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Heavy vibration and rattle after 4" lift...need help

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by chev4life, Aug 15, 2002.

  1. chev4life

    chev4life 1/2 ton status

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    Heavy vibration and rattle after 4\" lift...need help

    I recently lifted my '87 K5 4" using Superlift springs all around and all the new goodies to make it work. It rides great, tows better and I am way pumped....but there is one problem....when I let off the gas at any speed over 15-20 mph I get a rattling/vibration type thing happening in the entire truck. It sounds like it is metal to metal and I can deff feel it under my feet. Has any one else experienced this?....or know what is going on. I still have stock exhaust to the cat....and already checked the new exhaust after with no problems found. Thanks. /forums/images/icons/confused.gif
     
  2. Sandman

    Sandman 3/4 ton status Author

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    Re: Heavy vibration and rattle after 4\" lift...need help

    I would guess u-joints would be the first thing to check. They can be OK with out a lift but the extra angle might have done an older one in when it was lifted up.
     
  3. Swanson52

    Swanson52 1/2 ton status

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    Re: Heavy vibration and rattle after 4\" lift...need help

    Did you lower the tcase at all? Check your rear driveline angle...most 4" kits don't create a problem, but on occasion the lift makes the rear driveline angle too severe, and the slip yoke will hit the fixed yoke on the driveshaft. Chock the wheels, throw it in neutral and crawl underneath and rotate the shaft. You'll be able to see if the driveshaft is hanging up on itself.
     
  4. chev4life

    chev4life 1/2 ton status

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    Re: Heavy vibration and rattle after 4\" lift...need help

    I will check all the joints...if needed, how difficult is it to replace the u-joints and lower the t-case. I thought about doing the t-case but never got that far.
     
  5. Scott73

    Scott73 Registered Member

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    Re: Heavy vibration and rattle after 4\" lift...need help

    lowering the transfer case is pretty simple. Support the transmission and transfer case, remove the 4 bolts from the crossmember and relocate the spacers that are under the crossmember to between the crossmember and the frame. Takes 10 to 20 minutes. I just did my '87 this weekend.
     
  6. Swanson52

    Swanson52 1/2 ton status

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    Re: Heavy vibration and rattle after 4\" lift...need help

    Yup, that's how I have done it.
     
  7. Blue85

    Blue85 Troll Premium Member

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    Re: Heavy vibration and rattle after 4\" lift...need help

    </font><blockquote><font class="small">In reply to:</font><hr />
    Chock the wheels, throw it in neutral and crawl underneath and rotate the shaft.

    [/ QUOTE ]

    Of course, you have to lift the rear wheels off the ground to check the rear driveshaft, or at minimum one of them.
     
  8. Oddball

    Oddball Registered Member

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    Re: Heavy vibration and rattle after 4\" lift...need help

    Drop the T-case and check / lubricate the joints...
    If you got grinding noise i would have them changed.

    I lifted my 77 4 "-- and didnt drop the t-case at first..
    so front shaft broke.. then i dropped the t-case.. no moore vib's.. but then rear shaft joint said godbye on the highway going 75. that wasnt fun

    Truck is ok now.
     

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