Ok, I will try my best to explain my issue and what I have done to resolve it, this may get long (I will put a TLDR below)

I have a 98 Olds Bravada that I have owned for 3ish years. Ever since I have had it, it has had a vibration at highway speeds. Nothing I have done has changed the vibrations, for better or worse. I will list all of my repairs below, not all are directly related to fixing the vibration.

Tires re balanced
Transfer case fluid change - put the correct GM fluid in it, not sure how long it had the incorrect stuff
Lower ball joints - passenger and driver
Swapped wheels and tires with friend (did not change)
New brakes all 4 corners - rotors and pads
New U joints (slightly bent front ears so front u joint was tight - this has since been replaced as you will see below)
New tires
New drivers upper control arm - bushings gone
Front drive shaft removal (no change)
Passenger side wheel bearing
Replaced drive shaft with one from junk yard - installed new u joints

I tried to list these in the order they were done to the best of my memory. The most recent was the driveshaft. As seen above, I slightly tweaked the original one and that prematurely killed the front u joint. This was replaced this morning with brand new u joints and still no change.

Now to describe the vibration - its the entire vehicle, but not violent. Just enough to vibrate the mirrors and rattle something in the dash . This does not matter how fast the engine is spinning. I have tried manually changing gears while this is happening and nothing changes. I also put the truck in N and turned the engine off, no change. I had a buddy ride with me, he sat in the front seat and moved to the back and said he noticed it more in the front of the vehicle than the back.

I am running out of ideas. The ONLY thing that is even on my radar is the transfer case. Now the reason I say this, is my in-laws have a same year Bravada which I compared to mine. I know the transfer case should have some rotational "slop" however mine has 2 times the slop their's has. This is the front shaft I am talking about. Hopefully that makes sense. I cannot really measure this, but with them side by side, it is noticeable. There is not any difference in up/down movement between the 2.

I am about to the point to take it to a shop, however I have a feeling they will just throw parts at it, which I can do for cheaper!

TLDR - Bravada vibration ever since I have owned the vehicle, threw all kinds of parts at it, and no change... possible transfer case?

Thanks Guys.

 

I suppose its possible yes. Get a junkyard one instead of taking it to a shop. Shouldnt take too long to swap them out and see what happens. Better than paying a shop to do it for you for sure

 

i have a '98 bravada, and have had problems with vibrations since iv'e owned it. the transfer case knocks like a piston rod, but it hasn't broke yet, although the 4-wd shift motor swelled out like frozen pop can and no more 4-wd now. i have to say it worked like a charm up until that point. another thing is i understand the '98 is a one year only deal, so finding a transfer case is not easy. im going to the regular blazer, at least they are plentiful. the only difference in the bravada and blazer is cosmetic anyway.