I used the following for guidance:
http://www.flyinmiata.com/tech/depower.php
http://www.rx7club.com/showthread.php?t=942543
I'll focus on what's different between the Miata and RX7 rack as the theory behind it is still the same. Also, you can use the pics as a how-to on how to rebuild the rack. Instead of cutting things off, just replace the seals with a cheap rebuild kit. Much cheaper than a reman and these are fairly simple and EASY to remove from the car.
First you need to remove the rack from the car. It's easy. To outer tie rods nuts, remove the inners from the rack with a pipe wrench (keeps alignment), two rack bolts and a triangle-shaped connector at the firewall with a single 10mm bolt. Remove the high pressure line from the pump since chances are it's frozen to the rack and the return line. I had to cut the rubber as it was not coming off the cooler.
With the rack out of the car, start removing lines. I made do with a 7/16" flare wrench which was TIGHT. Assuming they are metric but I liked the bite with the standard wrench better. After the lines are off, be careful because any time you move the rack fluid will shoot out, even when you think it's finally empty.
With the lines out of the way, you need to remove the adjuster. This sets backlash and puts tension on the rack against the pinion:
Don't remove the plug in the center. It will break and seals the rack. I had to make my own at the end and seal with silicone.
Every rack is different and the XR rack was different than the rest of the how-to's I used. The adjuster is around 1 1/8" so came up with this tool. It's backwoods redneck haggard but it worked:
You need A LOT of downpressure, definitely a 2-person job and the hitch ball lets you do that without hurting your hand and someone can turn the top nut. You also need to remove the factory stakes with a chisel or punch so the nut can move. This is by far the hardest part of the entire job.
Adjuster out with the spring inside:
Everything out:
And the rack beneath:
Now you need to remove the pinion. Pop the dust cap off:
Remove the nut while holding the pinion from turning:
Before you tap the pinion out, on the top of the rack you need to remove the dust cover (mine was broken into 5 pieces already) and the snap ring above the bushing:
Gently tap the pinion out:
With the pinion out, you can now remove the rack from the housing. On the passenger side there is a large black bushing with two notches. You can use a large piece of flat stock and turn it. There is a notch in the housing. Turn until you see the wire clip. This needs to be pried out of the housing while you turn:
Turn until it's fully out and you can unhook it from the bushing:
The rack needs to come out the passenger side. Turn it in a vice and tap the rack out from the driver's side. I used a long rod that fit into where the inner rack screws in, but small enough diameter to not damage the threads. You need to HIT it, and watch your feet. Having someone either support the rack or give it a soft landing.
Move aside the housing the get the rack in your working area. To de-power the rack properly, you need to cut the seal off the center of the shaft. I used a cut-off wheel on a die grinder and finished with a chisel.
The actual seals:
Cut:
Clean the housing, rack and pinion off (I used brake cleaner) and then greased everything heavily. Assmebly is the reverse of removal. One thing to note, since the seal in the center of the shaft is gone, when you are tapping in the passenger-side bushing DO NOT GO TOO FAR. You need to line the hole for the clip up and there's not easy way to punch it back out unless you have a very large bar to tap it out.
For the fittings, I made a block off plate off the factory line holder and sealed with RTV. For the threaded fittings, I cut the lines flush and welded them closed.
For the adjuster, there's barely any tension on it from the weak spring so you need to stake it. I couldn't get it to stay, even with a couple. I added some 242 Loctite and then put a safety using washers and a screw that used to hold the lines.
To get the wheel centered, I took apart the coupler on the rack at the splined connection. Then with the wheel locked centered, I put the intermediate shaft on the firewall junction and then the rack in. With both wheels straight I connected the splined connection and tightened it.
After moving the pump, I relocated my ground and also made a bracket like factory to hold the lower radiator hose:
More room!
Cleaner under car too:
The car drives like any car with a manual rack. Not too light at high speed and anything over 5mph, even with 215-width sticky street tires is manageable with one hand. Overally, cheaper than buying a manual rack, drives fine, saves weight and clutter and you get to keep a good ratio in the car.
