Thanks for any information anyone can provide. I am at the end of my rope dealing with this problem.

The car was purchased new and has this problem from the onset. It hadn't seen much highway (65 to 75 mph), use so I have only "chased" the phantom once a year; mostly it's driven at below 55 locally ... hence, it's (the problem) dragged out.

Odometer is at 67,000 miles.

Problem: At 65 mph an annoying vibration starts that can be felt through the steering wheel, the pedal, seat and floor. Relatively smooth (Interstate highways), new smooth roads etc. it's still there. It's hard to cruise at 70 mph, it's constant.

When the car was new the dealer replaced the tires (at 15K) and blamed the problem on Continental. Two sets later (my cost) and the problem always came back.

The car has no accident history and I've hit no pot holes or curbs.

The car has had wheel balancing and alignments. It's on it's 5'th set of tires (I think), I lost track counting.

About 7,000 miles ago, I switched to Goodyears, (balance and alignment included) .... but my local mechanic noted that at 1,000 miles the rear tires were slightly "feathered" on the outer edge of the rears. Seems to be a common "theme" (feathering), on every set of tires.

His possible "fix" is to change the rear shocks ($1,100), and another set of tires. One a few occasions I have wondered about the car (when parked), sitting at a "odd angle" (self leveling problem?).

With a change of jobs, I now have to "commute" over 1,500 miles a week on the Interstate at speeds of 70 and above. I have put $$$$$$ into this car chasing the problem and I'm reluctant to toss another $1,600 at what what sounds like a "hit or miss" approach. My mechanic indicates that he isn't sure what the problem is .... he did a full balance last week and said he ran the car on the lift to check for bent rims.

PS .... my wife is gonna kill me ... she has to be in the car with me for a lot of these trips and is now on to the problem. I had kind of kept her in the dark about it.

Signed, ..... "In Hot Water"!

Silly question....

How are these tires being balanced? For the best high speed performance, the type of balancing (hard to find sometimes) is the type that uses a roller to spin the tire while mounted on the car. That might, in this case, also show whatever else in the rotating mass is noticeably out of balance, since the discs and halfshafts would also be spinning.

Another option might be to try to locate a dynamometer center which would enable the car to be run up to speed under load, thus perhaps enabling them to locate the problem.

But I gotta tell ya, my money is on the problem coming from an imbalance of the rear drive shaft... does the vibration go away at around 80-85? If it does, that would strongly indicate a harmonic vibration relating to a part rotating much faster than the tires...

Good luck

Marty
'96 855T

Marty: I haven't had the balls to take it up to 80 with the wife and kids on board.

I'll be on the phone tomorrow to see if Volvo will share any info and will ask the shop about their balancing gear .... it sounded pretty new and "high tech" and they did put it on the rack and run it.

There was a problem with Saabs back in the late 80's. They were chaining them to the floor of the decks during transport and bending the axles ... I guess anything is possible.

It's starting to sound like a design flaw, but I did everything "by the book" changing all of the tires at once.

Kind of a shame because other than that it has been a very reliable car.

I'm going through the same thing with my '98 AWD. The thing is, I've done all the things you did. Then, to eliminate the high dollar possibilities, pulled the front-to-rear driveshaft and viscous coupler. Still there. You can really feel my problem (terrible shake anywhere over 65mph) starting in the back, though, even though it shakes the whole car. I just went under to examine bushings/shocks/hubs etc. I'm putting new rear rotors/e-brake shoes/pads on even though the rotors seem fine (no pulse when braking, thick, good pads) but the e-brake shoes were missing a lining and the rotors did look "hot" at some point. I hope it goes away. Have a friend with a '98 V70R with a similar problem and she needed a new right rear drive axle. I know I'm not really answering your question but just letting you know that you might only be a brake job or an axle away from eliminating your problem.

Worst case scenario, really high-end driveline shops can do dynamic balancing of the entire drivetrain with the car on a lift. It's not cheap but may be less than replacing parts looking for the phantom. Or just keep it at 60mph and get there later than you expected, with your wife glaring at you the whole time like mine does when I drive too slow!

Good luck...I'll check back if I get mine fixed and let you know.
Mike

Dragwagon: Thanks for the response. It doesn't sound like there will be a silver lining in this cloud.

I do have some pulse/wobble during brake application toward the upper speed range (initial application), then it reduces.

I'll keep hunting and will post any info.

Rear drive shaft has been recently replaced and this problem occurred.
Vibrates at 60-65MPH only. Possibility is the rear drive shaft need balacing.
Will update, when I get the car back from shop.

Marlon