Been having a vibration that starts about 70mph and gets worse at higher speeds.. It is a real fast vibration to fast to be a tire. But had them balanced again just incase... Didn't help.

So I thought U-Jointd.... after jacking the back end up off the ground and grabbing the driveshaft to move it looking for slop in ujoint .. I realized the front drive shaft was turning with the rear. After some more evaluation I realize that the front drive shaft is staying engaged all the time.. The lights on the dash for the 4x4 work fine and it does go in 4 when ask to.. but never releases the front drive shaft? I even went to a used car lot and crawled under 3 other Z71's to make sure it was supposed to spin free when in 2x2.

Pretty sure that is where my vibration is coming from since the front drive shaft probably wasnt meant to spin at 70mph.. Oh by the way Ujoints seem fine but there was a little play in the front slip joint..

a mechanic told me that he thought the transfer case was going to have to be rebuilt and it would cost 500 to 800 bucks.. I just dont see it... Any ideas or suggestions? Thanks...

 

What year is your truck?

 

geez forgot to mention the basics.. sorry.. It is a 2000 with the 5.3 engine. Now has about 74,000 miles..

 

Been outside tinkering with it today.. Transfer case is full of fluid and when you select the 4x4 or 2x4 buttons you can hear both selonoids making noise. Since I hear the noise and the lights on the buttons are working ok I assume the selonoids are working ... Is that a fair assumption???

 

Took the selonoid off the transfer today.. tried shifting the transfer case manually goes into 4x4 low ok and goes into 4x4 high but wont shift into 4x2 at all.. not even manually.. so guessing the transfer case is the problem..
Bolted it all back together and traded it off for a Suburban.. PROBLEM FIXED.. LOL... "I HOPE"..