Have been trying for many months to fix a shimmy in a friend's 1990. We've replaced struts, strut mounts, steering rack, tie rod ends, rear a-arm bushings - all were poor. Ball joints, steering u-joint are fine; wheel bearings are to spec. Tires have been swapped a couple of times.

The shimmy - felt in the wheel - occurs in 2 situations:

1) From 45 MPH to 20 MPH when braking. There's always some vibration and it seems worse after the car's been driven. We replaced rotors, pads. Calipers move freely. Pads and pins are new.

2. On occasion there will be a shimmy ~ 65 MPH. If you slow to 55 and speed back up it usually goes away.

Road surface seems to make no difference. It seems worse with the wheel straight - it's diminished when turning.

It's been like this for 15K miles. It's fine for him but he wants his daughter to take it to college and would like to know what it is.

Possibilities?

a) We happen to have gotten 2 sets of out-of-balance tires.

b) One of the wheel bearing races has a bad spot. I've inspected both but

c) There's something loose in the steering rack that we're not seeing in a static state.

I just drove the car ~ 40 miles - mostly highway - and it was fine, except when we slowed to exit.
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240s: 2 drivers and some parts cars