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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."
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What a great post! And a good insight as to what is wrong with our AWD cars. Most have the shudder at low speed and cannot find anything wrong. I suspected CV joints, there are just too many of them.
You have a 4 poster lift??? Boy, am I jealous. When I retire, I hope to buy a small building and rent it out(cheaply) to those Volvo nuts who want to come and tinker with their cars. A lift would really help things. Along with a good coffee machine, of course :)
Sears is on my place to visit for more tools. I just got my wife's approval to beat the dealer labor rates :) But everything is on hold this week, some of my windows are being replaced and they needed garage space to store the windows. A good time to order struts, etc.
Klaus
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The 164 has a new home, all I am left with are a 95 854T and a 98 V70R :)
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Thanks Klaus.
The use of C.V. joints on a propshaft is a fairly modern practice, and may not be widely understood by precedent.
It could well be that the higher speed,(engine r.p.m. in top gear)causes the lube. to "cake up" centrifugally when it ages, and with little angular displacement (unlike front axle C.V. joints) it stay were it was flung,inside the gaiter (or boot). I notice that propshaft gaiters are not convoluted as axle ones are, this may be an acknowledgement of the higher speed by the designer.
The mixture of C.V.joints with a none C.V. joint is intersting and probably quite acceptable if the angular displacement of the non C.V.joint (or universal joint if you like) is absent or small. However, with age, wear, stiffness, slackness, friction, lubrication, torsional vibration, road surface, and the moon and stars being right;it may start a "chatter" in the slightly worn C.V. joints.
"Bumping", is I believe, caused by the relationship between the weak positional register of the centre bearing mount, and the dynamic stiffness of the under lubricated C.V. joints when under the loads imposed by the difference in the speeds of the front and rear axles, on tight turns. Just observe the differing radii of the wheel tracks of a car on snow when making a tight turn.
I believe that the slight stiffness in the C.V. joints will translate into shaft misalignment that cannot be resisted or resolved by the floppy centre bearing mount, and this results in vibration/"bumping".
The viscous coupling cannot help if these forces don't reach it!!
Best regards, Howard.
Self preservation is the last law of averages.
(Stan Laurel)
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Howard,
You have come up with a good solution to an expensive problem for us early AWD owners. I have posted your fix on V70R.com and the responses are positive. Only one has stated that the fix will only put off the inevitable replacement of the shaft, which is quite expensive. An other has done what you have done and it is still working after quite a few miles.
You are correct with your assumptions about the CV grease collecting in all of the wrong places at speed, so that when you go slowly the shaft shudders. The shudders go away after a few minutes of sitting still, because of the grease moving to other parts of the shaft.
I am NOT going to replace the drive shaft in my AWD car, it is too expensive and will only show up again after 100K miles or less. I will squirt a little CV lube into the joints to see if the slow speed shudder goes away, I like cheap fixes!!! :)
Thank you,
Klaus
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The 164 has a new home, all I am left with are a 95 854T and a 98 V70R :)
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