The steering was one of the few systems on my Miata that I hadn't torn into until this weekend, and I'm really glad I did. The passenger side steering rack mount was only finger tight! Not so good, definitely contributing to steering sloppiness, and it could have made life REALLY suck if it ever came loose.
So, here is the whole steering rack assembly out of the car and ready for surgery.
I cut the lines out and crimped them, took everything apart and greased the rack up, readjusted the rack preload tension, took out all of the power steering valving, and cut off the power steering seal. I notched it on two sides with a cutoff wheel, and then split it with a chisel. No damage to the steering rack!
Then I welded up the steering pinion shaft. As one might expect, ductility of this weld is paramount. It's unlikely that strength will be an issue (as the only torque it will see will be from the steering wheel) so I braze-welded it with silicon bronze filler. Turned out pretty well I think.
And here is the whole assembly ready to go back into the car. I didn't have extra wire to re-tie the inner tie-rod boots back on, so I used 1/16th aluminum welding rod. Worked like a charm.
You can see all the lines are gone (hooray!) and after a bunch of futzing around I got it back in and re-aligned the car. I think I'm going to have to fine-tune the alignment a little bit more, I don't think the rack is as centered in its travel as I would like.
All-in-all a ridiculous amount of improvement in steering drag, feel, and responsiveness compared to a simple by-pass de-powered steering.