I rebuilt my first 727 in 1985. I did a reverse valve body mod, that 383 would smoke some rubber and it was a pretty quick car. That lasted a year and it locked up on me cruising at 40 mph. I thought the 4:10 diff locked up until I looked under the car and saw bellhousing pieces on the ground...
I just removed the wheels and drums, vibration still there. Narrowed down to driveshaft or transmission. The drum I beat off apparently was not the problem even though it is missing a chunk.
I just confirmed the vibration is still there in Neutral at 45mph, rpms dropped to 1000. I guess I'm going to take the new driveshaft back to Gregory's and have them check it. But, I suppose I could take the new tires and wheels off the rear , put it on jack stands and see if the vibration is...
Might as well add my story. My 833od has a vibration at 40ish mph when shifting to 3rd, gets worse in 4th. 1-2,3rd, 4th under 40mph no issues just a whine in 4th only.
Any speed past 40 in 3rd/4th the vibration is there. And its severe.
Can't take the car to 40 in 2nd due to my rpms are maxed...
I just installed P4120864 and 63. Supposed to be for a 2800lb car. Now my car is jacked up in the rear. All fasteners were tightened with the axle up. It’s pretty bouncy right now. I’m going to take the load off the front suspension and raise the front. Dang it.
So been driving for 5 days with the valvoline synchro. The shifting is perfect. Not one crunch or hard to get into any gear. The downside is the trans is noisier and feels looser, probably because my 833 needs a rebuild. But it just shifts perfect after changing to synchromesh. I might drain...