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Auto 4WD Full Time Use? Good or Bad?

miket-av

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Hello,

I actually just picked up a new '04 Z71 WBH, Dark Blue about 10 days ago. I have done a few forum searchs on the topic and haven't really seen the answer I am looking for. I live in Vermont and it's pretty much a daily occurence between Dec and April something frozen is coming out of the sky.

I do about 65 miles of highway driving each day. Pretty much every morning the road is wet with something. At -10 who knows what it's wet with but it's damp with something nonetheless.

Here's the question I have had the AV in Auto4 for about 8 of the last 10 days because most of the time the roads is wet, I live on a dirt road that is now hard snow pack and the side roads are usually in some state of snow covered or wet.

Is the Auto 4WD made for that much use? Friday night driving home we had a thin layer of snow - howling winds and a deluge of freezing rain all the way home. With the way the AV catches the wind and the freezing rain and light snow cover it made for an interesting drive - which caused me to go to 4HI and keep it between 45-50mph.

I am trying to find out if this kind of use ok or am I asking for trouble with the drivetrain. When roads are dry it's in 2HI. But with the winter we're having those dry days are few and far between.

The good news is the AV hasn't slipped, skidded, spun out once. Which puts it light years beyond the 5 month old - old style Durango it replaced.

If you have the answers to these questions or a good opinion I would to hear about it.

Thank you and I have found this forum to be a incredible resource. ???
 

sparky

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I have quite a bit of experience with this so feel I can comment.
I use the Auto 4 for anything up to the point where the only thing left with snow/ice is my street. My street (just because there are so few cars on it) is the last to clear.... but I'm ok with just creeping up it.

Other than that I leave it in 4 auto. There is a reduction in gas mileage, and there is 'some' wear, but this is far better than 4hi.

I do not use 4hi or auto 4 for warm/wet roads, just snow and ice.

Having the auto 4 on means that if I happen to end up sitting on ice waiting to make a turn I won;t get a surprise when I try and pull away. I've been driving a front wheel drive the last few days, and trust me I miss the 4 wheel option big time.
 

Chief

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This is a GREAT question! Based on what you're describing I would think that AutoTrac would be the right thing to do on that dirt road home. I think that is a no brainer...

Long term at highway speeds. Hmmmmmmmmmmmm. Certainly running 4-Hi for that time and distance day in and day out would not be a good thing long term.

I can speak from my own experience on when I use Auto Trac. I'll use Auto Trac in very heavy rain with standing water on a road if I'm traveling over 35 MPH. I'll use it if there is freezing rain, or if mister temp gauge supports the chance of ice/freezing rain and the road is wet. If there is snow, ice, or a lot of mud on say a dirt road, then I'll use Auto Trac.

However, if the road is wet from normal rain, snow melt etc. - nope I'll stick with 2-Hi. Also if I feel conditions warrant the use of Auto Trac, I won't go over 60 MPH. If I'm that concerned about traction then I probably have little business going at the higher end of highway speeds. If you lose control (even at 60 MPH) it won't matter if six inch spikes come out of your tires - you're along for the ride.

If the conditions warrant long term use of AutoTrac then I would say the best advice is regular inspections of the differential fluids and go to a "severe" service maintenance schedule.

=================

Also for those who might be reading this - if you don't use your 4WD system often it is a good idea to engage Auto Trac or even better 4-Hi on a nice straight stretch of a road for a few miles to lubricate the system every couple of months.
 

ava_2500

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All my roads and snow is thawing so on backroads I got some mean mush. 2Hi DOES NOT work in that, because the backend hardly weighs anything. I tryed auto 4wd, and Its basicly like switching from a front wheel drive to a rear wheel drive putting the av in weird positions. :7: So for the first time I used 4x4HI, and boy was it everything I dreamed (y). I dont think Id be driving the av these days if I only bought the 2wd model.

Leaving it in auto-4wd is the same as someone who has a f*rd with lock in hubs, and leaves the hubs locked in, and manually shifts the truck into 4x4. Only ofcourse ours is done for us...
Which if there is enough pavment, and turning on dry/lightly wet pavment will screw your ring and pinion in the front end...
Personal rule of thumb--- If I cant see/feel parts of the pavment/gravel... its going in auto 4wd. If I'm stuck, or not going anywhere fast in 4x4 it goes. Also depending on the degree of stuckness I will use 4x4lo.
 

Z71offrd

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I love my Auto-4. :love:

Haven't looked in the Av's manual, but in my 2000 Tahoe, GM said that you could theoretically put the truck in Auto4 for the rest of it's life. You will lose 1-2 mpg while using it, as it spins the front axle. The Auto part is that it engages the electronic hubs when it detects wheel slippage.

When the roads are snowy, I tend to just use 4Hi. When it's a mix of wet/dry/snow, Auto4 is perfect. In the summer, I use the Auto4 during rain storms too. It's worth the small hit in mileage for the potential traction/control benefits.

As for highway use, if I am in Auto4 when I get on the highway, I don't bother to put it back into 2Hi for the short <15-20 mile trips I take.

Mike :B:
 

miket-av

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Hey good responses so far but it doesn't seem to answer the question. The manual says for AUTO 4WD the front axle is engaged but power is sent only to the rear wheels unless their is a loss of traction - in which case the front will get power. The only penalty according to Chevrolet is slightly lower fuel economy.

So it's reads like it's on-demand AWD (in theory) when needed. And the highway conditions I wrote about it's more like a glaze - every morning - not quite black ice but not just water.

It's been above 32 twice since December so I don't think it's water. Vermont's like Alaska but actually attached to the mainland.
 

I CHNGE

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miket-av said:
Vermont's like Alaska but actually attached to the mainland.

Uuuuhhhhh.......Alaska is also attached to the mainland...just not to the "lower 48"!!! :rolleyes:
 

04ArrivalBlueZ71

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Greetings from frozen Michigan. Yes, use that Auto mode whenever you feel like it, and don't worry about the wear. That's what we paid for! Paid for it, use it. Break it, get a new one.
Only thing about mine, is when I get above 60 mph in Auto mode it gets real noisey. My '01 Silverado Z71 didn't make noise even up to 75 mph, but this Av does. Nasty noise. I guess that will keep me from driving too fast in marginal conditions then. One thing for sure, with the extra weight on the rear wheels as compared to my extra-cab truck, I can stay in 2 HI longer. This AV is far superior in 2 HI as compared to my '01 pickup in deep snow.
 

fireeater

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I hardly ever use the Auto or 4HI. Like 04AVblue said this truck is heavy enough that it rarely needs it and goes through the snow supurebly!!
 

RichUF

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2Hi DOES NOT work in that, because the backend hardly weighs anything.

I'm just a dumb southerner (Floridian, no less) that knows jack about driving in sloppy winter weather. However, I'm getting a little bugged by the several times I've seen this posted now. People, the Av has a near 50/50 weight distribution. How this can equate to the back end being light is just beyond me. Someone educate this sunny flatlander please before I go crazy.

Thanks.
 

mvfd03av

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I love to push auto-4 at a red light next to almost anything other than a Quattro when the road is wet... >:D

I love it when they hit the paint lines and their tires break loose while I blast off! (y)

I use auto most of the time on pavement unless it's really nasty. off-road is usually 4_hi.
 

RichUF

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mvfd03av said:
I love to push auto-4 at a red light next to almost anything other than a Quattro when the road is wet... >:D

I love it when they hit the paint lines and their tires break loose while I blast off! (y)

I use auto most of the time on pavement unless it's really nasty. off-road is usually 4_hi.

again JMO, but [presumably, based on post] WOT and transfer case engagement don't go well together. Sounds fun, though >:D
 

midlifecrisis

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I concur with most posters here:

Dry, or wet and warm pavement - 2 HI

intermittent ice/snow - AutoTrac

consistent snow/ice - 4 HI

I also agree that if conditions warrant use of AutoTrac, then you shouldn't be driving at excessive speeds anyway.
 

crott

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Just one thing concerning wear - and remember, this is just an opinion.

First, what I beleive is fact: driving in Auto-4 has the half shafts engaged at all times, and when the truck's rear wheels spin, the transfer case automatically engages the front wheels to help out.

Now for the opinion part... I would think that long term use of Auto-4 that has lots of engage/disengage would put you at risk of premature failure of the mechanism in the transfer case that engages the front wheels. Everything else has nice big bearings that turn, and running several thousand miles shouldn't hurt anything except gas mileage (like the manual indicates).

For what it's worth, I'd minimize the quick starts on known slick surfaces where the transfer case must engage the front wheels. It just seems that there has to be quite a bit of stress when the rear wheels start to spin, and the front ones are suddenly engaged...

Just another opinion - butit's free, so at least you got your money's worth!
 

chethammer

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crott said:
Just one thing concerning wear - and remember, this is just an opinion.

First, what I beleive is fact: driving in Auto-4 has the half shafts engaged at all times, and when the truck's rear wheels spin, the transfer case automatically engages the front wheels to help out. 

Now for the opinion part...  I would think that long term use of Auto-4 that has lots of engage/disengage would put you at risk of premature failure of the mechanism in the transfer case that engages the front wheels.  Everything else has nice big bearings that turn, and running several thousand miles shouldn't hurt anything except gas mileage (like the manual indicates).

For what it's worth, I'd minimize the quick starts on known slick surfaces where the transfer case must engage the front wheels.  It just seems that there has to be quite a bit of stress when the rear wheels start to spin, and the front ones are suddenly engaged...

Just another opinion - butit's free, so at least you got your money's worth!

I can tell you from experience that your opinion is correct.  Not only will it mess up the front Differential, but it will also do damage to the rear.  I got lucky that the dealership had problems diagnosing it and only charged me for the price of the front.  Otherwise the price to do both is almost $6000.  So be forewarned that if you drive any truck with the same general capabilities as the Avalanche, whether it is a Ford, Dodge, Chevrolet, Nissan, or Toyota, in AUTO all the time you will pay. 
 

2004Slickside

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chethammer said:
I can tell you from experience that your opinion is correct.  Not only will it mess up the front Differential, but it will also do damage to the rear.  I got lucky that the dealership had problems diagnosing it and only charged me for the price of the front.  Otherwise the price to do both is almost $6000.  So be forewarned that if you drive any truck with the same general capabilities as the Avalanche, whether it is a Ford, Dodge, Chevrolet, Nissan, or Toyota, in AUTO all the time you will pay.
I agree, but why are you quoting a 16 year old post.
 

ygmn

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2004Slickside said:
I agree, but why are you quoting a 16 year old post.
spreading his experience in a thread for future users.
 
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