Taking out a driveline. Do you need to mark it and why?

[chalet2506]

Took the 2 pc driveline out of my F250 and had it rebuilt. New u-joints, new carrier bearing and balanced. Now I've got what feels like a driveline vibe between 55-70mph. I figure there's 2 possibilities.

1. The shop goofed it up, but I've used them before and they're reputable.

2. I didn't mark the driveline when I took it out to make sure it went the same way. I read now that you're supposed to put them back in the same position they came out, but I don't see why you need to?

Think I'll just trying rotating it 90 deg until either the vibe goes away or I make it a full turn. After that it'll go back to the shop.

 

[Cornfield creations]

If it's been balanced after rebuilding it shouldn't matter. Make sure you have the caps completely in the yokes, or the flanges. Make sure they're tight. It you have u-bolts for the caps, 15 inch lbs. Don't overtighten

 

[chalet2506]

No u-bolts, its flanged on both ends. I torqued them to "it won't go anymore" specs.

 

[diesel4me]

Some 2 peice shafts cant be put together "wrong" because they have a missing spline ,so it'll only slide together one way..others must be "clocked" correctly to get the phasing correct..usually the u-joint caps must be 90 degrees apart from each otherbut I recall some GM trucks being set 4 splines "off" too!...

Some trucks that use a center carrier bearing had a shim uder it,if that gets left off it'll screw up things too--some GM trucks back in the 70's needed a 1/2" thick spacer added under the bearing to eliminate a driveline shudder when it shifted into second gear...