No more AWD?

jrhaines2 · February 23, 2019

From Carfax.

All-Wheel Drive Basics

Let’s get a basic understanding of how all-wheel drive works before we dive into the configurations of this system. For a vehicle to have all-wheel drive, it has to be equipped with a center differential. A center differential is a set of gears that splits power from the transmission to the front and rear axles. Helping out the differential out are wheel sensors, which detect traction loss, wheel speed and other data points.

Now let’s look at how all of these components work together. Let’s say you are stopped on a snowy road and you decide to its time to move. You press down on the accelerator and power begins flowing to the wheels, but one wheel is spinning in the snow without gaining any traction on the road. This is where all-wheel drive comes into play. Sensors detect the loss of traction and begin feeding information to the vehicle’s computer. From there, the computer will adjust the amount of power going to each wheel, sending more to the wheels with better grip to get the vehicle moving.

All-Wheel Drive vs. Four-Wheel Drive

All-wheel drive is often interchanged with four-wheel drive in advertising, which causes many people to think they are the same thing. However, there are some key differences between all- and four-wheel drive systems. One of the big differences is how often these systems are on. All-wheel drive is running all the time, varying the amount of power to each wheel. Traditional four-wheel drive systems in many vehicles are classified as part-time systems, which means the vehicle operates in rear-wheel drive until four-wheel drive is selected by the driver. You’ll find part-time four-wheel drive systems in many trucks and off-road SUVs. However, certain models built by automakers such as Jeep and Land Rover have full-time four-wheel drive systems that are always on.

While all- and four-wheel drive systems both have front and rear differentials, four-wheel drive systems usually feature a transfer case instead of a center differential. This part has a number of gears encased in it that split power to the front and rear axles, providing both sets of wheels with maximum torque.

Transfer cases also usually provide high- and low-range gearing. High range will allow you to drive at normal speeds, and is typically used for icy conditions or snow-covered roads. Using high range might also make sense on dirt roads, or in light off-road situations. Low-range gearing will limit your top speed, but it also provides a lot more power for more intense off-road conditions such as rock climbing, deep sand or muddy trails.

SS502 · February 23, 2019

12 hours ago, jrhaines2 said:

Am going to trade up from my 07 Denali and it looks like AWD is no longer available.Was the change in 2015?

Okay to answer your question and stop the back and forth about the petty differences in AWD and Auto on the K2, 2014 and newer have the Auto and as you’ve repeatedly pointed out it’s not AWD. So your OP is answered.

SS502 · February 23, 2019

2 hours ago, Mdsjohna said:

Both of the trucks you looked at had auto 4. Which is essentially the same as AWD in operation. This is obtained through the use of clutch plates in the transfer case which just happens to be how many AWD systems operate with a clutch.

Thank you!!! It’s not what he wanted to hear but thank you.

jrhaines2 · February 23, 2019

4 minutes ago, SS502 said:

Okay to answer your question and stop the back and forth about the petty differences in AWD and Auto on the K2, 2014 and newer have the Auto and as you’ve repeatedly pointed out it’s not AWD. So your OP is answered.

I'm not entirely sure of the operation and discussions where you learn are always a good thing in my book.

SS502 · February 23, 2019

11 hours ago, jrhaines2 said:

Thanks for the reply but that is 4wd not to be confused with AWD.

11 hours ago, jrhaines2 said:

An AWD system employs a front, rear and center differential to power all of the wheels. Sensors in those wheels take hundreds of readings per second. These sensors monitor each wheel's traction and the center differential increases and decreases power to each wheel as needed. This allows for fantastic control in all sorts of weather conditions and doesn't hinder your maneuverability.

At low speeds, AWD isn't as robust, so don't expect that raw power you'd get from 4WD. The same goes for pure towing power, which is why you mainly see AWD systems on cars and crossovers, not big trucks and SUVs.

Another difference between 4WD and AWD is that 4WD can be switched on and off. AWD is always on, so if you're seeking out top-tier fuel efficiency, then AWD might not be the best route to go. On the other hand, there are advantages to always having AWD engaged. AWD's ability to instantly adapt to changing road conditions, like ice and snow, without having to flip a switch takes human forgetfulness out of the equation. It's a much safer way to drive.

I will also add that an AWD vehicle does not have low range.

10 hours ago, jrhaines2 said:

Yes my 07 has AWD and is always on and I was looking at 15's and newer and seen the selector.I had an 02 and 07 Denali with AWD and AWD was only available on the Denali version with no other options available as far as AWD or selectable 4WD.

21 minutes ago, jrhaines2 said:

From Carfax.

All-Wheel Drive Basics

Let’s get a basic understanding of how all-wheel drive works before we dive into the configurations of this system. For a vehicle to have all-wheel drive, it has to be equipped with a center differential. A center differential is a set of gears that splits power from the transmission to the front and rear axles. Helping out the differential out are wheel sensors, which detect traction loss, wheel speed and other data points.

Now let’s look at how all of these components work together. Let’s say you are stopped on a snowy road and you decide to its time to move. You press down on the accelerator and power begins flowing to the wheels, but one wheel is spinning in the snow without gaining any traction on the road. This is where all-wheel drive comes into play. Sensors detect the loss of traction and begin feeding information to the vehicle’s computer. From there, the computer will adjust the amount of power going to each wheel, sending more to the wheels with better grip to get the vehicle moving.

All-Wheel Drive vs. Four-Wheel Drive

All-wheel drive is often interchanged with four-wheel drive in advertising, which causes many people to think they are the same thing. However, there are some key differences between all- and four-wheel drive systems. One of the big differences is how often these systems are on. All-wheel drive is running all the time, varying the amount of power to each wheel. Traditional four-wheel drive systems in many vehicles are classified as part-time systems, which means the vehicle operates in rear-wheel drive until four-wheel drive is selected by the driver. You’ll find part-time four-wheel drive systems in many trucks and off-road SUVs. However, certain models built by automakers such as Jeep and Land Rover have full-time four-wheel drive systems that are always on.

While all- and four-wheel drive systems both have front and rear differentials, four-wheel drive systems usually feature a transfer case instead of a center differential. This part has a number of gears encased in it that split power to the front and rear axles, providing both sets of wheels with maximum torque.

Transfer cases also usually provide high- and low-range gearing. High range will allow you to drive at normal speeds, and is typically used for icy conditions or snow-covered roads. Using high range might also make sense on dirt roads, or in light off-road situations. Low-range gearing will limit your top speed, but it also provides a lot more power for more intense off-road conditions such as rock climbing, deep sand or muddy trails.

You seem more knowledgeable than we are so thank you now we know.

jrhaines2 · February 23, 2019

5 minutes ago, SS502 said:

Thank you!!! It’s not what he wanted to hear but thank you.

Well it's pretty apparent they are 2 different systems.I travel a lot of back roads and hilly gravel roads and in the winter the AWD handles those types of roads better but I can get by fine with the standard 4x4.

SS502 · February 23, 2019

1 minute ago, jrhaines2 said:

Well it's pretty apparent they are 2 different systems.I travel a lot of back roads and hilly gravel roads and in the winter the AWD handles those types of roads better but I can get by fine with the standard 4x4.

And you’ve been pointing out the differences, not arguing you’ve pointed out the differences, thank you.

jrhaines2 · February 23, 2019

1 minute ago, SS502 said:

You seem more knowledgeable than we are so thank you now we know.

Only after doing some research.

ftwhite · February 23, 2019

2 hours ago, jrhaines2 said:

Well it's pretty apparent they are 2 different systems.I travel a lot of back roads and hilly gravel roads and in the winter the AWD handles those types of roads better but I can get by fine with the standard 4x4.

I disagree with you that 2014-2018 models with "Auto" are any different capability wise than 2002 or 2007 models with "AWD". These are marketing terms. The generall functionality of the transfer case in both implementations is the same. If you put your Silverado/Yukon/Suburban in Auto mode, it will be the same as "AWD" and provide teh same benefit. You only every need to use 2wd mode to same gas, and 4x4 mode for offroad or really poor traction scenarios. It expains it in the user manual and in the specifications of the transfer cases involved.

ftwhite · February 23, 2019

But, it does seem there is a difference after all, so I stand partially corrected. Seems like the 2007 AWD system might have been a BorgWarner 44-85 tansfer case, which is described as basically a center diff:

The Borg Warner 4485, is RPO NR3 transfer case it is a single speed, full-time, all wheel drive (AWD), transfer case. The transfer case provides power to axles, 40/60 torque divide, front/rear, full time through an external planetary type differential, which has two different sets of pinion gears. Both axles are constantly being driven for maximum traction in every conditions, have proven to provide slightly lower fuel mileage and more tire wear.

So, with Auto mode, you get a system that changes teh amout of power sent to the fronts based on loss of traction in the rear. In the older AWD system, you just get a fixed amout of power always being applied to front and rear via what sounds like an open diff in the place of a clutch based transfer case. That's how I read it at least.

Jacoby · February 23, 2019

Who gives a shit. So they have "auto" now instead of all wheel drive. Sounds like you're to lazy to reach up and turn a knob to me.

j-ten-ner · February 23, 2019

Auto 4x4 gives you the best of both worlds.

so long

j-ten-ner

jrhaines2 · February 23, 2019

7 hours ago, ftwhite said:

But, it does seem there is a difference after all, so I stand partially corrected. Seems like the 2007 AWD system might have been a BorgWarner 44-85 tansfer case, which is described as basically a center diff:

The Borg Warner 4485, is RPO NR3 transfer case it is a single speed, full-time, all wheel drive (AWD), transfer case. The transfer case provides power to axles, 40/60 torque divide, front/rear, full time through an external planetary type differential, which has two different sets of pinion gears. Both axles are constantly being driven for maximum traction in every conditions, have proven to provide slightly lower fuel mileage and more tire wear.

So, with Auto mode, you get a system that changes teh amout of power sent to the fronts based on loss of traction in the rear. In the older AWD system, you just get a fixed amout of power always being applied to front and rear via what sounds like an open diff in the place of a clutch based transfer case. That's how I read it at least.

I'm not sure about that.Like I said,I drive a lot of back dirt roads on hills that are rough and the AWD helps from keeping the rear from bouncing and losing traction and not sure how the auto 4wd would handle the situation but I will be fine with it.AWD would also be an advantage going around sharp corners as 4wd tends to try to push you straight.

jrhaines2 · February 23, 2019

11 minutes ago, Jacoby said:

Who gives a shit. So they have "auto" now instead of all wheel drive. Sounds like you're to lazy to reach up and turn a knob to me.

General Motors gives a shit.

Imcrazy · February 23, 2019

The current autotrac2 transfer case is an awesome system, the best on the market IMO... I really like how the auto setting performs is sloppy conditions or when doing a lot of turning but, if you need to throw down in some deep show the 4hi setting is nice to have too.. Even being in a snowy climate I don't use the 4x4 that often, having the G80 locking rear end plus really good M/S AT tires I get around pretty well in 2hi... Nice thing about this systems is that it saves on gas, I remember one of my buddy's mom got a denali yukon AWD and it really used some gasoline..