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Shudder on Take Off

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by rem7600, Jun 2, 2000.

  1. rem7600

    rem7600 1/2 ton status

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    Location:
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    I've read through some of the older posts regarding this but am not reading my exact problem...

    I'm getting a shudder on take-off. Took it to the tranny shop today and had them diagnose... They informed me that my left motor mount is loose causing a bump when the tranny is in drive. They also took the angles down.. They are as follows...

    6 - Down
    16 - Drive Line
    3 - Differential

    My understanding is that the 3 and 6 should be equal
    and thus cancel each other out... What's up with the 16
    degree pitch?

    What options do I have for taking care of this? How expensive might the fixes be? They looked at U-joints and said that they were in good shape but that the shudder will cause excessive wear which I already knew from searching older posts.

    Any help? In english please! :-)))) Thanx Guyz!

    [​IMG]
    <font color=purple>REM7600 - '89 Jimmy</font color=purple>
     
  2. HarryH3

    HarryH3 1 ton status Author

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    Location:
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    A worn out slip joint in the rear driveline will cause a bump when starting out from a standstill. It almost feels like you were lightly rearended. Replacing the slip joint will cure the problem.

    What happens is that as you apply power, the slip joint binds. Then the pinion shaft starts to move upwards, forcing the driveshaft length to change. The tension builds up in the slip joint until is releases with a bang.

    It won't really hurt anything, it's just annoying. If you lay just off to the side and look underneath as someone else slowly applies power, you can see the shaft jump if this is the problem.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <font color=blue>http://ThunderTruck.ColoradoK5.com</font color=blue>
     
  3. rem7600

    rem7600 1/2 ton status

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    Thanx Harry... The bump is actually from the
    loose motor mount. It's the shimmy or shudder
    that I'm hoping to solve next... Again, this
    is only from a standstill.

    [​IMG]
    <font color=purple>REM7600 - '89 Jimmy</font color=purple>
     
  4. Chris Demartini

    Chris Demartini 1/2 ton status

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    <font color=blue>This happened to me after i did my suspension lift, turned out to be loose rear u-bolts</font color=blue>
     
  5. CBLAZER81

    CBLAZER81 1/2 ton status

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    If you have a lift with rear blocks it could be axle wrap.I have the same problem and am narrowing it down to that.Personally I'm trying to save the$$$ for a shackle flip kit.

    <font color=red>Wanna'keep wheelin? Get involved!
    Check the "Land Use" section of this board.</font color=red>
     
  6. jarheadk5

    jarheadk5 1/2 ton status

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    Shudder on Take Off...sounds like something one of my pilots would write up against the aircraft!!

    I believe your 3 and 6 deg. angles should be within +/- 1 deg. of each other for minimum vibration. Shims under your rear springs can fix that.

    [​IMG] Semper Maintenance!
     
  7. rem7600

    rem7600 1/2 ton status

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    Thanx Marine... If that's all it is, no biggie...

    Question for all - What is the best way to find a 4X4 shop.
    I have only one shop that I trust fully and this may sound
    dumb but it's the local GMC/Pontiac dealer, Robideaux
    Motors. They have always been honest and up front and I
    appreciate that. Other garages around have been less
    than forthcoming and that really gets to me...

    Wish I had a garage so I could do the work but that'll be
    a few years out.

    All 4 now... Any insight will be appreciated.


    [​IMG]
    <font color=purple>REM7600 - '89 Jimmy</font color=purple>
     

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