The Miata power steering is a "touchy subject" with some people. While most want some form of power steering, most find that the Miata's is overboosted. This makes it overly sensitive to small imputs, and unless you're really good at keeping your arm perfectly steady on bumpy roads, you can end up with it being more (rather than less) difficult to drive. This was what I experienced in my M1, and I definitely wanted to go to a manual steering to remedy it.
Lucky for me, the manual steering in the Miata can make it a bit difficult to parallel park, or navigate in slow urban environments. I came across a post on Craigslist (http://www.craigslist.org) of someone who wanted to trade their manual setup for power. After some negotiation, we decided to meet at my house one evening and swap setups.
Before swapping to or from power steering, there are a few things you should know. First, if you're converting to manual & have AC (I do), you'll need to get an idler/tensioner pulley to make it functional. Also, this will change your alignment, so you'll want to have alignment equipment on hand (perhaps I should post an article on how to align cars in the future...). Also, make sure you have the right power steering fluid on hand as you'll dump out all the old stuff (providing you're re-mounting the PS assembly).
For both cars, make sure the steering wheels are straight ahead & secured. Make all appropriate airbag precautions.
For the manual steering car, you just need to pull the steering rack with U-joint. Put the car up in the air, remove the tie rod ends (either remove them from the rack, or remove them from the spindles), remove the 4 mounting bolts, and remove the bolt attaching the u-joint to the steering shaft. With this done, the rack should come right out.
For the PS car, it's a bit more complicated. Remove the hose going to the PS resivoir & drain it into a pan. Unbolt it as well as the bolts attaching the "cooling line" (really just a line running to the nose of the car to cool PS fluid). For me, I had to remove the AC compressor to get to the next stage properly. Remove the 4 bolts holding the PS rack on, the tie rod ends (if you're removing them from the rack, count the number of turns to do so on each side), and the u-joint. Also, remove the fluid pressure hoses, which will allow the rack to come out. Remove the bolts & brackets holding on the PS pump, and pull the assembly out. You'll need to snake the PS cooling line out of the front of the car. Remember this arrangement, as it will help reassembly in the non-PS car.
With the assemblies removed, it's time to put the cars back together.
For the "new PS" car, put the rack in (make sure not to move it side to side). This would be a good time to replace the tie rod ends on both cars. If you're putting new tie rod ends on, you can "rough in" the alignment by putting the new ones on with as many turns as each of the old ones came off. Mount up the PS bracket & pump, and make sure the hoses & cooling line are routed correctly. Once done, tighten up the bolts, put in new fluid, and check for leaks. Afterward, you will need to align the car.
For the "new manual" car, it's pretty easy. Just mount up the rack with the 4 mount bolts, tie rod ends, and steering shaft bolt. I didn't replace the PS pump, but you can if you get the right idler pulley. I believe it's part number 15-970. Once it's all together, double-check everything, align it, and test drive it.
The result?
I liked it. I have a windy, bumpy road on the way to work, and with the PS, I was fighting how body roll or bumps moved my arm. With the manual, it's much easier to maintain the line through bumpy corners. Parking wasn't too much of an issue. I was most worried about how my wife would feel about driving a manual car, but she said she liked it better. Anyway, I couldn't be happier with the swap!
