hey guys I have a 1999 ram 1500 4x4 318, today the roads were a little slick so I thought i would try the 4x4 , when i reached the highway I switched from 4hi to 2 hi on the fly At about 45 mph, When the 4x4 disengaged there was a pretty loud crunch from under the truck, Any ideas what that noise was, in my owners manual it stats you can shift on the fly up to 55mph, thanks.

 

mine does it too while moving...i usually pay it no mind, nothing falls out and the truck keeps moving so oh well

 

Best bet would be to not use 4wd on pavement, wet or dry. The 4wd is designed for loose, low traction surfaces such as gravel, mud, sand, etc but your truck will generate enough traction under normal driving conditions that even on wet, slick pavement, using 4wd does little but add undue strain on your driveline. You'll be replacing your U-joints every six months otherwise.

 

Awww horsesh*t ... we gonna start this again? I've been using 4hi on wet pavement for as long as I've owned 4x4's ... haven't had to replace one driveline component ... ever.

 

what exactly happens when the 4 hi is disengaged?

 

Look here for information on how our CAD system works: http://www.4x4wire.com/dodge/tech/solid_axle_cad/

 

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I'm not gonna get started but I agree with TMS.

Anyways, the clunk is just the CAD disengaging while moving that fast. Probably not gonna hurt it since the owners manual says its alright. I usually make sure I'm coasting when I kick it out so theres not really any force being applied to the CAD. If your on the gas theres gonna be force on the shafts keeping them spinning, then you pull the fork out of the 2 shafts when you disengage and it makes a clunk.

 

When you say "coasting" do you mean "floating"? I give it just enough gas to maintain speed (throttle's just cracked) ... neither accelerating nor decelerating. I figure that puts the least amount of torque on the system.

 

That'd work too probably, I take my foot off the gas completely though. Probably just preferance.