A bit more progress on the power steering parts:
After much deliberation about steering rack length and bump steer, I decided to just keep it simple and try to keep the outer tie rod pivots on the line between the upper and lower control arm pivots. To do that I needed to finally get an accurate measurement of where the front suspension pivots are relative to each other. Sounds simple...it isn't. Everything is on a different plane, and nothing is easy to get a tape measure or even a plumb bob to. Then, an epiphany:
It took me a looong time to think of this, I've been trying to get these measurements off and on for a long time now. Happily, the laser level helped me to get a reasonably accurate sketch of the front end geometry:
The ends of the diagonal lines represent the control arm pivots. The middle horizontal line shows where the stock pinto rack is located (stock length is not shown). The upper horizontal line shows the stock miata steering rack length (approximate, really more like 25.8"). The rack would need to be mounted 1.84" above the lower control arm pivots to remain in its optimal position. This location is firmly in the oil pan. So, lets pick an easy mounting location and modify the rack length to suite. I selected 3/4" above the lower control arm pivot to give me some real estate if I need to move the rack up/down when fine tuning later.
All this means that the miata steering rack needs to go from ~25.8" to 24.75". However, as it is easier to make a rack longer than shorter, I decided to take 1.25" out of the rack.
First disassembly:
You can see where the pressure fittings are, and the seal that moves between them. If we shorten the rack and housing on the right side of the pressure fitting, and on the left side of where the end cap seals, we wont effect the operation of the assembly.
I was able to use the lathe to scribe 2 lines. 1 where the rack needed to be cut, and 1 where the finish length would end up. After cutting with the grinder I found that the case of the shaft was too hard to even face. So... the finish pass:
(If you plan to do either of these operations make sure you clean the lathe thoroughly afterwards. The grit can wreak havoc on the ways)
After that, bore the ID to 15mm, run in the cheapest M16x1.0 tap you can find online, and add the end features to match the original:
Stay tuned for the housing...