Slipping out of 2wd

[Roytveit]

I have swapped a LQ4 and 4L80E in my 2000 mod. Tahoe (from 5.3/4L60E).
I have a problem I cant figure out. When towing a trailer (6000 lbs), and running in low gear downhill (3rd, 2nd or 1st gear) in 2wd, somthing is slipping into neutral and making a virring sound. I have to put the shifter selector in drive and use the brake to stop the virring sound and get it back in gear. If I drive the car in 4Lo or 4hi it never slipp. If i put the car in 4auto, i can feel the front axle engage and disengage multible times down a hill.
I have tried two different transfer cases with the exact same result. I have now installed brand new 32 splines input gear and selector gear, but it still drop out. This never happened behind the 4L60E.
I can see there is a connection between the clutch fork and shifter fork in the NP246, maybe this is what prevent the slip in 4wd?
Very happy if anyone can share some Knowledge about this.

Thanks,
Roy Arild Tveit

 

[strutaeng]

You mean the engine braking (manual 2-1 band) is not applying or working?

I believe that only applies in Manual 2 (maybe also Manual 1?) When put in those 2 gear positions, engine RPM will increase and you should feel the vehicle slow down. Usually used when depending a steep grade.

 

[Roytveit]

You mean the engine braking (manual 2-1 band) is not applying or working?

I believe that only applies in Manual 2 (maybe also Manual 1?) When put in those 2 gear positions, engine RPM will increase and you should feel the vehicle slow down. Usually used when depending a steep grade.

Engine braking applies in 1st, 2nd and 3rd gear. When selecting 4wd for the transfer case everything work fine. When selecting 2wd for the transfer case, it looks like the sliding gear slips out of the input gear in the transfer case, and I loose the braking and the transfer case make a virring sound.

 

[rockola1971]

Engine braking applies in 1st, 2nd and 3rd gear. When selecting 4wd for the transfer case everything work fine. When selecting 2wd for the transfer case, it looks like the sliding gear slips out of the input gear in the transfer case, and I loose the braking and the transfer case make a virring sound.

Id be curious if you are 100% sure you put both units back together correctly.