96 850 GLT Oscillating

Hello all

My 96 850 GLT wagon has developed what I can only describe as an
oscillating high speed vibration. When traveling on the highway at
about 70 mph, I get a vibration in the steering wheel that comes and
goes at regular cyclic intervals of a few seconds. Kind of like a slow
pulsing. It is annoying at best.

Any ideas where to even start looking?

Regards
Russ

 

No, but I have an idea what physical phenomenon might cause something
like that. Generally, when you hear a slow oscillation like that, it is
due to what's called a "beat frequency".

click here:

http://hyperphysics.phy-astr.gsu.edu/hbase/sound/beat.html

And scroll down to "Envelope of beat production".

It's like the slowly oscillating drone of a twin-engine turbo-prop
plane, caused by the engines running at rpms that are different by, say
10 to 20 rpms.

So, you probably have two rotating elements, each out of balance
slightly, that are rotating at nearly the same, but not quite identical
rpms. The frequency of the beat is F1-F2. Maybe your two front tires
are slightly different in radius (uneven wear, uneven pressure?), and
each is a little unbalanced?

Someone with knowledge of typical problems with your model can help from
here.

Java Man

 

The first thing to try would be to rotate the tires front to back and
see if that changes it. Easy to do and would tell you if a tire has
developed a problem.

More likely causes would be a bad front wheel bearing or CV joint.

John

 

Sure sounds like tire balance. Each front wheel is probably out of balance a
similar amount and there is a tiny difference in rolling diameter between
them. As you go down the road the forces on the steering alternately add and
subtract as the wheels slowly rotate with respect to each other.

A spin balance on the front tires should fix you right up. If a shop in your
area uses Hunter balance equipment you can be sure it is done right.

Mike

 

Gents

I'd like to thank all of you for your replies. I'm going to have the
tires rotated and balanced and see if that solves it. It has been a
year or so since that was done so it might not be a bad idea.

Regards
Russ

 

Russ:

I had have similar problems in different car makes (Volvo, Nissan,
Silverado, etc.) and in most of times is an uneven wear in tires, as
well as small deformations due to impacts, low preassure driving, and
such kind of things.

I know that also can be due to high mode vibrations, and if thus it may
be ought to a damage or deformation in chassis or body.

Best regards
Oscar

Russ ha escrito: