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4wd operation information

marine6680

By marine6680
in Engines & Drivetrain

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marine6680 New Member

marine6680

Posted
Posted

Looking for some technical information regarding the 4wd system in my '16 LTZ Z71.

I like knowing what the truck is doing when the system is engaged.

 

So far, I think I have a bit figured out.

 

Being an electronic system, the transfer case uses clutch packs to engage 4wd modes rather than meshing gears. This is how they accomplish a smooth shift on the go 4wd, and what allows the auto mode to work smoothly.

The rear diff is auto locking, and will lock up when slip is encountered. (left to right) Normally it acts more like an open diff.

In "auto" mode, the transfer case is sending power to the rear diff, and when it senses slip, it activates the (I'm guessing electrically controlled) clutch inside the transfer case to send power to the front diff.

The front diff has an "actuator" that engages the diff somehow... not 100% sure the technical details, but I get the sense that the front diff is decoupled left to right, its not even acting like a simple open diff, the left and right axles are independent unless the actuator is engaged... Is that right?

This front diff actuator must engage for 4wd use. In auto mode, it is engaged full time, but the transfer case is not sending any power to the front diff until needed. During normal 4wd mode, the actuator is engaged full time, with power being fed from the transfer case.

 

I am not sure what kind of diff the front is... Is it an open or some type of limited slip, or auto locking... A limited slip or auto locking seems most useful and likely to be what it is... but I could be wrong, I have seen trucks with an open front diff, and my truck could be no different.

 

To me, having the front wheels receiving power, but only the front wheel without traction getting that power seems like you might as well not even have 4wd. If you have a front tire and rear tire on ice while stopped, seems a 4wd system without a limited slip diff in the rear and front, or auto locking or manual locking, would just sit and spin... Or what if only one front tire had any traction... same thing.

My main question about the technical details mostly fall around the front diff, what type it is, and what the actuator does... But if I have any of the other details wrong, let me know.

 

Thanks

HondaHawkGT Senior Enthusiast

HondaHawkGT

Posted
Posted

Looking for some technical information regarding the 4wd system in my '16 LTZ Z71.

I like knowing what the truck is doing when the system is engaged.

 

 

So far, I think I have a bit figured out.

 

Being an electronic system, the transfer case uses clutch packs to engage 4wd modes rather than meshing gears. This is how they accomplish a smooth shift on the go 4wd, and what allows the auto mode to work smoothly.

The rear diff is auto locking, and will lock up when slip is encountered. (left to right) Normally it acts more like an open diff.

In "auto" mode, the transfer case is sending power to the rear diff, and when it senses slip, it activates the (I'm guessing electrically controlled) clutch inside the transfer case to send power to the front diff.

The front diff has an "actuator" that engages the diff somehow... not 100% sure the technical details, but I get the sense that the front diff is decoupled left to right, its not even acting like a simple open diff, the left and right axles are independent unless the actuator is engaged... Is that right?

This front diff actuator must engage for 4wd use. In auto mode, it is engaged full time, but the transfer case is not sending any power to the front diff until needed. During normal 4wd mode, the actuator is engaged full time, with power being fed from the transfer case.

 

I am not sure what kind of diff the front is... Is it an open or some type of limited slip, or auto locking... A limited slip or auto locking seems most useful and likely to be what it is... but I could be wrong, I have seen trucks with an open front diff, and my truck could be no different.

 

To me, having the front wheels receiving power, but only the front wheel without traction getting that power seems like you might as well not even have 4wd. If you have a front tire and rear tire on ice while stopped, seems a 4wd system without a limited slip diff in the rear and front, or auto locking or manual locking, would just sit and spin... Or what if only one front tire had any traction... same thing.

 

My main question about the technical details mostly fall around the front diff, what type it is, and what the actuator does... But if I have any of the other details wrong, let me know.

 

Thanks

Auto 4WD - Transfer case sends a little power to the front all the time (approx 10% is the most common claim I have read). Reacts extremely fast to send more power to the front when the wheel speed of the two wheels is less than the equivalent speed of the output shaft sending power to rear axle.

4WD HI/LOW- Transfer case is locked in and power is split 50/50 like a standard 4WD system.

 

The front diff is an open diff all the time. Rear diff is a locking diff that engages automatically via a governor mechanism. It engages when there is a 100 RPM differences between the left and right rear tires. It will unlock when you reach roughly 30 MPH or stop and move in reverse for a short distance.

slee3247 Enthusiast

slee3247

Posted
Posted

If these trucks are the same as the earlier ones, there's a solenoid that acts as a front axle disconnect. Basically, it's a solenoid that pushes a synchroniser assembly onto the axle which has matching teeth. This locks the axle to the differential. However, the front differentials are open style on these trucks.

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