steering unsteady on straights, dives into corners

[pizxed off]

At about 120K miles I had a front end accident that pushed the right front tire on my '93 300ZX back slightly. The inital insurance body work replaced all the right front end parts, but afterward I began wearing out front tires very quickly.

More work was done, and the problem with undue tire wear seemed to go away. But my non-adjustable caster remained out somewhat (8.3 degrees, outside the 8.9 degrees to 10.4 degrees allowable range). Because the car handled properly again, and the uneven tire wear went away, however, I was satisfied.

Now, at 170K miles, I am noticing I don't feel as sure footed at high speeds as I used to. The car seems to want to drift around in its lane at speed.

And, in cornering, handling is fine up to a point. But when I get to that point, I get too much of a turn in, the same as you get when you corner hard on tires that are underinflated.

The Toyo Proxes R1Rs on the front are new, and are properly inflated. The Proxes R1Rs on the back have about 10K miles on them, and are properly inflated. The tire shop thinks the caster problem is the source of handling unsteadiness. Considering the high mileage, I'm wondering if it might not be something else, like tie rods, or some other worn out or broken part? I especially wonder this since the problem only recently started.

[t.mcginley.jr]

There's like a 98% chance that your stock tension rods are worn out. The original bushings are silicon filled and eventually deteriorate throwing your alignment/steering off. Someone did a little writeup of about replacing them:

300zx-z32-replacing-tension-rods-t220535.html

You can either replace the worn out bushings with new bushings, or replace the stock tension rods themselves with adjustable ones. Most people opt to get adjustable ones since they aren't too expensive (usually less than $150/pair). With adjustable ones, the soft silicon bushing is replaced by a solid pillowball setup which shouldn't really ever need replacing. In addition, adjustable ones are in fact adjustable, the alignment shop can set your caster now.