2002 Tahoe z71 rear diff question

[OR VietVet]

I am in Eugene and spend time in Florence at coast. I am hardly ever, rarely, in 4wd. In 4wd will steer harder and bind on dry pavement.

 

[Mudsport96]

The only 4wd car I’ve had before was a G-wagon with lockable TC, front diff and rear diff. So that’s basically what I’m used to. And this 2wd/4wd on the Tahoe means the TC will lock (bad way of explaining since there is no TC diff but) when I engage 4wd, right? So it’s basically like driving the G with the TC diff locked and that’s what’s causing the (imo quite brutal) binding when being in 4wd, correct?

Yes exactly. The Gwagon has a different awd/4wd system than these vehicles. You do not want to use 4wd unless it is absolutely needed. These have a positive engagement TC all the time. They don't have a lockable center diff.
Very old versions of these had the 4hi and 4hi lock cases. But not any more, once you are in 4wd you are locked.

 

[Marky Dissod]

You do not want to use 4WD, unless it is absolutely needed.

Note that I've also an '02 Tahoe Z71 4WD; see my sig.

I won't consider pressing 'Auto 4WD' unless it's raining pretty hard.
I won't consider pressing '4WD High' unless it's snowing.
I won't consider pressing '4WD Low' unless '4WD High' isn't enough to get me unstuck.

 

[rockola1971]

Note that I've also an '02 Tahoe Z71 4WD; see my sig.

I won't consider pressing 'Auto 4WD' unless it's raining pretty hard.
I won't consider pressing '4WD High' unless it's snowing.
I won't consider pressing '4WD Low' unless '4WD High' isn't enough to get me unstuck.

Auto 4wd arms 4wd. The Tcase is then magnetically engaged into 4wd by locking the clutches when the PCM sees different wheel speeds that would indicate wheel slippage. So even though its in Auto4WD, it is not in 4wd until all the other magic mentioned happens.
Our 4wd system (NP246/NP246E) doesnt much care about being in 4wd in a straight line. It is in turns on dry pavement when you get wheel hop and binding in 4wd.
Ive never used 4wd low on the road because it is geared way low! I have put my vehicles in 4wd low just playing around off road and thats how I found out exactly how low it is geared.

 

[Marky Dissod]

Auto 4WD arms 4WD.
The Tcase is then magnetically engaged into 4WD by locking the clutches when the PCM sees different wheel speeds that would indicate wheel slippage.
So even though it's in Auto 4WD, it is not in 4WD until all the other magic mentioned happens.

This is mostly true, but there's a caveat:
Being in Auto 4WD gets slightly worse MpG than 2WD, EVEN if it turns out to never have actually driven the front wheels.
Still, I totally get your point.

Our 4WD system (NP246/NP246E) doesn't much care about being in 4WD in a straight line.
It is in turns on dry pavement when you get wheel hop and binding in 4WD.

How much power would be needed for AWD to be an advantage in drag racing over RWD? ...

I've never used 4WD Low on the road because it is geared way too low!
I have put my vehicles in 4WD Low just playing around off road and thats how I found out exactly how low it is geared.

There is a distinct possibility that I may never need to use 4WD Low, and I will not be sorry if I never do.

 

[Mudsport96]

Still, I totally get your point.How much power would be needed for AWD to be an advantage in drag racing over RWD?

Well I think the current record holder for a 2wd tahoe is high 9s...so alot.

 

[Marky Dissod]

... think the current record holder for a 2WD tahoe is high 9s ...

Then I guess my question is, would his Elapsed Time improve with 4WD?
His 60Ft time would likely improve, but once it hooks up, 4WD is probably just robbing power going forward.

 

[Sam Harris]

Is it possible someone welded your rear diff..? Sounds possible, based on your description. Either that, or the G80 has a problem.

 

[houstontaylor]

In the recent past my tahoe would sometimes stick in 4wd and it turned out to be a bad transfer case module under the dash. I got the service 4wd message also.