I've had this problem pretty much since I've had this car, and have not been able to diagnose it.

When driving, I get a noticable vibration anywhere from about 48-52mph. It seems to lessen under acceleration though.

I've had two sets of wheels on this car, it's done it with both. I had the original 14" steelies, and now I'm running 15" second gen wheels. No change between the two, and I just put a new set of tires on the 15's and it's no different. I don't think it's a wheel balancing issue seeing how it's spanned across multiple sets of wheels/tires.

I jacked it up today to checked for play in the balljoints and tie rods, and the car is solid as a rock.

It also has nothing to do with brakes, I've completely overhauled the brakes on the car, and it hasn't effected this particular issue.

Does anyone have any ideas? The car didn't seem to wear tires odd before, but I've been thinking about getting an alignment and seeing what that does.

 

Uneven tire wear perhaps. Could be blown front struts.

 

have u replaced the motor mount bushings? if u have did you use stiffer ones like the polyuritane (idk how to spell it) ones cuz i did and o my god it feels like my teeth r gonna fall outa my head at any speed but specificaly at 45 thru 140

 

The tires are brand new.

I have not touched my motor mounts.