Smart Trak Operation Question

[MNSubbie]

Maybe someone who has a NP-136 Transfer Case in their Bravada could answer this for me. I understand the process for how the Transfer Case determines when to lock up into 4 wheel drive.

But I want to know how it determines when to UNLOCK?? It is based on time or what?

[MT-2500]

Originally Posted by MNSubbie

Maybe someone who has a NP-136 Transfer Case in their Bravada could answer this for me. I understand the process for how the Transfer Case determines when to lock up into 4 wheel drive.

But I want to know how it determines when to UNLOCK?? It is based on time or what?

I do not have one but work on them.

What year make and model?

Shifting into 4W locks transfer case into 4W.
In 4W the transfer case applies clutch pack pressure as needed from any wheel slippage to keep front and rear wheels turning even.
All done automatic by transfer case computer
All computer controlled.

[MNSubbie]

Thanks MT.......my Bravada is a 2000

[MT-2500]

Originally Posted by MNSubbie

Thanks MT.......my Bravada is a 2000

You are welcome.
In 4W the torque to front and rear drive shafts is applied by a variable clutch inside transfer case.

Controlled by a electric shift motor.
Within 70 milliseconds after wheel solo reading from wheel speed seconds the shift motor applies pressure to the front or rear drive shaft as needed.
The transfer case control module rechecks and adjusts it ever 10 seconds as needed.

The transfer case uses special GM auto track fluid that should be changed ever so often.
Check owners manual or service manual for change mileage.

If not change when should be the variable clutch can give expensive problems.
Like a jerking on the road and or not working or holding it in 4W.

Good luck

[MNSubbie]

Hey MT, I have another Smart Trak Question for you. Just bought this vehicle and I am not used to the xfer case making my choices for me. Gotta get used to it I guess, and determine if this one is working properly.
I noticed when working on the front suspension this morning, that the front axels and driveshaft do not spin freely. They are defintely NOT in a nuetral mode, like I thought they'd be. I can turn them, but it obvious I am turning against the clutches in the Transer case. Is this normal----and then the transfer case automatically increases the pressure in the clutches when needed?? Or is this thing supposed to be free wheeling until it needs some extra traction??
(hope I made sense in this explanation??!!) (the tag on the case says its a NP136)
Your insight would be appreciated

[MT-2500]

Originally Posted by MNSubbie

Hey MT, I have another Smart Trak Question for you. Just bought this vehicle and I am not used to the xfer case making my choices for me. Gotta get used to it I guess, and determine if this one is working properly.
I noticed when working on the front suspension this morning, that the front axels and driveshaft do not spin freely. They are defintely NOT in a nuetral mode, like I thought they'd be. I can turn them, but it obvious I am turning against the clutches in the Transer case. Is this normal----and then the transfer case automatically increases the pressure in the clutches when needed?? Or is this thing supposed to be free wheeling until it needs some extra traction??
(hope I made sense in this explanation??!!) (the tag on the case says its a NP136)
Your insight would be appreciated

What year make and model?
You may need to test it with all 4 wheels jacked up and engine running.
There may be some drag but if you can turn it some there is not much..
In 4 wheel auto on the road the front clutch to front drive shaft should release if no wheel slippage.