Eternal Vibration Worries - Aod

mhjo · Jul 23, 2013

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)

66Coupe289POWER · Jul 23, 2013

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.

mhjo · Jul 23, 2013

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

woodsnake · Jul 23, 2013

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

66Coupe289POWER · Jul 23, 2013

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

rbohm · Jul 23, 2013

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.

Rusty67 · Jul 24, 2013

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 ?

mhjo · Jul 25, 2013

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

Rusty67 · Jul 28, 2013

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.

Eternal Vibration Worries - Aod

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