Eternal Vibration Worries - Aod

Discussion in 'Classic Mustang Specific Tech' started by mhjo, Jul 23, 2013.


  1. mhjo

    mhjo Founding Member

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    I swapped a fully functional C4 to AOD 2 years ago.

    After the AOD was installed I noticed vibration in 3d . The vibration also occured in P/N when revved up to around 2500 rpm

    We canged converter, but it only got worse. A secondary vibration was introduced when AOD shifted from 2-3d.

    We swapped the AOD to a another AOD. Vibration only got worse. Now there is constant vibration i 40 mph in 3d and 60 mph in 4th.

    There was no vibration when the C4 was on.

    What are we doing wrong??






    (Oh, yes, The flexplate is the right OZ - we have checked several times)
    #1
  2. 66Coupe289POWER

    66Coupe289POWER Member

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    Do you have a 50oz or 28oz balance flexplate? The 289 should be 28oz so if you have a 50oz flexplate that would cause a vibration.
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  3. mhjo

    mhjo Founding Member

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    28 OZ. This has been checked and double checked. Last year we even put in a new one in order to be 100% sure...
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  4. woodsnake

    woodsnake Active Member

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    Drive shaft got rotated 180 degree's on the install maybe?
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  5. 66Coupe289POWER

    66Coupe289POWER Member

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    Maybe the harmonic balancer has spun on its hub? They are held together with rubber.
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  6. rbohm

    rbohm Founding Member

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    did you remember to reinstall the transmission vibration dampner? most automatics have one to prevent the very vibrations you are complaining about. it can be a weight mounted on an arm that bolts to the trans mount, or it can be an output yoke that has a dampner built in, or both. also make sure your drive shaft angles are correct, they need to add up to 180 degrees for the street. if the trans is 3 degrees down, the rear end should be 3 degrees up as an example.
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  7. Rusty67

    Rusty67 Well-Known Member

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    Which cross member did you use ? Which mount did you use ? Is it a poly or rubber trans mount ?

    What drive shaft do you have ?
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  8. mhjo

    mhjo Founding Member

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    woodsnake Active Member
    Drive shaft got rotated 180 degree's on the install maybe?

    = We are not looking at driveshaft right now as the vibration also can be felt while car I standing still.
    ·
    66Coupe289POWER Member
    Maybe the harmonic balancer has spun on its hub? They are held together with rubber.

    = We have already tried to change the balancer.

    rbohm Founding Member
    did you remember to reinstall the transmission vibration dampner? most automatics have one to prevent the very vibrations you are complaining about. it can be a weight mounted on an arm that bolts to the trans mount, or it can be an output yoke that has a dampner built in, or both. also make sure your drive shaft angles are correct, they need to add up to 180 degrees for the street. if the trans is 3 degrees down, the rear end should be 3 degrees up as an example.

    = I don’t know as I didn’t participate in the job

    Which cross member did you use ? Which mount did you use ? Is it a poly or rubber trans mount ?

    = I don’t know as I didn’t participate in the job

    What drive shaft do you have ?

    = Standard I suppose
    #8
  9. Rusty67

    Rusty67 Well-Known Member

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    I hate to be the one to tell you this but answering I don't know doesn't help. Try to find out and then post back. If you absolutely can't find out then let us know and we can try to help from there.
    #9

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