VW system being superior; maybe on road but I don't think they have lo range, do they?
 

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No. the Armada does not have an inferior 4x4 system. Let me take a stab at trying to explain what we have and what we do not have and how it differs from other systems.

The Toureg and other european (and some Japanese) four wheel drive vehicles rely upon a full time system which is a good compromise for vehicles which are mostly used on the highway but which encounter slippery conditions like snow and ice. It is a good system.

That system usually has a center differential, typically a Torsen type system that lets that center diff distribute power as the computer tells it and sometimes, in centain models, allows it to be locked for true off-road work. This system is smooth, but it consumes more fuel and tends to wear out parts more quickly than other systems. It is expensive.

On the other hand, those of us who are seriously into off roading prefer to have separate differentials front and rear with a transfer case in the middle that allows all the power to go to the rear axle under normal conditions, or to select 4 high or four low, to send power to the front axle.

Differentials that are open only send power to the right rear and left front respectively unless there is some type of traction control system. Limited slip systems, usually with clutches, but sometimes with gears, can transfer some of the torque to the other axle. Locking differentials utilize a ratcheting system that locks both left and right axles on a differential to each other, but still allows one side to ratchet when going around corners.

These systems can be full-time or part time and can operate several ways. A part-time system actually interrupts the power to the front differential at the transfer case. Such a system, when in 2wd, does not turn the front drive shaft, and thus does not turn the front differential or axles. This is the simplest and most fuel efficient. When in 4 high or 4 low, the front drive shaft turns, which activates the front differential and axles.

We have a full time system, but with front hubs which lock and unlock electronically. If you select 4 high or 4 low, the front hubs lock, and power is applied to the front. Until then, however, the front hubs free-spin, even though the front drive shaft, differential and axles turn all the time.

When in "auto" mode, you are in 2wd high range. But since the front drive train is always spinning except for the front hubs, the computer can be programmed to sense a slipping tire at the rear of the vehicle. It uses the ABLS system, which has sensors that detect whether one wheel is turning faster or slower than the others. Upon detecting slip at the rear, the computer will lock the front hubs, activating the front system.

ABLS (automatic brake limited slip) also adds the feature of working like a limited slip differential for each axle. The computer detects slip and transfers power from the slipping wheel by applying braking to that wheel. This transfers torque to the other wheel on the same axle.

So, most people familiar with this system would recommend keeping the selector in "auto" all the time unless you are off road. If in 2wd, you cannot ever get power to the front wheels, because those hubs are unlocked. If in "auto" you get power to the front only when you need it.

In 4 high or 4 low, you get power to the front even when you do not need it. There is no clutch or viscous coupler in this system and if 4 high or 4 low is engaged and you are on hard pavement, you can get drive train bind and things can break if a wheel on one axle is turning faster than a wheel on another axle, such as when going around a corner.

Our system represents a very smart electronic solution to the problem of how to get traction to all four wheels, only when needed. This system does work very well, but does make some noises when the hubs lock in and unlock and when brakes are selectively applied to one side and not the other.

A dedicated off-road system (my CJ-5 Jeep is an example) would have a manual, selective transfer case that with modification can even allow you to have front wheel drive only, rear drive only or both, and typically would have manual locking hubs on the front axles which you lock or unlock by a twist of a know at the center of each front wheel. You manually control everything.

That system would usually have a real full-time locking differential in the rear, and either another locker or a limited slip in the front. That is the best system for playing in the dirt, but can have some adverse effect on handling on pavement.

I hope this was more help than confusion!
 

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Armada said:
We have a full time system, but with front hubs which lock and unlock electronically. If you select 4 high or 4 low, the front hubs lock, and power is applied to the front. Until then, however, the front hubs free-spin, even though the front drive shaft, differential and axles turn all the time.
We do not have auto hubs on our trucks. The hubs are full time hubs and are locked to the front splines on the axles. The front driveline spins constantly with forward motion. The front differential is locked into 4 Wheel drive by the transfer case only. Aside front this one point your summary on our system was very accurate.
 

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Discussion Starter · #11 ·
Shift Lurker,

I too, had a Touareg and liked it a lot except for the service issues with the local dealer. (I also have owned an X5 and a Range Rover.) I now believe that the Armada may have more flexibility with its 4WD system although I do not fully comprehend all of these posts. However, I do think that I now know when to activate each of the modes. Thanks to all who have answered my question.
 

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If ABLS(i thought it stood for anti-lock brake limited slip) is supposed to work like a limited slip diff and rediirect power to the other wheel and brake the slipping wheel. Why is it that that when we do a burn out of get some slip in the rear end only one wheel spins?

Son of SQS
 

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Never done a burn out (tire$) but have pulled a heavy trailer (8k+)up a very steep loose graveled dirt hill. The witnesses said they saw the wheels spin and then-stop-start-stop for half way up the 300ft hill until I got some momentum going. I was not at full throttle, but well over half way and I was in 4wd lo range. ABLS seemed like it was kicking in because the previous year a 3/4t Dodge CTD 4wd could not get the same trailer up the same hill (dryer conditions too) without a 2wd truck helping it with a tow strap. We had that same Dodge on hand to help the Armada if needed, needless to say the Dodge owner was impressed.
 

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Now *that* is what I am talking about! AWESOME!!! Make that Armada earn its fuel/dinner baby! LOL

ST :3d_004:

Cillyone said:
Never done a burn out (tire$) but have pulled a heavy trailer (8k+)up a very steep loose graveled dirt hill. The witnesses said they saw the wheels spin and then-stop-start-stop for half way up the 300ft hill until I got some momentum going. I was not at full throttle, but well over half way and I was in 4wd lo range. ABLS seemed like it was kicking in because the previous year a 3/4t Dodge CTD 4wd could not get the same trailer up the same hill (dryer conditions too) without a 2wd truck helping it with a tow strap. We had that same Dodge on hand to help the Armada if needed, needless to say the Dodge owner was impressed.
 

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Cillyone said:
Never done a burn out (tire$) but have pulled a heavy trailer (8k+)up a very steep loose graveled dirt hill. The witnesses said they saw the wheels spin and then-stop-start-stop for half way up the 300ft hill until I got some momentum going. I was not at full throttle, but well over half way and I was in 4wd lo range. ABLS seemed like it was kicking in because the previous year a 3/4t Dodge CTD 4wd could not get the same trailer up the same hill (dryer conditions too) without a 2wd truck helping it with a tow strap. We had that same Dodge on hand to help the Armada if needed, needless to say the Dodge owner was impressed.
That would have been a sweet video!!
 

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understood Armada's post but SE OFF road lost me

Hey y'all:

Thanks for everyone's expertise and comments. Y'all are a great resource. Armada's explanantion made the most sense but SE Offroad's clarification went above my head. SE can you explain in layman's term. As an anesthesiologist, this mechanical stuff is way over my head. Now if you want to talk pharmacology we can:)

Gasdoc
 

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Great explanation. One question though, if this is true, and in AUTO the front drive shaft, differentials, etc. are always turning then on paved, dry roads if I am running in AUTO:

1. The computer should not be sending any power to the front end
2. I should not take a MPG hit.

Is this right? Do 2WD and AUTO get the same MPG when on dry, well surfaced streets?
 

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tpartridge said:
Great explanation. One question though, if this is true, and in AUTO the front drive shaft, differentials, etc. are always turning then on paved, dry roads if I am running in AUTO:

1. The computer should not be sending any power to the front end
2. I should not take a MPG hit.

Is this right? Do 2WD and AUTO get the same MPG when on dry, well surfaced streets?
No, when you come to a stop (for a light lets say) the car puts it in auto and as you start moving it'll put it in RWD and it'll put it in 4wd when the computer senses slip.
 

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I don't know about you guys, but I can feel the difference between 2WD and Auto mode, there is more roll resistance and the sense of not quite, but almost binding feel.
 

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Auto/4WD

tpartridge said:
Great explanation. One question though, if this is true, and in AUTO the front drive shaft, differentials, etc. are always turning then on paved, dry roads if I am running in AUTO:

1. The computer should not be sending any power to the front end
2. I should not take a MPG hit.

Is this right? Do 2WD and AUTO get the same MPG when on dry, well surfaced streets?
I'm not sure, the question on MPG is up for debate. I would say the difference would be negligible. I would not run auto on dry pavement either way but you can if you would like too with no harm to the driveline. The transfer case is engaged but uses clutches (similar to an LSD) while in Auto. Once in 4H or 4L the clutch is locked like any part-time system transfer case. Since the transfer case is still engaged in Auto I’m inclined to say the MPG would drop in Auto as well.

If you guys noticed there is a filter on our transfer case. This filter is used to catch material from the clutch pack which auto mode creates. My on-line shop manual covers changing this, it is very easy but should be torqued to prevent deforming the seal. I would be happy to share the detail on the transfer case to anyone interested. I use Auto in heavy rain and would also use it on partial snow covered roads. In mud or washed out fires roads or snow covered roads I would use 4H. I limit its use to when really needed to prevent unnecessary wear on the transfer case.

Armoody, you are right. You can “feel” the difference between Auto and 4H. This is because in Auto the transfer case is engaged but not locked. It only locks when wheel slip is detected.
 
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