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Bad Vibrations

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by TWISTEDJACK, Oct 2, 2002.

  1. TWISTEDJACK

    TWISTEDJACK 1/2 ton status GMOTM Winner

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    With the auto in neutral from 1500-2500 the truck has a
    bad vibration. Feels just like a driveshaft vibration. Any
    idea what might cause this?? /forums/images/graemlins/1zhelp.gifMy first thought is the
    torque converter /forums/images/graemlins/confused.gif
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    I'd check easy stuff, such as all the converter bolts, flexplate to crank bolts, tranny mounts, engine mounts, etc.

    Maybe some more experienced tranny guys can comment, but I'd think a converter vibration would only be likely if the shell itself wasn't balanced. If the internals were vibrating, I'd think failure would come pretty quick.

    Guess you could always drop the pan and look for any abnormal amounts of metal, problem with that being there is almost always fine metal particles in the normal "sludge" in the pan, and it would be kind of hard to see if there was "abnormal amounts" in there. Chunks of metal though, obvious problem.
     
  3. imiceman44

    imiceman44 1 ton status

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    If you feel it in the drive shaft why do you think it's the t/c.
    It could be the drive shaft, U joints or both.
    Check the U joints first, then lift the truck and run it and see if you can feel it or see it vibrate, if it's a long drive shaft sometimes they bend length wise, as in arch.
    IceMan
     
  4. Can't be the driveshaft if the tranny is in neutral /forums/images/graemlins/blush.gif
     
  5. TWISTEDJACK

    TWISTEDJACK 1/2 ton status GMOTM Winner

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    I mean it FEELS like a driveshaft vibration. The vibration
    happens even when the truck is parked with the tranny in neutral.
     
  6. shane74

    shane74 1/2 ton status

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    Well, since it vibrate with the tranny in neutral, the first thing I would check is the flex plate, is it bent? Also, look at your fan , any cracks in the blades? Look at your harmonic balancer. Does it look like it's wobbling? Sounds like you have some bearings going bad somewhere. Mine did that with a loose fan blade and a crappy working clutch fan. BUT look everything over VERY carefully. What was one man's problem may not be yours.
     
  7. imiceman44

    imiceman44 1 ton status

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    Sorry, you didn't mention that it happened when you're not moving.
    Ok since I am saying stupid things, here's another, could it be the engine? a bad cylinder, a fouled spark plug, a loose braket...
    Did you check the engine mounts?
    The hydraulic pump?
    IceMan
     
  8. TWISTEDJACK

    TWISTEDJACK 1/2 ton status GMOTM Winner

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    Here is what I tried so far.
    Checked the Motor and tranny mounts....Good
    Unhooked the fan.......still vibrating
    Unhooked the torque convertor.....vibration stops.
    Still could be the flex plate. I am going to split them
    tomorrow night. I ran out of light to really get a good
    look at the flexplate. /forums/images/graemlins/confused.gif
     
  9. jjlaughner

    jjlaughner 3/4 ton status

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    I've got some Bad Vibrations also but its from 64mph and up on the highway. Smooth up till 63 after that it's martini time! I just replaced the drivers side motor mount, passengers side exhaust manifold, ujoints have several thousands of miles but where timken (?) I think. Rebuilt 700R4 about 24K miles ago. Rebuilt front 10bolt 2 years ago, rebuilt rear 10bolt about 1 year ago added an auburn limited slip. Factory springs with add-a-leaf, 10bolts, 3.08's (says shipping receipt and gas mileage) Its been getting worse and worse for about two months now but its my only vehicle at this point so no down time. Need more info hit my site Any ideas? I may start my own thread too... Looking for D44 and 14bolt, 4 in rancho softrides in Indiana cheapcheap.
     
  10. shane74

    shane74 1/2 ton status

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    Well, since yours is directly speed related, and it only vibrates above 63 mph, then I'd suggest you get your tires rotated and balanced. You can lose a weight on one and it can cause it to shimmy like a bee-yotch and cause the vibe to go through many different parts of the truck. Yours sounds like something other than a u-joint. I'd bet it's either bad tire balance, or maybe even an out of round tire /forums/images/graemlins/tongue.gif. /forums/images/graemlins/k5.gif
     

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