I've been reading quite a few posts on this phenomenon...My brick developed a -bad- steering wheel shimmy during the winter; was told there may be ice packed in the rims, & if it didn't improve, to have the wheels balanced. Happened primarily at low speeds (25-30mph). Brought the car to a tire place - showed severe uneven wear to right front, & a nail in the right rear forced swap of left front to right rear and 2 new fronts. Balanced fine. Had a four-wheel alignment done the next day - diagnostics showed right front toe out was way out of adjustment - minor adjustment to left front, rears fine. Mechanics said everything looked tight on the front end - I explained that in the last year I'd had both left front inner & outer tie rod, right front outer tie rod, right front ball joint, and steering knuckle replaced. Also had a new OEM caliper put on right front since old one seized. For 2 weeks, all was well - no shimmy. Then, shimmy starts to reappear, intermittently - 20-30mph usually. Return to tire place, right front wearing fine, both fronts perfectly balanced. Return to have alignment checked, and right front toe out is out of adjustment again - not as badly as it had been, but had the alignment re-done for free. Yesterday had a 100 mile round-trip commute at highway speeds, and shimmy/vibration very noticeable at 75mph - same low-speed shimmy as well. Doesn't seem to occur while braking (it did before the new tires/balance/alignment).
Since I've recently had tie rod ends, ball joint, steering knuckle, and right front caliper replaced, and the mechanics tell me nothing looks worn out, is this something I should have the dealer assess? My biggest concern is safety, naturally. Someone on here posted about the sway bars - sounds expensive.
Thanks for your suggestions.