I have owned several 4X4s of various makes and models and they all have the same warning DO NOT DRIVE ON DRY ROADS WHEN 4X4 ENGAGED! my Question is simple how does the truck know the road is dry and not wet? I'm told it is because its hard on the hubs, is this correct and what would cause the damage?

 

In lower traction conditions (sand, gravel, wet roads, snow, etc), the tires are allowed to slip a bit.

Now part-time 4wd is what is not recommended for use in dry conditions. The reasoning for not running in 4wd is because there is not a differential in the transfer case and 1 wheel on each axle will always rotate at the same speed. When turning, no two wheels follow the same arc, meaning that they will ALL be rotating at different speeds. When in 4wd and in high traction situations, this will cause binding in the drivetrain and could break things if done routinely.

Full-time 4wd is made to be just that and will not bind up when on dry pavement, but again, it is not as smooth as what a true AWD system is.

 

Now that makes sense I have heard all kinds of reasons and that makes the most sense, thanks for clearing that up!

 

Nice job swart.

 

yep very nice.....answered my question b4 i asked it

 

LOL Thanks guys. I was looking for a website that had pictures explaining it, but couldn't find it. I could have sworn that it was on the 'How Stuff Works' website, but a few search terms didn't yield the proper results... Oh well.

 

Searching on HowStuffWorks is dificult at best. I aways have the best results by going to google, then type in "howstuffworks 4x4" Finds it everytime, this time 2nd link in the list.

How 4x4 works

 

Nope, not the same as I was looking for. It was a pictorial & text explaination of why not to use a Part-Time 4wd on dry, high traction conditions and showed the differences between part-time, full-time, and all-wheel-drive applications with little videos showing each (much like the how-stuff-works page), but specifically during turning with the 3 different systems.

 

Not sure if this is the page you were talking about, but I found it to be quite informative and touches on most of the points previously mentioned.

http://www.4x4abc.com/4WD101/def_turnpart.html

 

Yeah that is something very similar.