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Hydra-matic transmission

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New User

Jun 11, 2010, 10:50 PM

Post #1 of 4 (3677 views)
Hydra-matic transmission Sign In

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!

Veteran / Moderator
Sidom profile image

Jun 12, 2010, 9:07 PM

Post #2 of 4 (3665 views)
Re: Hydra-matic transmission Sign In

You know I don't have a real good answer for you.

Not being able to feel the vibration makes it tough. I would want to be triple sure this is in fact the same vibration you are feeling with the driveline out of the car as the one its making with the driveline in the car.

I guess one thing you could try would be to take the trans mount loose & support it with a piece of wood & floor jack and see if that makes any kind of difference on the vibration....


New User

Jul 7, 2010, 10:36 AM

Post #3 of 4 (3621 views)
Re: Hydra-matic transmission Sign In

check your wheel bearings and the steering links,suspention components,tires for tread walk,alignment,,if those r good try turning 180 the relation of the drive line yoke to each yoke,one at a time,so flip the yoke at rear end first n drive it,if worse flip it back n try the yoke relationship at tranny output shaft,I really dont think it would b an internal prob,,,hope this helps :)

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jul 8, 2010, 4:59 AM

Post #4 of 4 (3617 views)
Re: Hydra-matic transmission Sign In

I think this driveshaft may use "constant velocity" u-joints such the joints can be ok but the centering ball and spring can go bad. It would be load sensitive.

Parts? Once a member of The Oldsmobile Club of America and you can just Google it for folks who would have parts if you can't find them elsewhere. There are driveshaft specialty places that might be able to alter it to something more dependable IF and only IF that's the trouble and parts are too difficult,


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