I haven’t had any time to test aerodynamic modifications over the past several weeks because I’ve been busy dealing with other maintenance issues—completely new brakes on the truck (if you’ve never seen inside a 30-year-old drum with all its original hardware and shoes, hoo boy) and bad wheel bearings on the Prius. But I have had time while I worked to think about lessons from these other aspects of vehicle engineering that might apply to how we think about the process of aerodynamic modification.
I put the new bearing in correctly, with no shims (and
subsequent measurement—see below—showed that this wheel didn’t need to be
shimmed in the first place. It was well within spec). A quick internet search
found the Toyota factory service manual directions for alignment which
contained the allowable specifications for rear camber and toe and the
direction not to use shims. I was pretty irate that this shop—a national
chain—had apparently ignored manufacturer instructions like it was no big
deal. I’ve had problems with this shop before, minor things like grossly
overtightened lug nuts (I had to use a 3-foot breaker bar to get the lug nuts
off one time, after bringing the car to them for a flat repair).