98 blazer 4x4 automatic .I have got a problem with front drive axles / differential . I have a vibration going on at all speeds, but at around 60-70 mph it gets really bad . It kind of sounds like a rotational noise/vibration like a bad tire or bearing, but at lower speeds you can hear it make more of a knocking around noise. To me it sounds like a CV axle with a wore slap out joint. I let a front end shop look at it, and he said it needed 4 -ball joints, shocks,idler,pitman, f.r. wheel bearing. I went and replaced everything except shocks, and it didnt change. So i swaped new bearing to f.l. side, no difference. So now where im at is Im sure its coming from R or L+R driveaxle or the differential, but im not to sure about which one. How would I check to see if the front differential is disengaging all the way? I should also mention that when you drive in 4 hi it doesn't vibrate as bad and the knocking around noise is pretty much nothing. But when you go back into 2 hi , driving it will vibrate and , knock around .

 

Have you checked the cable to make sure its not frozen? What you can do is once you shift out of 4x4 (going slow or at a stop) put the truck in reverse and go back a little bit.. do you hear/feel it disengage?

 

yea I think think it does disengauge at the transfer case. because it is allways inthe right gear ( 4hi - 2 Hi ) and shifts in and out without any loud bangs. It doesn't make any noise backing up when you take it out.What I was wondering is if the front differential could be part of the way engaged when in 2 hi, and wheels notpulling at the front because transfer is out of gear. I just don't know how to check for this .