I have this problem too.
My 2014 i3 Rex has 95k miles.
This weekend I replaced both front struts and springs with less-used from a 2017 Rex that only had 20k miles.
I bought and installed brand new strut top mounts, rubber boots, top nuts and bump stops.
I was really hoping the strut top mounts would solve it, but so far I can’t tell there’s any change to the non-self-centering.
Since I have lifetime alignment from Firestone, I’ll get it aligned again this weekend - has not been done in a couple of months. But again I’m not expecting a huge change.
The new-er struts definitely feel smoother and more consistent than the old. Highway driving is slightly less harrowing, altho keeping the wheel centered can still be a challenge.
Last month I added 20mm wheel spacers only to the front wheels and that actually made a huge difference - it’s much more stable at high speeds, but no change in self-centering.
I did notice when I had the front end jacked up off both wheels that I couldn’t push the wheels by hand to move them left/right. I think I checked with the car in ‘on mode’ but not totally sure about that bit.
When I had one of the old struts removed (I did just one at a time) it was pretty easy to move the wheel hub around so I didn’t get the sense it was due to a ball joint issue.
None of my tie rod boots, steering rack boots, or ball joints looked damaged or showed signs of leaking grease.
A couple months ago I removed, cleaned, and re-greased the u-joint at the base of the steering column.
There was no resistance in the steering wheel while it was disconnected, tho I did tie a nylon strap between the wheel and side mirror to ensure that I didn’t spin it around and damage the clock spring inside, or get it misaligned with the shaft where the unjoint bolts on.
The non-self-centering issue may have existed for the entire 2.5 years I’ve owned the car…
But I first became aware of it after rebuilding my AC last fall.
When lowering the car off of an undersized floor jack, it fell suddenly off the jack and maybe 4-6 inches to the ground.
I was using multiple, stacked bits of wooden 2x4 as shims to get the car lifted higher up (bad idea), AND the release mechanism to lower that jack is sticky & kind of all-or-nothing… so it was just a bad combination all around.
One thing I noticed that pointed me towards the ujoint, is that when I flushed the AC evaporator in the dash, the output of the cleaning fluid came down the steering column.
I thought perhaps it degreased and/or gummed-up the u-joint in the process.
It was dirty and had some rust.
I cleaned, re-greased with a very thick brake slide grease, cleaned up the rust with a wire brush and spray painted the metal to help protect it.
Steering felt slightly easier after all that, but it was subtle enough that I could be imagining it.
I feel like each change I make offers slight improvements but I’m still missing a smoking gun that would explain it all at once.
I’m very interested in this thread, and really want to find a solution both for myself and others.
EDIT to add: I now own & use a properly sized floor jack, after driving the front wheels up onto ramps that lift the car fairly high to start with.
This makes everything much easier and safer. I wish I had bought a good jack and ramps 10+ years ago.
but yeah it centers after pulling off. I'll try it, too.
