Bad vibration at 80-95km when coasting

[Peakey91]

I own a 2006 Silverado 2500 HD, (6L Gas) and when I am travelling at around 80-95km I get a terrible vibration in my 4wd gear selector. I only get the vibration when im coasting not accelerating. Usually when I'm going down hill it's the worst. As soon as I put my foot on the gas it almost makes a snapping noise and the vibration goes away. It's been getting a lot worse. I needed a bunch of work done so I did my tie rod ends, my pitman arm, LH hub/wheel bearing, front drive shaft u joints, (about to do rear shaft u joints) I also noticed trouble shifting into 4wd when my front end was lifted off the ground it made a loud snapping noise. Can't remember specific details about that though. I wonder if my transfer case is on the way out

[davester]

u-joints can do this (and the vibration gets transmitted through the transfer case to the shifter...)

 

possibly the output shaft bushing of the transfer case (you could check to see if you can move the yoke a bit...)

 

you might also crawl under the truck and see if any oil is present on the back of the transfer case and to check it's fluid level, as the original case has a design flaw where the internal oil pump will rub a hole in the case, allowing the fluid to escape, and then the TC gets ruined). You can find out more by googling "gm pump rub" or "gm pump rub fix". And if you don't know if your TC has a fix installed, I recommend installing one before it rubs a hole in your case.

[wally9]

I own a 2006 Silverado 2500 HD, (6L Gas) and when I am travelling at around 80-95km I get a terrible vibration in my 4wd gear selector. I only get the vibration when im coasting not accelerating. Usually when I'm going down hill it's the worst. As soon as I put my foot on the gas it almost makes a snapping noise and the vibration goes away. It's been getting a lot worse. I needed a bunch of work done so I did my tie rod ends, my pitman arm, LH hub/wheel bearing, front drive shaft u joints, (about to do rear shaft u joints) I also noticed trouble shifting into 4wd when my front end was lifted off the ground it made a loud snapping noise. Can't remember specific details about that though. I wonder if my transfer case is on the way out

My guess would be a slip yoke going bad. Does your drivw shaft's slip yoke have any slack at all?

 

Sent from my SAMSUNG-SM-N920A using Tapatalk