OK my 95 Gl Wagon shakes at 60 MPH on up. Below that everything is tight and smooth. It feels like a vibration through the front down the center of the car, the faster I go, the more she shakes. The dashboard even bounces so hard it feels like its going to break in half. As sson as speedo goes under 60 all is weel again. I have new tires and high speed balance along with 4 wheel alignment. Also new sway bar links, subframe bushings, and right hub/bearing assembly are new. Ford says the front end parts are tight. When I got new tires though, they said one wheel took a HUGE weight to balance it. Is it possible this rim is bent? What other things could be the culprit and how do I test for it? It has 128,000 and still has original struts. Thanks if anyone could help, feels like my car is going to rattle aprt on the highway if I dont find what the hell is causing it.
Are you running the stock wheels? Take that wheel to a garage that mounts tires and see if it's still balanced. If it takes a massive amount of weight to balance it, I'd just grab another steel wheel from a junkyard (>$20) and get the tire remounted.
Did they put on/tighten down all the lugs? Have you ever had wheel spacers on the car before? Tires inflated properly?
Try taking the car up past 60, and put it into Neutral to see if it's a chassis problem or an engine problem. If the vibration quits while it's coasting at 60+, then you might have bad motor mounts. If the vibration persists, I'd go back and check the wheel balance again. Another unusual thing to check, which happened to me once, was a broken-off piece of rubber valve stem rolling around inside a tire. I bought a new set of tires, and the guy who mounted them was careless, and left the broken-off valve stem inside the tire, rather than taking it out. I had vibration problems until the junk was removed.
Also, you might put the front end up on stands, and run the thing up to 60 to see if the problem is in the front or rear.
Taurus & Sable with the regular dashboards (no console, steering column shift) are notorious for having horrid cowl shake, which makes the middle of the dash look like it's going to fly off. Mine bounced up and down over 2". Dealer said "it's normal"...