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help b4 somethin' snaps!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bdan, Nov 16, 2002.

  1. bdan

    bdan Registered Member

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    help b4 somethin\' snaps!

    My '76 Jimmy suddenly has started vibrating badly when I give it gas(moving only). Seems to be lacking power too. It feels a lot like the final miles b-4 a u-joint on the front driveshaft exploded(but worse). I've been under the thing every day w/ a prybar looking for loose bolts/mounts- none found- everything(incl. u-joints) looks tight.
    It's been whirring when cold since I bought it (6 mo.)- shifting into drive first time in AM- noise coming from converter (I.D.'d w/ bellhousing cover off)Noise goes away quickly when driving.
    The thing shifts fine but shudder getting worse. Is it possible converter is only problem? Any quick checks of the diffs?(d44+ 12b)- I thought of loose flywheel to crank bolts but doesn't look loose(prybar).The flywhhel does wobble just a little when idling.
    This truck is so basic- I love it but I can't figure out what to fix! /forums/images/graemlins/1zhelp.gif The fluid is there and red-don't know when last changed
    btw its a 400ci w/th350 and np203- "65k mi" 4"BDS lift 4 months ago.
    Thanks for any input.
     
  2. BigBurban350

    BigBurban350 1/2 ton status

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    Re: help b4 somethin\' snaps!

    If your drive shaft angles are bad, that would cause a vibration under load. Other then that, I would just wait till something breaks. I am prepared for stuff like that on my truck, like a driveshaft loop in the rear(broke 3 driveshafts as of now). Good luck. /forums/images/graemlins/burb.gif
     
  3. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: help b4 somethin\' snaps!

    If it's still fulltime then pull the front drive shaft and check the CV. I have one go bad and I checked that thing no less then five times with it in the truck and could not see a problem with it in the truck. It finnaly made a noise I recognized as a U-Joint failing. Pulled the front shaft and sure enough there was a bad u-joint in it.
    Another thing is did you correct your front pinion angle if this thing is still full time? The pinion has to be in line with the drive shaft. it usualy requires a 2.5 deger shim to get the angle correct.
     
  4. 74Chev

    74Chev 1/2 ton status

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    Re: help b4 somethin\' snaps!

    I am guessing that the bolt circle on the flex plate if probably clmpletely broken all the way around. I have seen this problem before and the symptoms are exactly what you describe. The only way to know for sure is to pull the tranny and check it out. You probably have checked the flex plate bolts but make sure they are all in and tight.
     

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