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Major Vibration?!?!

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by z71roids, Mar 4, 2014.

  1. z71roids

    z71roids New Member

    Hey guys, I'm having some problems in my 04 Silverado z71 with 109k miles... Recently I changed out my transfer case because mine was grinding and worn bla bla whatever, but I got it fixed.. Now all of a sudden, my 4x4 is not working and there is a horrible vibration coming from up front anywhere from 15- 40 mph (fastest I went was 40 because I was afraid my truck would fall apart). I'm lost on this one, first time I've encountered this problem and it can't be good.. The way its going i'm about ready to take this thing to the junk yard and count my freaking loses because its one thing then another then another. Please help me out..
  2. Pikey

    Pikey Moderator Staff Member 3 Years ROTM Winner 1000 Posts

    I would check out the front drive shaft. Did one of the straps that hold the ujoints to the yoke crack? loosen? I had one crack. It took me a week to figure it out, then I saw a hair line crack in it. it allowed the ujoints to move in the yoke.
  3. z71roids

    z71roids New Member

    And that was making your truck go crazy with vibration?
  4. Pikey

    Pikey Moderator Staff Member 3 Years ROTM Winner 1000 Posts

    yes, the u-joint slopping around in the yoke, up and down, vibrated like crazy. It actually wallowed out the yoke on the rear pinion enough that I had to replace the yoke.
  5. buckmeister2

    buckmeister2 Member 1 Year 100 Posts

    maybe I am missing something, but he said his "4x4 is not working". I would assume that would mean not engaging, which would mean the front shaft would not be turning, right? I think we need more info on what the OP means by "not working".
  6. Pikey

    Pikey Moderator Staff Member 3 Years ROTM Winner 1000 Posts

    The front driveshaft on these are always turning. I read somewhere that it spins with about 35 ft/lbs of torque even in 2wd. Engaging the t-case in 4x4 results in power going to the front driveshaft and the front actuator engaging.
    Last edited: Mar 5, 2014
  7. z71roids

    z71roids New Member

    Yeah, the front drive shaft is always working, but in the means of not working I mean, I hit the 4x4 button, the transfer case engages (I can hear it engage) and then I get nothing.. only the rear wheels turn. I have no clue if this is what is making my truck vibrate but if so cool, two birds one stone

    - - - Updated - - -

    You say your strap had a hair line crack in it? so that means it could be there and me not knowing? Also can I buy new straps at a advanced auto and do you think it could be the actual u-joint?
  8. Pikey

    Pikey Moderator Staff Member 3 Years ROTM Winner 1000 Posts

    if you hear the t-case switch into 4x4 then chances are that you have a problem with the actuator on the front diff. You can pull it out, put it in 4x4 and see if the piston extends. I would venture to say that this is not causing your vibration unless you have something majorly wrong in the front diff. Again, I would check out the drive shafts.

    - - - Updated - - -

    It could be a u-joint. the best way to tell is to see if you have any play in them. I could move my driveshaft up and down in the rear pinion yoke 1/16 of an inch. With a vibration as bad as you are describing the issue should be pretty obvious. Crawl under there with a pry bar and see if the joints have any lateral play. Check at the pinion yokes for play. My strap cracked when I was tightening it down to push the ujoint cap into the yoke. I was in a hurry and did not clean up the yoke with sand paper. Even the rearend shop that replaced my rear pinion yoke did not notice the crack when they worked on it. I decided since I had a new yoke I was going to put new straps on, I pulled the old straps off and noticed the crack in the sun light. I found my straps at Napa auto parts.
  9. RayVoy

    RayVoy Well-Known Member 2 Years 1000 Posts

    The t-case should not be sending power to the front driveshaft in 2wd. It should be completely disconnected from the rear wheels and engine torque when the t-case is in 2wd.

    When the selector switch is moved to any of the 4wd positions, the shift motor engages the t-case to send power forward. When the selector is in 4HI, or 4LOW the power forward is equal to the power rearward. When the selector is in 4AUTO, the clutch pack is not fully engaged, there is some clutch slippage until wheel slippage is detected. In this position, a small percentage of the torque is sent forward, maybe 5%, but sufficient to turn the front driveshift.

    On the AWD trucks (like Cads and Denalis) the front drive shaft is turned by both the t-case (read the 4AWD above) and by one front wheel. In an open diff, one axle is always connected to the diveshaft.

    When the 4WD trucks are in 2WD, the open diff should flop to the passenger axle, which is not connected to the wheel, when this happens, the driveshaft will not turn because it is not being driven by the front wheel.

    In my opinion, 109k miles should not wear out a t-case, let alone two.

    To the OP, under what conditions are you using 4WD?
  10. buckmeister2

    buckmeister2 Member 1 Year 100 Posts

    Post deleted by author...
    Last edited: Mar 6, 2014

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