98 Park Ave Ultra has a shimmy
 

My PA Ultra has a strange vibration at all speeds. It feels like a side to side shimmy. It's usually worse when slow but it's confusing because it doesn't always feel speed dependent.

I have already had an alignment and a tire balance and rotation done but it did not solve the problem. The alignment shop said my tires probably weren't very good to start with (Goodyear Viva 2) but they only have about 10k miles on them and there weren't any problems getting them balanced. I can't afford to replace tires when they have that much tread on them. All the work made the shimmy a little less severe but it's still noticeable. Changing out the power steering fluid helped the feel at the steering wheel but not much else.

What else could the problem be?

Try rotating the front tires to the rear and see what happens.

If no change, then raise the front end of the car off the ground(jacks under uni-body, not suspension) and check for wheel play at 9 and 3 oclock and 12 and 6 oclock position.
If nothing found, check tie tods for play. Up-down play, side to side etc.

i agree with mike about checking it over. you get those tires from walmart?

Yes, these tires were from Walmart originally. The receipt for the tires and the lifetime balance and rotation plan were in the glove box when I purchased the car. Walmart honored the service plan but I had to insist that the tires were actually rebalanced. Three of the tires had new weights in a different location so I presume they did the job even though I wasn't in the shop to witness it.

the walmart goodyears are junk and noisey, check over your car to be sure but ive had two sets do exactly what you are talking about. im not going to buy any there again.

I had a similar problem with my 99 PA Ultra about a year ago. After much work on it, the front wheel bearings were replaced on both sides and the problem went away. A year later, and still no more shimmy problems

Forgot to add that I have used Michelin tires from COSTCO for many years and have never had a problem with them.

Wheel bearings, tie rods, ball joints, tires with belt seperations ...

Rotate the tires (front to back). If the problem does not go away, jack up the front end and feel for play to indicate bearing or tie rod failure.

Thanks guys. I will jack up the tires and feel for play. I would be in over my head to go further than that right now.

I jacked up all 4 corners and found some play in the front drivers side wheel. There is maybe 1/16" of play when the wheel is moved side to side. No squeels or squeels, and I don't know where that tire was rotated from, but the problem did not change when the wheels were rotated.

If this is a wheel bearing issue how difficult are they to change? I don't know much beyond changing brake pads on a car.