Driveline vibration

Warren said

Hello,
On my 1974 Hang 10 I have been restoring I finally got it to a condition to drive on the highway. I has a cyclic vibration which is the worst at 45 MPH (bucket seat starts to shake). Putting it on rear jackstands, removing the rear tires, bolting on the brake drums, and then running up and down the speed range no improvement. Swapped driveshaft rotation 180 degrees no improvement. Removed driveshaft and had checked out for balance by a shop and it and U-joints are ok. Started investigating the automatic transmission rear bushing/bearing (as discussed elsewhere on forum) and maybe this is where the problem is. With the driveshaft still removed, I can move the rear output shaft at least 1/32" radially. So my question is, how much play should I have and maybe the rear ball bearing is the problem?

Thanks for your thoughts.
Warren

Click to expand...

1. be more specific on the issues, exactly when does it start, does it get worse or a little better faster, or does it go away at 55/60 and maybe return at 80 or not at all...
Does it do it at those speeds and if you pop it into neutral does it stay constant or get somewhat better....

2. the shop checked it for balance how? did they look at it? did they put it in a lathe? did they actually balance it? do they even have a balancing machine (you would be surprised at how many supposed driveline shops have none)

3. the vibration starts at 45 mph and you have what rear gear ratio ? did you recently go from 2.76 to 4.88 ?

4. with the shaft removed and you moving the out put shaft is a waste of time since the slip yoke is the ground hub surface in which supports the tail shaft in the housing on its bushing....

answer 1 thru 3