The Stovebolt Site Forums The Shop Area Engine Shop 2-piece driveline synchronization, or phasing.

in another post I had running someone suggested maybe asking in a new post about this subject. my drive shaft 2nd piece doesnt appear to be sync-ed with the front shaft. anyone know how to tell when it is correct? i have shaking in 4th gear.I have has the u bolts removed on the rear shaft, and I do not know how to put it back on the correct way

From THIS PAGE..
Most driveshafts are built with the yokes at each end of the tube aligned in the same position. If the transmisson yoke ear faces the side and the rear end yoke ear faces up, then the driveshaft could be phased wrong. Multi Piece driveshafts usually have all yokes aligned for best operation.

Another link w/pictures

another picture

Here's the technical answer, or where to find it:
http://www.stovebolt.com/techtips/driveline/setup/index.html

If the angle is very small it is phased one way, if larger than it's the other way. I won't try to explain how and why, the answer is in the manuals liked above and explains it better that I can..

Grigg

It's really pretty simple- - - - -just remove the rear shaft by unbolting it from the rear end, slide the slip yoke apart and reassemble it with the yokes aligned, or 90 degrees apart. Don't assemble the shaft in such a way that the crosses are misaligned by one or more teeth. The vibration comes from the driveshaft tube trying to twist as it turns, instead of the yokes flexing as the shaft rotates. Some of the smaller shafts have a keyed spline so they can't be assenbled wrong, but the larger ones have to be indexed properly as they're assembled.
Jerry