After renovating both the engine and the automat, I have vibrations. Not sure if they come from the engine or the transmission. Can the flexplate versus converter be wrong? or the flexplate against the crankshaft?

I`ve been wrenching Chevys since the sixties, so I´m not without experience. I guess I have the take the whole package out.

Any other suggestions?

Hoping for some smart solutions.

 Bo Authèn   Sweden.


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Most likely the propellershaft. Bring the shaft to Sveabil in Bromma. They will balance and fix the CV-joints. Its not cheap but a lot cheaper than starting anywhere else. 

No, that`s not the problem, it`s been rebuilt already. I think I will take the transmission down and look for a broken flexplate or converter.

This happened to me after installing a replacement engine in a '64 Cadillac. I had a vibration once I had everything together and the car running. So I pulled the car up on ramps and took off the dust cover on the trans bell housing while the car was running. I could see clear as day where the vibration was coming from. Turned out the flex plate was bent. I swapped flex plates with the one from the bad engine and that did the trick. 


Was your car on the road and driving with no  drivetrain vibration  before  the vibration showed up after the rebuild ?

If so that would eliminate the propeller shaft ( driveshaft ) from being any  issue now 

If the car is on the road for the first time —after this engine and trans rebuild the propeller shaft could be the vibration issue

Propeller shaft vibration is the most common drivetrain vibration issue on this site which comes up very often. ( much more on that  later if it is a possibility  ) 

Do check the flex plate -inside the inspection plate for out of round with )engine running as suggested here

Are all your engine and trans mounts new and fresh ( trans side  mounts adjusted correctly for a snug fit ) 

Did you change the  engines harmonic balancer for any reason ? 

Any vibration issue can be difficult to trouble shoot - I do feel your pain  with  this kind of issue 

Check out the things suggested on this thread and let us know if any help you out 


Thank you for the answers, I will check all of the solutions and hopefully solve the problem.

Thank you, a great forum.


Pls do let us know what it was  when you solve the vibration problem so many others can benefit from your quest 




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