I've been chasing this vibration since last Fall.

Here is what has been done:
- Driveline rebuilt and balance twice, two sets of u-joints
- New center bearing & rubber support
- New Transmission mount
- Rebuilt Torque Converter (twice)
- New Brake-rotors all around
- New Ceramic Brake Pads
- New Rear Shocks
- New Tires all around balanced & rims checked

Road test scenarios:
- Vibration begins about 30 mph (1,000 rpm driveshaft RPM on tac in direct drive).
- Subsides about 60 mph (about 2,500 rpm).
- Shifting in neutral when vibrating & revving engine produces no change.
- Shutting engine off and coasting produces no change.
- No different symptoms when car is run on lift or jack stands.

About to lose my mind over this. TD

 

How "big" is this vibration? Is it that you are perhaps looking for perfection to the point where something normal seems unacceptable? If you do have a vibration, considering all that you have done, may be some shop's work is not quite up to snuff? Sorry, not much of a contribution but there HAS to be a reason! Where are you located?

 

Thanks for the response Lev. I am the shop, though now retired. I ran an independent Volvo shop some years ago and have solved lots of driveline vibration issues in the past which is why I'm SO frustrated. It isn't normal, nor something I can tolerate on an upcoming cross-country journey.

I'm located in Corvallis, OR and had the driveline balanced at a driveline shop in Eugene. Purchased new tires & had them balanced at Les Schwab, a NW franchise that has a good reputation. Next on my list of suspicions is a defective center bearing, new when balanced, although I can't imagine the driveline shop not noticing it accept that they of course didn't spin it under load or at any deflection angle. I just need to re-coop from my last driveline R&R which will be #5 without a lift!

BTW I forgot to say it's a '93 940 Turbo Wagon and I love the car. TD

 

So shifting neutral or shutting off the engine while moving and still not having any affect pretty much eliminates the drivetrain.

The rack and pinion steering is pretty built proof but I'd check for loose play, allowing some intermittent wobble.

Also, have you checked the front wheel bearings? How about your differential oil level which could affect your rear wheel bearing too?
How about your engine pan under your car. Is that secure at all points?

 

Thanks for the reply. So you think that even though the driveline is still spinning while in neutral and engine off, it would not be creating a vibration? Since it occurs on jack stands with front wheels stationary, I think that eliminates any front end involvement. I'll check differential fluid level although there is NO evidence of leaking at pinion or axle seals. I'm ready to consider anything, even the radio!! TD

 

I guess I should have said "from the TC back." I know my carrier bearing is going bad, getting a vibration too. It hasn't been changed for approx 200k and it's time.

I know you said turning off the engine didn't make any difference but have replaced your motor mounts. If like mine, there oil filled and go bad and decompress.

Have you changed out tranny fluid recently? If so, how does it look, color wise and smell?

Since you have changed out your TC, I would expect a good visual here.

Sometimes you can get a vibration due to lack of lubrication on the front of the driveshaft yoke, entering the rear of the tranny.
You might pull that and re lube.

You have a real stinker here!

 

A stinker it is indeed. I had the engine out for the 2nd TC installation, I suspected the first one was defective, and the motor mounts are very solid & clean. While the trans was out that time I replaced trans mount, seals, filter & gasket, and fluid of course. I'm having a transmission shop owner drive it this week and then run it on their rack. He doubts the issue is transmission related and he has no dog in my fight.

Thanks for thinking about this. As Lev said, "There has to be a reason!" TD

 

I'd question the driveline shop's work, simply because it's the most probable area where things could have been missed. I doubt it's transmission related. I am in Portland,OR; I'd run to Alamo if I had head scratcher like that... Keep at it, you'll get it, and I'd like to know what it is.

 

I go to Les Schwab too and like them, but I'd swap tires front to back and run it on stands just to make sure, Stranger things have happened.

 

Alamo in Portland rocks! my daughter took her 240 there a few times when she was going to school in Portland.

 

Well, to all interested parties, the "Great Mystery Vibe" has been solved in my '93 Turbo Wagon. EUREKA!! It is a(nother) lesson for me and hopefully can help others.

Everything ties back to a new, yet defective, center-bearing-assembly I purchased from my long time supplier, had installed by a good machinist, and went un-detected by an excellent drive-line balancing shop, twice, since the the drive-line checked out perfectly, but ... was not under load. I found a slightly bad new u-joint last week and when I replaced it (R & R #4) there was some improvement but I now suspect it was failing because of the defective Center-bearing.

It was difficult to notice the side to side play of the bearing in the housing, due I suspect to the ID of the rubber housing being oversize, yet it was rigid enough to hold the front & rear face of the bearing very snuggly until about 1,100rpm. Now that it's off the shaft it's difficult to make it shift side to side but I could plainly make it move on the driveline. I re-installed the original one (R & R #5) which only had displayed the beginnings of drying & cracking of the rubber support. The result was perfectly smooth acceleration and cruising thru 75 mph.

Beside the lesson of not taking new parts for granted is that I was caught by an aftermarket part. I felt that the risk of a bearing (name brand) in a study rubber mount that looked identical to the OEM part was a non-existant risk.

I will take a few weeks off before R & R #6 to install a Volvo part from IPD for $38. My local dealer quoted me $300 plus, up front & a week away!!! I'm really fast & good at this by now. "Old Volvo's never die they get newer part by part"? The Old Volvo Song

Thanks for the help. TD