Vibration right off idle

Transmission and Drivetrain Tech

  1. plumkrazee70

    plumkrazee70 Well-Known Member

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    I have the car on ramps and it's level, so good there. Sorry, but are you saying keep both the pinion and the trans at 2-2.5*? And is that in both directions?
     
  2. 512Stroker

    512Stroker We are all here because we are not all there.

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    Set the trans so it is pointing up +2.5 degrees
    Set the rearend pinion so it is down -2.5 degrees
    Negitive or positive 2 to 2.5 is just a range to shot for.
     
  3. plumkrazee70

    plumkrazee70 Well-Known Member

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    I don't think I can get my trans that high. I'll try shimming tonight.
     
  4. 512Stroker

    512Stroker We are all here because we are not all there.

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    Try real hard or live with the vibration
     
  5. George Jets

    George Jets 1967 Dart 2 Door FABO Gold Member

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    Look at the trans on the right 904
    Then look at the overdrive trans on the left at how much longer it is than stock.

    Screenshot_20210410-203807_Chrome.jpg

    Being your overdrive trans is longer, you end up with a shorter driveshaft and in the process it steepens your driveline angles.

    What is the tailshaft angle right now, car sitting level, and no shims at the tail shaft mount? 2° Negative ????

    Now measure the rear pinion angle, what is that, 2° Positive ???

    This is the senario you want with Negative degrees at the tail shaft and Positive degrees at the pinion shaft.

    Raising and shimming the trans tail higher is going the wrong way, giving you too sharp of a driveshaft to tailshaft angle.

    _________

    Let's see what your angle degree measurements are to start with.
     
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    • 512Stroker

      512Stroker We are all here because we are not all there.

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    • George Jets

      George Jets 1967 Dart 2 Door FABO Gold Member

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      Yeah that's a good article. ^^^^^
       
    • George Jets

      George Jets 1967 Dart 2 Door FABO Gold Member

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      Good:
      Screenshot_20210410-234509_Gallery.jpg

      Bad:
      Screenshot_20210410-234615_Gallery.jpg
       
    • CudaFactHackJob

      CudaFactHackJob FABO Gold Member FABO Gold Member

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      Ever notice how the carb is always level, but the drivetrain is tilted down in the back? And the manifold is angled about 3 degrees? You tilt the motor/trans down in the back about 3 degrees, and the pinion up 3 degrees. That article was written by a person who really doesn't understand driveshaft angles. Read his last post about Sunbeam Tigers. Driveshafts don't know the angles of the two units they are connecting, so up, down, left, right; don't matter to a driveshaft; only the overall angle; measured from any perspective.
       
    • George Jets

      George Jets 1967 Dart 2 Door FABO Gold Member

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      3° down at the engine/trany
      3°up at the pinion
       
    • plumkrazee70

      plumkrazee70 Well-Known Member

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      Sorry, guys. I missed these updates. All I have read is that you want what @George Jets is saying. (trans (-) and pinion (+) the same measurement to offset each other.

      So in my case: trans is -2.5* so my pinion needs to be at +2.5. Currently my pinion is -3.9*

      So if I roll the pinion up +6.5* that will give me a pinion angle of + 2.6 (-3.9+6.5).

      If the pinion rolls up 2* under power. Then I can subtract 2* from my shim. So I need to roll the pinion up 4.5*.

      Totalling .6* at rest and 2.6 under power.
       
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      • oldkimmer

        oldkimmer FABO Gold Member FABO Gold Member

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        He posted them already. U absolutely do not want the pinion higher than the trans. The way u describe it he would have 4* positive. Kim
         
      • oldkimmer

        oldkimmer FABO Gold Member FABO Gold Member

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        No no no no no
         
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