How to "depower" a Miata steering rack
If you want the fast ratio of a power steering rack with without the power assistance, you have several options. You can simply unhook the power steering belt but this leads to very heavy steering. The seals inside the rack are still trying to move fluid and the pump is in the way.
The next step would be to loop the lines around so that there's little resistance, but you're still pumping fluid.
The best way to do the job is to disassemble the rack and take the internal seals out. Here's how, starting with a rack that is already out of the car with the tie rods removed. Please note that this tutorial was written years ago using a 1990-95 rack. Later racks may require different methods of disassembly. It also does not address welding up the flex joint in the pinion.
This is the quick and easy way to "depower" a rack.
Here's the hard way that we prefer. Remove the adjusting cover. Start by undoing the large locknut, then the cover, spring and support yoke. The parts are laid out left to right in order of removal here.
To remove the pinion shaft, start with this snap ring. It's underneath a plastic dust boot.
Once the snap ring is off, flip the rack over and put it in a vice. Remove the cover to expose this nut. Really, there's a nut under that grease. Undo the nut and then tap the pinion shaft out of the steering rack housing.
Everything we have removed so far.
The steering rack is held in the housing by this stop ring. It is at the end opposite the pinion shaft. Use a punch through the hole in the end of the housing to pop it free. Some model years use a different technique for holding the rack in place.
The steering rack can now be pulled free. The enemy seals are now exposed! Pull the large cylinder off the shaft.
Clamp the shaft into a vise - pad it so it's not damaged. Carefully cut the seal from the shaft. In this case, we used a grinder to cut most of the way through the seal and then whacked it with a chisel. Perfect, no damage to the shaft.
There's the hard part done. Now we reassemble.
Now that the internal seals are gone, we don't need the lines anymore. One way to block them off is to simply cut the tube and crimp it shut. We're not trying to hold pressure here, only keep the dirt out.
Another option is to grab the welder and just put a blob of weld in the hole of the fitting.
Before re-inserting the steering rack, make sure it's well greased. Slide the big cylindrical holder over the rack. Once it's in place, pop the snap ring back on.
More grease! The pinion shaft goes back in. The cylindrical holder that's visible at the bottom of the picture is supposed to be inside the housing, remember? Not like in this picture. Torque the bolt at the bottom of the pinion shaft to 25 ft/lbs and then the cover to 35 ft/lbs.
After inserting the parts in the correct order, torque the adjusting cover to 43 in-lb three times, then back it off 25 degrees. Holding it in place, attach the locknut. Plug up all the holes with your modified fittings. And just like that, you're done.