4x4 system

[Loco-diablo]

Pardon my ignorance as this is my first GM truck. My old Toyota drive system had 2wd, 4high and 4low. My new z71 has 4auto? I assume this would be the setting to use when traveling around in New England snow? Or would the 4high setting be better? Without reading the manual, im assuming 4auto keeps the truck in 2wd until it senses slip?

 

Thanks

 

 

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[RyanbabZ71]

your assumption is correct. 4wd kicks in when it senses slippage. Do not use auto when the road is dry. I will occasionally run mine when it is rainign during the non winter months to keep the system "fresh"

 

Now go read your manual. There is valuable information in there

[newdude]

If there is snow/slush on the roads leave it in AUTO. If its deep snow say a good few inches unplowed, 4HI. Dry or rain leave it in 2WD.

 

AUTO mode. So, the front axle is engaged (locked). The transfer case does all the work if you will. If no slip is detected, all the power is to the rear, except for 0-5ft.lbs of torque to the front. The lack/limited power to the front, while the front axle is engaged, allows for no binding/popping of the front tires and suspension when turning. Now, once the truck detects the rear tires slipping, the transfer case has a clutch pack that when there is slip, allows for the engagement of power to the front axle, thus turning the truck in to 4HI until it deems that no more slipping is occurring.

[Loco-diablo]

I'm guessing that even in 2wd, traction will be much better than my old truck with the locking rear differential.. I've never had that either!

I'm not looking forward to winter but I hear the duratrac tires chew up the snow!

 

 

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[Sierra706]

Why does everyone in New England complain about winter and snow? That's the best part

 

 

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[Loco-diablo]

Why does everyone in New England complain about winter and snow? That's the best part

 

 

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Because it's too damn long. And heating my house is expensive!

 

 

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[duquephart]

Why does everyone in New England complain about winter and snow? That's the best part

 

 

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I thought it was the chowder.

[Loco-diablo]

 

 

I thought it was the chowder.

Ha ha! You haven't lived until you've had a big bowl of NE clam chowdah!

 

 

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[Silverado Steve]

Waiting for all the "if you need 4 auto on clean roads you can't drive" to come out of the woodworks.

['17 Sierra]

If there is snow/slush on the roads leave it in AUTO. If its deep snow say a good few inches unplowed, 4HI. Dry or rain leave it in 2WD.

 

AUTO mode. So, the front axle is engaged (locked). The transfer case does all the work if you will. If no slip is detected, the power split is 5% to the front, 95% to the rear. The 5% power to the front, while the front axle is engaged, allows for no binding/popping of the front tires and suspension when turning. Now, once the truck detects the rear tires slipping, the transfer case has a clutch pack that when there is slip, allows for the engagement of power to the front axle, thus turning the truck in to 4HI until it deems that no more slipping is occurring.

 

Sort of. The front axles are always turning (locked) even in 2WD. There are no locking hubs. It's the front drive shaft that engages in Auto 4WD so the transfer case is synchronized front/rear and the clutch pack allows for slippage when turning.

[newdude]

Sort of. The front axles are always turning (locked) even in 2WD. There are no locking hubs. It's the front drive shaft that engages in Auto 4WD so the transfer case is synchronized front/rear and the clutch pack allows for slippage when turning.

 

 

The front axle actuator locks in AUTO as it does in 4HI. This actuator unlocks in 2HI.

 

The clutch pack in the transfer case does all the work sending power to the front wheels. I mentioned that talking about the power split when no slip is detected.

The Magna Powertrain (MP) model 3023/3024 RPO NQH transfer case is a 2 speed automatic, active transfer case (ATC). The MP 3023/3024 ATC provides 5 modes, Auto 4WD, 4HI, 4LO, 2HI and NEUTRAL. The Auto 4WD position allows the capability of an active transfer case, which provides the benefits of on-demand torque biasing wet clutch and easy vehicle tuning through software calibrations. The software calibrations allow more features such as flexible adapt ready position and clutch preload torque levels. The technology allows for vehicle speed dependent clutch torque levels to enhance the performance of the system. For example, the system is calibrated to provide 0–6.78 Y (0–5 lb ft) of clutch torque during low speed, low engine torque operation, and predetermined higher torque for 40 km/h (25 mph) and greater. This prevents crow-hop and binding at low speeds and provides higher torque biases at higher vehicle speeds, in order to enhance stability.

 

During normal driving situations, the transfer case can operate in the Auto 4WD mode. In the Auto 4WD mode, the transfer case shift control module monitors rear wheel slip speed, based on the inputs from the wheel speed sensors and/or vehicle speed sensor. When the vehicle experiences a rear wheel slip condition, the transfer case shift control module sends a pulse width modulated (PWM) signal to an electronic motor, which is the transfer case 2/4 wheel drive actuator assembly. This actuator rotates the transfer case control actuator shaft, applying a clutch. The clutch is designed to deliver a variable amount of torque, normally delivered to the rear wheels, and transfers it to the front wheels. Torque is ramped up to the front wheels until the front wheel speed sensor matches that of the rear wheel speed sensors and/or vehicle speed sensor. Torque is ramped down to the front wheels. The process would repeat if rear wheel slip is detected again.

 

[Brian S.]

Pardon my ignorance as this is my first GM truck. My old Toyota drive system had 2wd, 4high and 4low. My new z71 has 4auto? I assume this would be the setting to use when traveling around in New England snow? Or would the 4high setting be better? Without reading the manual, im assuming 4auto keeps the truck in 2wd until it senses slip?

 

Thanks

 

 

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I leave it in Auto 4 a fair amount in the winter. My dad leaves it in Auto 4 all winter. I have a friend who puts on a lot of miles and leaves it in Auto 4 year round.

 

The "does Auto 4 burn out transmission" debate can be found in a few threads here if you search it.

 

The manual says nothing about driving in 4 auto potentially damaging the transmission, but it does warn about not using 4h/4L on dry pavement. For my part, I've towed the boat home a couple hundred miles in Auto after forgetting when using it to get up the boat ramp, and left it in 4 auto in the summer for weeks for the same reason.

 

YMMV

 

I only use 4 Auto, and that includes driving on frozen snow covered lakes and down the unplowed dirt/gravel road to my cabin. My guess is living in the Boston area you can forget the other settings exist.

 

['17 Sierra]

The front axle actuator locks in AUTO as it does in 4HI. This actuator unlocks in 2HI.

 

The clutch pack in the transfer case does all the work sending power to the front wheels. I mentioned that talking about the power split when no slip is detected.

 

That's right. And the clutch pack is locked in 4HI (and 4LO). But the axles are always engaged up to the front diff; 4HI Auto 4WD, LO and 2WD. Dodge keeps their front drive shaft engaged and basically operates like selectable hubs that are locked all the time.

[Knightfall]

Not trying to hijack the thread, but I like the more technical discussion regarding 4x4 going on here. A question I've always had was, what "replaced" having locking hubs? Electronic actuators that did it or just leaving the front axle engaged?

[truckguy82]

Pardon my ignorance as this is my first GM truck. My old Toyota drive system had 2wd, 4high and 4low. My new z71 has 4auto? I assume this would be the setting to use when traveling around in New England snow? Or would the 4high setting be better? Without reading the manual, im assuming 4auto keeps the truck in 2wd until it senses slip?

Thanks

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The truck has 2wd, awd, 4wd hi, and 4wd lo. A tradditional 4x4 and a traditional awd vehicle each have their advantages and disadvantages, we can basically reap all the benefits of both systems without the downsides since the mode is selectable. On top have having all that, it's very stout and can handle quite a bit of abuse and hp. In short, it's ****ing awesome.