Occam's Razor - In philosophy, Occam's razor is the problem-solving principle that recommends searching for explanations constructed with the smallest possible set of elements.
When I bought my 928 in late July 2022, she didn't run. I got the LH computer rebuilt and she fired right up. But I couldn't drive her until I got new tires, which I purchased on Labor Day w/e of '22. When I took her out for her maiden voyage, there was a vibration in the steering at 65-70mph. Phooey! But I had other items of more importance (and $$$), like timing belt and water pump replacement to focus on 1st.
Spring of '23 those items are replaced and now I can look for the shimmy. I'd noticed a growl in the right front that meant the wheel bearing was bad. That could cause a shimmy at high speeds, so I replaced both left and right front wheel bearings. The growl went away but not the shakes at 65. Rats!
Next up was front tie rods. Since they were 34 yrs old, it might be time to replace them. So I did. Still had the shimmy. Double rats! But now I needed to focus on getting the AC fixed.
Summer and fall go by without finding the AC issue. Then before Thanksgiving I buy a set of tires for my Cayman from the same big tire store on 170th & Maple. My 1st chance to drive fast was on the trip to my sister's for Thanksgiving in Dallas. It shook horribly for the 10 hrs to her house. While in Dallas, I had another of these stores rebalance the tires. The tech said the tires were out of balance. The drive home was so much better.
My focus shifts to doing the maint on the Spyder, getting it ready to sell, selling an 85 911 and 70 Chevelle SS for a friend, and doing registration work for 2 DEs and a club race. With all that behind me now (the Spyder's still for sale), I had time to pay some attn to the shark.
Today I took her to the tire store on 120th & Dodge and had them rebalance the tires. Tech told me they were way out of balance. Took her for a ride along West Dodge expressway and the shimmy is gone. 65mph quickly turns to 75 since the ride is so smooth. I called them up and thanked them.
Moral of the story - never assume something simple might not be the cause of a problem. Start there first (Occam's razor). I assumed since the tires were new and just balanced that that couldn't be the issue. Going with the simple idea first can save you a lot of money vs the parts cannon approach. (The rebalance was free.)
PS. Today's tech really liked my shark. How could you not?
