When I replaced 2 U joints, I did not make very good marks on the prop shaft before disassembly. Needless to say, the front half might not be correct. The U joints no longer all point in the same direction.

IF it has been put on 'wrong', what will the consequences be? All seems to be smooth at 60 mph. At 70 mph, my hood/bonnet shakes, but that could be due to out of balance tires?

The rear half of the prop shaft has been replace correctly, just not sure of the front half that goes through the center bearing.

Klaus
--
Why are Volvos so endearing? Its just a car.

I'm not quite sure where your confusion is--the rear half splined shaft gets inserted into the front half to set the alignment. All the u-joints should be on the same plane. The front most flange (the part that bolts to the tranny flange) and the rear most flange (part that bolts to the diff flange) should be aligned so they would form one "u-joint" if matched together (90 degrees opposed). Set that way there could be two "correct" positions as far as u-joint alignment. As for balance-on an original complete shaft assembly-only one of those positions would be correct. If you still don't understsand you can write me directly and I'll send you a drawing to illustrate what I'm trying to say. -- Dave

I took it to the Interstate just now and got it up to 70-75. No shaking. It must have been road surface before.

Now, the U joints. The front and rear are 45 degrees apart, not 90. So should I take the rear off, rotate it so that they line up, and bolt it back up? Jacking the rear wheels off the ground is no problem.

Klaus
--
Why are Volvos so endearing? Its just a car.

Klaus!
Sorry it took me so long to find this - I had to go through about 40 pages in the gallery
to find this pic because the search function will only allow selection of ONE variable
and sets the others to default values. This was NOT one of the last 20 I posted!
Anyway below is the way the driveshaft needs to be assembled to maintain constant
rotational velocity. Even if you don't feel vibrations it is rough on a lot of things if
it is not aligned properly.



Note that the yokes on each section of the shaft are aligned exactly.
Worst case is 90° apart, which doubles the rotational velocity variation.
--
George Downs, Bartlesville, Heart of the USA!

So I will have to drop the rear shaft, pull it out, turn it to match the front U joint, join the shaft components, rotate the shaft so that it fits back on the differential.

Sounds easy enough. No jack needed, tranny in N and brake on. Just a lot of laying on my back with tears in my ears.

Klaus
--
Why are Volvos so endearing? Its just a car.

My guess is it would be easier to put the tranny in P and jack up the rear and turn a wheel
to line it up right. You gotta drop the shaft at the rear anyway, might as well have
enough room to get under there comfortably.

I got tears in my ears
from lyin' on my back
in my bed while I cry
over yew......
--
George Downs, Bartlesville, Heart of the USA!

If the front yoke of the front section, GB end, is parallel to the ground the yoke on the sliding section should be identical. This will mean the rear yoke of the rear section is vertical. If you jack the rear axle up and undo the prop shaft, you can slide it out and repositio it. Should be even smoother then.
Pics in Haynes are the same as the Green Books.