When in 4 wheel drive it makes a rough vibration in the front end at random. It comes and goes and immediatly stops if I let off the gas. Also when say backing or pulling in a parking spot or anytime I have to turn the wheel all the way the car immediatly slows down like its getting alot of resistance then resumes normally once the wheel is turned a bit straigher. It does not happen during normal driving only when the wheel is turn nearly all the way either direction. I'm more worried about the vibration. I've just gotten an oil change and they said the differential fluid is clean and full. So thats past the technical knowledge I have. I mostly only use the blazer for towing the camper in the summer and for bad snow in the winter since my normal car blows in the snow. The trans was replaced about 15k miles ago.

 

can you feel the vibration thru the floor boards or steering wheel

 

It sounds like you've got a bad u joint in the front end. $20, fairly easy to change depending on your level of mechanical knowledge. The tightness when turning is driveline binding and is normal, try not to make tight turns when in 4wd, especially when in 4lo. It could possibly be something in the front end, but you'd probably hear some noise, typically gear whining or grinding.

 

The vibration effects the entire front end. Feels like i'm driving across those things they cut in the road like before a toll both but worse. And only from the front end.

 

But you're saying only in 4wd correct? If so, I still say front ujoint, if it does it all the time, check wheels bearings.

 

I would agree that the front driveshaft is likely the source of the vibration. It could be the front u-joint or I have seen the rear joint go bad as well. The rear joint is more of a CV joint than universal.

 

Driving home today in Ohio's horrible weather I had to go 4 wheel quite a ways cause stupid people can't drive up hills without stopping. So I noticed that It mostly vibrates when accelerating right around 40mph. Didn't really get to go past that. But as soon as I let off the gas I can stay at and above 40 without the vibration, its just right as I hit 40 during acceleration.

 

I have the exact same problem. someone please offer a fix for this.

going past 40mph in 4wd shackes the whole front end of the car really badly and makes turning almost impossible.

also when i engage 4wd i dont hear a thud under the car, but i know its engaged cuz front and back wheels spin. but there is a huge thud when i put the car back into 2wd.

 

Guys, we've offered up some suggestions, check the u-joint at the front differential. If it's good, check the rear joint at the transfer case. Like Swart said, most of these trucks it's a CV style joint at the TC.

To check the front one, get yourself a 7/16 wrench and a decent sized flat blade screw driver. Unbolt the saddles on the front u-joint, make sure Tcase is in 2wd so you can spin it to get to all the bolts. Use the screwdriver to keep the shaft from spinning while you're breaking them loose by sticking it up through the shaft by the joint.

Now use the screwdriver to slightly pry the joint back so it pops out of the front yoke. BE CAREFUL not to let the two caps drop off. There are needle bearings in there. You're checking to see if it has free play. If you can't swivel it back and forth easily, it's shot. If there is resistance to it replace it. Carefully remove the caps from the other two ends and make sure there is grease in there and no rust, etc, again be careful not to drop any needle bearings out. If it looks good put it back together. If not, repost here and we'll tell you how to change it out.

 

if i put my car on a jack i there is some play on the front passanger side tire to turn it left and right by hand. not much, but there is definaly some play. is that normal?