Driving in 4x4 auto?

[MikeNH]

Nope. Front diffs don't lock on these trucks. Never have. The t case locks and if you have the G80, the rear night but that's it.

[Silverado-Hareek]

Nope. Front diffs don't lock on these trucks. Never have. The t case locks and if you have the G80, the rear night but that's it.

Is the front diff on these trucks different from the gmt900?

[MikeNH]

Is the front diff on these trucks different from the gmt900?

Nope. Slight mechanical differences with how 4x4 is turned on aside, what is inside the front of a 2014 is essentially the same as a GM 1500 from 1988 when they first started with independent suspension. The binding front to rear comes into play because the axles are at different points in the turn and require different speeds but they're being forced the same power. I've driven a Jeep with the front locked and even on loose surfaces turning tight was much different than a normal 4x4 bind you see on dry roads.

[Isriam]

ive replaced 3 transfer cases on my 07 tahoe with "auto" 4wd. It wasn't driven by me, but the person driving it didn't understand auto didn't actually mean all the time. Now we leave all vehicles in 2hi unless its snowing and had no issues.

 

fyi 2012 denali had AWD which of course is way different than auto 4wd.

[Silverado-Hareek]

Nope. Slight mechanical differences with how 4x4 is turned on aside, what is inside the front of a 2014 is essentially the same as a GM 1500 from 1988 when they first started with independent suspension. The binding front to rear comes into play because the axles are at different points in the turn and require different speeds but they're being forced the same power. I've driven a Jeep with the front locked and even on loose surfaces turning tight was much different than a normal 4x4 bind you see on dry roads.

 

So you're saying the binding still occurs in turns but it's the transfer case, not the front differential, that's the culprit? I guess we're saying the same thing, just pinpointing the location of the binding differently. The issue should still be the front left and right tires rotating at different rates in turns and opposing the force of the axle which is downstream of the front drive axle and transfer case. Maybe the transfer case is where the binding occurs but the reason for the binding is the difference in rotation rates of the front wheels fighting back against the drive line.

[MikeNH]

All the tires spin at different speeds in a corner. So when they're forced to split power 50/50 front to rear things bind up. Only a handful of factory vehicles have a front locking differential and it's always a manual activation as it absolutely ruins steering ability and it's tough on front end parts.

[kstruckcountry]

Since the front axle is an open diff once engaged, that isn't where most of the binding comes from. It's primarily the difference in speeds between the front and rear axle. Which is why there is no binding in 4x4 Auto, because when it's not sending power to the front, the drivelines are free to rotate at different speeds.

[thetruck454]

I disagree here. The issue is the speed differential between the front left and right tires when turning because the front axle is spinning at a constant rate but when you turn say to the right, the left tire rotates more than the right tire. This isn't a problem under normal driving but when you are in 4wd and the truck is sending power to the front axle and wheels, binding occurs on dry payment when turning because the tires are rotating at different rates from each other while the front axle is driving both of them at a constant rate. That's why you have to be on loose terrain so the right tire in this scenario can slip and not oppose the left tire, and vice versa when turning to the left.

The front differential is open so there can be no binding between sides. The binding comes from the front and rear axle wanting to spin at different speeds while being locked together by the 4x4 tcase. On the awd trucks the front axle doesn't even have the disconnect so its always "locked" and you don't having binding. This is due to the awd tcase allowing slip.

[Silverado-Hareek]

The front differential is open so there can be no binding between sides. The binding comes from the front and rear axle wanting to spin at different speeds while being locked together by the 4x4 tcase. On the awd trucks the front axle doesn't even have the disconnect so its always "locked" and you don't having binding. This is due to the awd tcase allowing slip.

 

Ok I understand now thanks for the explanation.

[Spurshot]

When it used to rain in Socal, many years ago, I would put my GMT900 in Auto and drive to work. Once in a while, I'd stand in it from a light when next to a gearhead type.

[Spurshot]

NEVER NEVER NEVER NEVER DRIVE IN 4 Auto all the time unless you are on loose terrain that may require 4 wheel drive!!!!

 

...

Your grade school English teacher would never let you get away with that all the time.

[Silverado-Hareek]

Your grade school English teacher would never let you get away with that all the time.

What?

 

Obviously you're one of "those people" that gets their jollies pointing out grammatical errors on the internet, but I think you're missing something.

 

Update: oh you must be referring to my omission of "of" as it should have read "all OF the time." My apologies. I'll be sure to correct this for future postings so that your reading experience is no longer negatively affected by my grammatical errors.

[MikeNH]

Guys we can debate 4WD systems but we need to be respectful. No need to call out grammatical errors, real or otherwise.

[Spurshot]

What?

 

Obviously you're one of "those people" that gets their jollies pointing out grammatical errors on the internet, but I think you're missing something.

 

Update: oh you must be referring to my omission of "of" as it should have read "all OF the time." My apologies. I'll be sure to correct this for future postings so that your reading experience is no longer negatively affected by my grammatical errors.

Just yankin your chain... But I did miss exactly what you were saying. Did you mean not to leave it in Auto for a long period of driving or were you saying not to use it in Auto on pavement?

[Spurshot]

Well, I couldn't stand it...I took today off work and was BBQing for the block party tomorrow, but this question about Auto 4wd was nagging me. I went to the truck and got the manual. I couldn't find mention of Auto in my short browse of the manual.