4HI vs. Auto 4 Wheel

[puckhead]

So i have heard some people say that driving on pavement with 4 wheel drive engaged is bad. I thought that as long as you dont switch in and out on pavement you will be fine. It has started to snow, then melt, and is now a frozen sheet of ice on the roads around here. I have been using 4HI. SHould I use Auto or no? Im asking because some of the roads are dry and others are still frozen. Thanks for the help! Hope i made it kinda clear.

 

[ac1975]

To my understanding, driving in 4HI on dry pavement and turning is bad. For the conditions you mentioned, I'd prob be in auto. 4HI when there is snow everywhere. The owner's manual say's to use 4HI for plowing and severe conditions. 4LO for extreme.

 

[puckhead]

Alrighty thanks. Didnt know about the turning part, but i guess i do know! For the Auto, does it slip like 4HI when going from 2wheel to 4wheel? Wouldnt that be just as bad as putting it in and out of 4HI? Thanks again!

 

[Nickleahy23]

in auto the shaft is always spinning to the front differential..so it engages alot easier..lately ive just been drivin in 2hi and then switchin to 4hi when i need it..you can drive on pavement no problem in 4hi, its just that when turning you will get some tire chatter..

 

[puckhead]

Alrighty, thats what I thought was happening. I just thought it was because i was turning sharp at a slow speed. Thanks for the help and thoughts guys!

 

[Yuke2K]

Nick sorta hit on this already, but I'll explain a little further.

In 2-Hi, you're strictly in two-wheel. The shaft to the front diff is disengaged so it's not even spinning.

In Auto, you're still primarily in two-wheel. The difference though, is that the shaft for the front diff is engaged. It's not POWERED all the time, but it's engaged so it's spinning. This allows the computer to apply engine power to the front wheels when it senses tire slippage, and since the shaft is already engaged, it can do this pretty seamlessly (hence the reason you don't feel that *clunk* when it switches in and out).

In 4-Hi, the shaft is engaged and under full engine power all the time. Same for 4-Lo but running off different gearing in the T-case so you get lots more torque...but you can't run your rig very fast.

Hope that clears up the mystery a little for you. :thumbsup:

 

[Rollin Thunder]

in my 06 yukon and on my 03 silverado I notice when I run in auto it kinda makes a funny noise. I thought somthing was wrong, but I guess its normal, It sounds like AT tires humming, But only does it in auto 4x4. I use true 4x4 only when in sand, mud, and if i ever see it, snow. Other wise I use auto 4x4 when ever the roads are slick. Even in rain.