i would think it is more likely due to a wheel bearing. the question is
which of the four. i ended up replacing all of mine at about 110,000 miles
because of a little shimmy in the front at high speed. the ones removed
just fell apart and did not require a press to remove them so it was good to
have done them all.

"Trent" > wrote in message
oups.com...
> I have a '90 Miata with a 1.6, I have only had it for about a
> month, I have started driving it on a regular basis to work and noticed
> a shimmy feeling in the car, I took it and had the wheels balanced and
> rotated over the weekend, but as I was coming in to work today, I
> noticed the shimming is still there, to describe the shimming goes
> something like this, at about 60-70 mph, the car vibrates for a time
> then stops for a time, it's like the driveshaft is unbalanced, after
> the wheels were balanced, the vibration in the car has stopped but the
> shimming has continued... does anyone know what the shimming may be...
> thanks for the help... Trent
>