engine vibration?

[MHPRUITT]

I wanted to post this for anybody that might run into this. I had a vibration in a car that I picked up. We went through everything, belts, pulleys, steering dampners, you name it. It finaly turned out to be the least likely candidate, the torque converter. Tested it by pulling the trans. and putting the bell housing back on with the old flywheel. Next step would have been to change the flywheel but I that's another story. In checking aroung the country I found this vibration thing is fairly common, well maybe just "not unheard of". I was amazed when we fired it up and the vibration was gone. Much time and money spent. Worth putting in your "did you try this" file.

Thanks for your previous input, Mark.

 

[tbird5866]

It sounds like you left out a step. You put the old flywheel back on and the vibration was gone. But the problem was the torque converter, right? How did you determine the vibration was the torque converter?

 

[MHPRUITT]

Hi Harley,

This is a little long but... the first step was to verify that it wasn't a miss fire of any sort. Next we changed motor mounts, trans mount and steering gear isolator bushings. Then at the sugestion of a trany guy that works on older stuff we made sure the engine and trans were squared up. While we were at it we made sure the frame was straight. I then removed each belt one at a time and started the car. Then I changed the harmonic balancer. No change. Finaly, I pulled the trans. primarily because the seals were gone but several folks had mentioned flywheel or torque converter as possibilities. The flex plate being the most probable. While the trany was out I obtained a new torque converter and a new flywheel. The old flywheel was a correct 390 flywheel. No external balancing and it matched the new one visualy. I bolted up the bell housing and starter without the torque converter and the vibration was gone.

As the trans can not be the problem because the vibration occurs in and out of gear it had to be inside the motor or ahead of the trans as I'd eliminated everything in front of the motor as well as underneath it or supporting it. The motor was not worth rebuilding so I may never know that it was not inside the motor 100%. I think that I found the problem to a certainty of 95%. One thing that helps confirm this in my mind is a guy at Hilltop Classics in California that said he had a similar problem with a Bird and only solved it when they went wholesale on the trans and flywheel. He didn't know what exact part cured it but it went away along with the old parts.

That's my story, and I'm sticking to it!

Thanks for the reply, Mark.