Hello all.
This is my first ever post on anything ,and I am happy that it is on the Brick board as it has been tremendously informative on so many matters,and made the self maintenance of my 98 A.W.D.V70 so much more succesful. I hope this is my chance to give something back.
Ever since I took the car over three years ago there had been a growing "whine" from what I took to be the centre bearing in the propeller shaft to the rear wheels. Somtimes it could become a brief but startling "chatter"(usually at low speed)if conditions just caught it right.
Jacking all four wheels clear and static running didn't clearly show what was going on, because for some reason the so called freewheel unit produced noise far beyond what was being complained of,and quite different in character.
As time went by,I got used to the "whining" noise,and tried to regard it as something trivial.
I aquired my own Four poster ramp and this enabled me to really inspect what was going on underneath the car at all sorts of speeds up to eighty m.p.h.(wife in the pilot's seat; me on the ground with the lamp and stethoscope) but the noise of the freewheel unit again predominated.
As I had begun to experience mild bumping by the propeller shaft,(usually on tight left hand turns)I could no longer simply class the symptoms as trivial with any sense of honesty.Furthermore,tight manoeuvring on loose surfaces produced a worrying degree of tyre scrub noise. I get this same effect on the same surfaces with my Honda quad bike, (ATV)this is 4wd with a diff. for the front axle, but a solid "live" rear axle. It's intended for use on mud and grass, and has wonderful grip, but on tarmac the lack of rear or centre diffs. makes the steering heavy and it requires some effort at speed.
However,when parking,if you put the steering on full lock it produces a mild but useful handbrake effect,and she will not roll easily.
I considered that the V70 was going the same way as the Honda atv had always been.
Experimentally I did three things--

First,I decided that although the rubber mounting for the centre bearing was intact- it was now too soft.So,using a piece of resiliant foam rubber(neoprene)and polyurethane sealant/adhesive I bonded an insert about 1.5"x1" into the centre bearing rubber mount at "6 oclock". This produced what I judged to be just the right amount of firmness.

two.--

I made a grease needle from some capillary tubing and a grease nipple. With this I injected(under the slacked off gaiter clips)two wallnut sized quantities of C.V.Lube into each of the two C.V.joints on the prop. shaft.
The centre universal joint has no way in, so nothing could be done there,but it seemed OK without any play or rusty leaks. The C.V.joints had each a trace of play, probably more than when new,but they seemed quite serviceable.
Three.--
With a compressed air paraffin gun I blasted fluid lanolin into the center bearing after leaving a day for the polyurethane to set first. I also blasted the freewheel unit. I had put a stripe of paint on it to show me what part moved relative to the other, so I knew where to aim.
The road test showed that everything was better. We still had a slight "whine" but not as intrusive. After two thousand miles I have never had the propshaft "bump" on turns;I have not had the nasty "chatter"; AND--AND I seemed to get about two mpg more, but this dropped back when I fitted new tyres.(larger unworn tread dia.?)

I believe that the cyclic velocity of the centre universal joint coupled with the play in the C.V.joints undamped by old less fluid lubricant produces "chatter"and "whine". Also the more responsive, lubricated nature of the propshaft allows the front and rear diffs. through the viscous coupling to "unwind" as the designer intented they should. I can't say that I can explain this point perfectly in this posting. All I can do is offer the information in good faith.
It improved my car in a sustained way at little cost when I thought an expensive solution was the only way ahead.
We won't count the cost of the ramp.
Buy the 1/2"sq. socket set, KLAUS,and more.A man with your knowledge and interest is easily worth it.
Howard, Isle of Skye.
"Nil desperandum."