Out of phase front shaft
 

Just had my front prop shaft rebuilt and installed it. Only problem now is some vibration from very slow speeds up to highway cruising speeds.. A constant vibration. Tires are balanced and brand new. Took it to a local drivetrain shop and they can't find anything wrong with the shaft but say it looks like it is out of phase. What is the correct setting for it to be in phase?? A photo or how many splines one way or another?

not sure what they mean 'out of phase' but did they balance it after the rebuild?

Nope, individual that rebuilt it had no way to balance it. I got it back and put it back on the truck. Now it is at the local shop that does this type of work. He called me and said he found nothing with it except that it may be out of phase.

By out of phase they could mean either you re-installed it in a different orientation or that they did not keep track of the orientation of the 2 halves and they screwed up.

IIRC the DII front slip yoke is keyed and will only go in one way.

it probably just needs to be balanced

i think his brain is out of phase. and it needs to be re-balanced.

That shaft HAS TO BE BALANCED ASAP!!!!

So, I'm curious about this too. I just rebuilt mine and I was very careful to line everything back up the way it came out. It all feels right at any speeds below 70, but I've noticed a very slight vibration beginning between 70 and 80 mph. It might not even be coming from the front drive shaft, but how noticeable would it be if it needs re-balanced?

Just stop speeding ;)