High speed vibration

[snowjob]

Hi All
I've just bought a 91 legacy LS, 2.2 non-turb. FWD, when I bought it, the dealer put two new tires on the front, replaced both drive shafts and cv joints(inner and outer on both sides) and did the brakes. My prob with the car is that when you go above 90kps/55Mph, the car gets a vibration, I can hear in the car a thump thump thump.... and the steering wheel vibrates. The front alignment has been done and all 4 tires have been balanced. but it still vibrate any sugestions?
My second prob with the car is the steering is VERY twichy, if turn the wheel even a little while driving above 40, the whole car seems to jump in the oposite direction(I realize the struts are done, but this is quite suvere.) Anyway the car has 87000mile on it. Can anyone help me, i'm at a loss ...

Thanks
Frazer

[Legacy777]

Take your tires to another place and have them rebalanced or at least checked.

What happens if you put the rear tires on the front, do you still get the vibration in the wheel?

The twitchy issue is probably from a little too excessive toe out in the rear.

A 4 wheel alignment should help.

[rallysam]

I agree. Everything I would look into to fix your problems (balanced wheels, alignment, driveline problems, warped rotors) - you just had worked on. So, I am guessing they did something wrong. I would get the tire balance checked, get the aligment checked.

[ciper]

Maybe the driveshaft is out of balance, from a bad u-joint.

[evolutionmovement]

Check the tie rods for play with that twitchiness - could be toeing out.

Also, if the wheels are balanced again to no avail, it's possible that they could be flat-spotted or warped (like mine from striking curbs sideways in the snow).

Steve