Hey guys, I've found loads of good information over the years on this site just browsing. I finally had to signup seeking help for a specific problem. I'm working on a 1950 Chevrolet 4 door with a Powerglide and enclosed driveshaft. It has a driveline vibration I can't figure out. It starts around 45 mph and occurs during acceleration, deceleration, and cruising. If I shift into neutral the vibration stops and starts back up again when I shift back into gear. If I keep it in low and wind it up a bit there is no vibration. It only occurs around 45 mph and above regardless of engine speed. I have replaced the u-joint and the bushings and seal in the driveshaft tube with no improvement. Any ideas?
If everything else is good, IE rear end, tires, wheel bearings and the like that narrows it down to the transmission.LOL
Well that's what I was thinking. It doesn't change with engine speed so it isn't the engine, torque conveter/flexplate most likely. It also stops when shifted into neutral so that should eliminate rearend, tires, wheels bearings, etc. I've never had a transmission cause a vibration. What could be vibrating between the torque converter and output shaft?
Any place that there is a bushing or bearing.LOL I had a later power slip making me crazy once, being pig headed like I am I was not going to change it out for the one I had on the ground. Turned out to be the output shaft bushing.
This powerglide has the ball on the back. It doesn't have the bushing. I drove it again today and realize I was mistaken. The vibration does in fact stop in gear at while coasting if you feather the throttle to remove any load off the shaft. I think my next step is to pull the prop shaft again and have it checked for balance. Thanks for your suggestions guys. I'll let you know what I find out.
It is an enclosed shaft so there is no angle at the pinion. Had the shaft checked for balance and it is dead on. Still scratching my head.
Didn't check the rear spring bushings but all motor and trans mounts are new. I think we are gonna pull the trans and have the transmission guy go through it just to be sure.
When we installed new bushings in the shaft tube we used N.O.S. parts because the Okie bushings weren't currently available. When reinstalling the shaft after having it checked for balance the new bushing in the end of the tube slid out. there doesn't appear to be any play but you can pull it out by hand. Also when we installed the new ball gasket the ball became way too tight. You cant even move it by hand with 4 shims installed. Okie bushings are now in stock so I ordered one and another shim kit for the ball. I suspect one or both of those is our problem. Thanks for all your suggestions so far. I will keep you updated.
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