Hi all bricksters,

I am currently going nuts trying to figure out why I have a vibration at highway speeds in my 1994 Volvo Wagon. I recently got a new driveshaft installed by the dealer as the old one was stuck together (thanks to the dealers half-ass prior replacement of my cars center bearing). Everything seemed ok until I got the car up to 55mph or so and deep droning/vibration took over. I had the tires balanced and two rims straightened. The vibration still haunts me. There is NO shuddering at takeoff just the droning at highway speeds which is SPEED dependant. That is between 50 an 75 mph I get the vibration regardless of gear position or acceleration/deceleration. Rather than write a 4 page essay of the fixes I have tried I will list the details below:

1) Checked motor mounts and they look fine. No sag. Less than 1/4" inch between oil pan and frame.

2) Replaced transmission mount (the original looked fine btw and I probably wasted $50)

3) Checked driveshaft alignment/phase. I marked everything and took it apart to double check the dealers work. I discovered that the two sections only fit together one-way which appears to be correct (yokes align).

4) Output shaft bearing/seal are fine no tranny fluid leaking at all and even checked the seal which looked fine.

5) Center bearing is new and looks fine (came with the new driveshaft). Center bearing carrier is also new.

6) No play at either end of the driveshaft (i.e. no wobbling, signs of leakage or "clunking" when I shake the drive train.

7) All rear bushings look good.

8) As stated earlier I had the tires balanced and two rims straightened which solved a shake in the front end.


Overall, as far as I can recall the vibration started AFTER the dealer installed the new driveshaft. Which leads me to believe that the dealer did something or that the new driveshaft is somehow not balanced properly. I have tried MANY things as listed above and searched the brickboard and sweedishbricks EXTENSIVELY to no avail.

My final guess is that the tires are the culprit or that something in the driveshaft is not right. Any advice, info, suggestions would be GREATLY appreciated as I am about to go insane!

THANKS!

try swapping the wheels around, i know it sounds daft but see if it makes any difference...I had a vibe once that was noticable if the wheel was on the fron t but not the rear...

hey worth a try, might learn something and costs nothing...

Thanks for the suggestion. I think you are on target. I swapped the tires around today and raised the tire pressure. The vibration isn't gone but less than before. I am going to take it in for a balance (again!) at a good tire place.

when that happened to me it was a bent rim...worse when it was on the front...but could also be something in the tread or just a duff tyre...
or balance...

Thanks for all great the suggestions so far. After a long weekend of late nights in a cold garage I am going to go to another dealer for their opinion and possibly a wheel balance on a fancy new Hunter machine. So far I am still leaning toward tires/rims until I rule them out. Anyone in the Boston area got a fresh set of tires I can borrow for a day :)

IF its a rim or tyre (probably only 1 - or majourly one...) how about you swap each one out for the spare in turn....if it goes away (or lessens) you found your culprit!


ps i have found bent rims to be MUCH more noticable o nthe front than the back...you can have one on tha back and not really notice it...swap it to the front and your teeth fall out!

One last thing. I took the car back to the dealer and did a road test with a mechanic. They acknowledged the vibration but said some of the tires looked " a little out of round". I am looking into this but still not convinced as the problem did not exist before the dealer replaced the driveshaft.

I think this is the solution to pursue. It's like troubleshooting computer software...when the computer breaks, look closely at the last change you made, it's probably the culprit.

Vibration didn't exist, driveshaft changed, vibration now exists...something with the driveshaft isn't right.

Good luck!

BTW, I've spent the last 9 months troubleshooting a vibration in my 850. Turns out I've got a slightly bent wheel. But really, it almost has to be the drive shaft in your case.

Mike

unless they moved the wheels around when they did the shaft, or bent one of them...or over torqued it etc etc...

co-incidence exists as a word because they happen!

Ok, so here is a status report. I decided to put the car up on jackstands, remove the wheels and run the car up to about 55mph (carefully and without applying brakes). The vibration returned and it appeared to come from the rear-end/differntial area (I had someone run the car while I listened to the wheel well area. I messed around with weights on the driveshaft but only for a short while and without meaningful progress. The pinion seal looks fine as there is no movement when I tug on the driveshaft. I checked the differential fluid and it looks a bit foamy but is full. Not sure if the foam is a clue.

In anycase I am stumped and short of throwing more time and money away I am at a loss. I think I am going to give in and go to a dealer.

fraid i cant be much help when it comes to diffs and shafts...see if steve ringlee has any ideas he seems good on stuff like that!