I have a 1955 Oldsmobile, Super 88. It has the 324 OHV V8 which has about 3000 miles on a complete rebuild (about1995). I have been working on the car since I was a kid in the 80s. I had the transmission rebuilt then. It runs and shifts fine. I have been chasing vibrations and I am down to one. I get a vibration from underneath the car from 33 up to 35 mph. It will vibrate at the same speed in second, third and forth so it is NOT dependent on engine speed. I would think this would rule out harmonic balancer, fluid coupling (torque converter), engine balancing, etc. The car will also do it without the drive shaft in so this leads me to believe it is in the transmission. Thus ruling out u-joints, tires, drums etc. I have wiggled the shaft coming out of the transmission and it seems solid. I think there is a bushing and maybe a bearing in there. Is this where I should start looking? What are the part #s and where could I locate them? In Canada? What else should I be looking at? Everybody in my small city who worked on these are no longer available due to old age or death. Please help!

 

Do you have a shop manual for the car? You could check transmission section for clues. I have one for my 49 and it seems to have more info on the hydramatic than anything else. How did you get the car to 33 miles per hour without the drive shaft?

 

You can source older transmission parts from Fatsco.

http://www.fatsco.com/

 

Thanks for the info. I do have the maintenance manual for it. Unfortunately, I am not experienced enough with transmissions for it to help me. I ran the car without the drive shaft in (sitting still on my driveway) and watched the speedometer. When it got to 33 mph, the same vibration. I didn't actually have the car rolling down a hill. This shouldn't make a difference???? Thanks for the replies. Any other info would always help.

 

Just a shot in the dark , You might check for a seperated or broken motor mount. Noise can telegraph. Also check for a loose bolt on the transmission, mount may be fine but bolt will rattle at a certin RPM. ...Tedd