70mph vibration

[gmv]

On a 1998 Subaru Legacy station wagon (not the Outback) running stock tires and suspension, with a 5-speed manual transmission: I've been getting a vibration/droning at around 70mph +/- 3 or 4 mph. The problem occurs in gear and out of gear. A knowledgeable relative suggested it could be a warped or damaged rim that might have evaded tire replacement/balancing a year ago. My wife was in a fender-bender a year and a half ago that required some front-end parts replacement along with a blown front tire.

 

 

The dealer couldn't find the cause of this 18-month old problem. Any suggestions?

[mattocs]

When the front tire was blown all were replaced then, right?

 

 

Might need aligment...but if it ONLY occours around 70 and not anything over it it might not be...I dunno.

 

 

Perhaps when she had the fenderbender there might have been some bent things that were not fixed.

[gmv]

The tires were all replaced and the vibration continued.

 

When the front tire was blown all were replaced then, right?

 

 

Might need aligment...but if it ONLY occours around 70 and not anything over it it might not be...I dunno.

 

 

Perhaps when she had the fenderbender there might have been some bent things that were not fixed.

[jcniest5]

There is a way to test it by yourself without driving it. Jack up the car and use jack stands to support all four corners, start the engine, put it in D and (have someone) rev it to 70 and observe all the wheels/tires. You will really notice which one vibrates if any. That's how I found out that two of my tires were warped and since they all were three years, I replaced them all and now my car is running smoothly again.

 

Words of caution: When jacking up your car and use jack stands to support it, make absolutely sure that none of the jack stands can slip off (any corner from the vibration) since your car will be going like 70 MPH and if any tires and touch the pavement/ground, there's big consequence.

[SevenSisters]

I’m not positive, but I think jacking it up may be analogous to the one tire spinning when stuck in snow scenario. Even though the speedometer would read 70, the spinning tire speed would be 140.

 

Not sure, just want you to be safe. At 140, the tire could come apart.

[Suzam]

I'd consider finding a garage that is willing to put it on a lift and try this. MUCH SAFER! I had our MY95 on a rack and the mechanic put it in gear and let all 4 wheels spin.

:burnout: :burnout:

It look great from the back looking at it doing this. We drew a crowd to watch it in midair.

 

I would also suggest you have the rotors checked. They can cause vibration as well if they are warped. Is there a different kind of vibration from high speed while braking?

[Hocrest]

A bad U-joint or unbalanced propellar shaft can do the same thing, although these problems will usually show their sign over a wider range of speeds.

 

 

To check the U-Joints, get under the car (NOT RUNNING ) and just grab the shaft near the joint and shake itto feel for looseness. Then turn it, there is about an inch of freeplay allowed by the trans/diff, feel for a "binding".

 

An unbalanced shaft should be fairly obvious when the car is running up on a lift.

[gmv]

Thanks for the suggestions. I'll check 'em out!

 

 

gmv