'61 Driveshaft Yoke Rotational Alignment Problem.

[ThumperNZ]

I have a TH350 going behind a 348 3X2BC engine which is a long output shaft type which is 3" longer than the prreviously fitted later alloy PowerGlide.
So now I need to shorten the driveshaft, so today I removed it but I noticed something strange.
Normally the driveshaft universal joint yokes are inline, that is both ends at the same angle. I realize that the universal joint in front of the mid bearing is on a spline, but moving from spline to spline still wont align it.
I noticed the yoke has a missing spline, so thought that must align it, but the splines on the male part of the shaft have no corresponding part, so the yoke will locate on each spline.
The car had previously been fitted with a late PowerGlide so wondered if the driveshaft had already been shortened and welded rotationally incorrect.
Can someone check and prove the rotational alignment of the yoke and the center to center distance of the first driveshaft section please?

 

[62impala409]

Your front shaft may be correct. The 61 shop manual shows the proper phasing of the U joints to avoid vibration issues. The joints are phased 90 degrees from each other. The manual has pictures. I found this old thread with more info. http://www.348-409.com/forum/threads/u-joint-phasing.7069/#post-62299

 

[Carl 1962]

I recently swapped out my original aluminium short PG for a TH350 in my 62 with 327. I recall that the yokes of front shaft needs to be 90 degrees out of synch. The center yoke is bolted to the front shaft with a bolt that has a special washer with the spline pattern on it that aligns with the missing spline. You can see the washer in this photo.

The best way to measure the length of the front shaft you need with the new transmission fitted, is to insert the transmission yoke fully into the transmission then measure the distance from the centre of the universal joint hole in the front yoke to the first bolt hole of the centre support bearing. This means that the center of the front yoke and the first bolt of the center support bearing will retain the correct length relationship. I did it this way and I had to shorten my front shaft my 40mm. It was spot on.