s-cort shakes @ high speed

I was out on a car trip, and after getting brand spankin yokohama tires, and getting the whole balance/alignment job, my s-cort STILL shakes at high speeds.

The last pair of tires had a very strange wear pattern on the rear left wheel:
if you viewed the wheel from the side, instead of seeing a nice, circular tire, mine looked more like a 10-pointed star, only the points of that star weren´t straight points, more like rounded. In other words, the tread of the tire was really low in one place, then you´d travel along the circumference of the wheel another couple inches, and the tread was high again. It was like the tread was periodic wave extending itself along the circumference of the tire, if that makes any sense.

anyway, this problem totally baffled me, but the mechanic who changed my tires said that it was a problem with my not rotating the tires on time. He also said that it was because the back end of the car was so light that the back of the car would "bounce up and down" and cause that kind of tread wear. I don´t know if this is the case, or if he´s full of shit.

After driving several hundred miles, at speeds of 30-110mph I noticed that this problem is at its worst at about 65mph. The problem seems to go away once you get over 85mph, although I think that´s because it starts shaking so fast that you just feel it as a whirr and it just kinda blends in.

As a result, I felt that the problem was in the suspension. I felt that what was happening was that the suspension had leaked oil and become underdampened, so when I hit a bump, that bump propagated and was perpetuated somehow by the fact that my suspension couldn´t stop it.

My sister was in the car with me, and she thinks the problem is that a light car like the escort will shake because it doesn´t have the weight to keep the tires glued to the road, but she doesn´t know anything about cars.

Please help me, i just want a smooth as buttah pimpin´ wagon...



[ This message was edited by: siragan on 23-12-2002 16:06 ]

[ This message was edited by: siragan on 23-12-2002 16:07 ]