When I turn my '97 Thunderbird’s wheels almost all the way it feels like I hit a small patch of ice. I did not take note of which combination causes, it but I am sure that it happens when I am backing up with the wheels toward the driver side. Does anyone know what is causing the quick slide sensation?
It’s the imperfections in front end geometry …scrub radius …whatever the new term is for king pin inclination.
When you back up you also have a “toe out” condition that gets worsened by the motion backwards. You probably have a slight static toe in setting. That is, the wheels are pointed inward slightly just sitting there. Forward motion “spreads” them outboard. In reverse, the tires/wheels are already spread apart outboard. The motion in reverse increases this spreading. Add extreme angles at limits of steering (keep in mind that you’re trying to make two different diameter circles while having tilt to them) and you reduce the contact patch enough for one to slip.
Get your alignment checked regularly. Take note any unusual wear patterns. Toe will be shown by 'feather edging" on the tread …biased in one direction or the other. In extreme cases it will result in “plowing” (toe in) or “wandering” (toe out) when at road speed.
Same thing happens in a cargo van. The wheels turn too sharply and drag. I learned to not turn all the way. Now I know of two Ford designs that do that. Oh well.