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Ok, now that we got the slop out, there's still some friction to get rid of. The passenger's side of the steering rack acts as a hydraulic ram, carrying a piston that slides between two seals. Each of those seals adds a little friction, but the big problem is the piston. The whole point of the piston is to trap a volume of hydraulic fluid between it and one of the seals. Now it's trapping air, and if you don't have looped hoses, then when you turn the wheel, you'll be compressing air. That's not gonna feel good.
The rack pulls out the passenger's side of the housing, but how it pulls out varies depending on who made the rack. Snap rings seem to be a common solution, but not for our friends at JKC. They use this big threaded rack bushing here.
Notice how those threads look all jacked up? That's because I jacked them all up. It turns out there was this little locking dent pounded into the rack to keep things from ever coming apart. Since it was buried under sealer and 15 years of schmoo, I didn't see it until after i had dragged all those aluminum threads across it. If you're tearing down a JKC rack, clean off all the goo first, look for a little ding like this, and cut it out with a grinder. Trust me, it's not any fun trying to get the rack back together with threads like that…
Even with this aluminum doojobbie out, the rack still won't come out. Remember that piston and those seals? The piston runs into the passenger's side seal when you try to remove the rack. No biggie, just find something long and stiff, use some hydraulic pressure, and press the rack out. The piston will push the seal out.
Of course, there's still that other seal way down there at the other end of the rack. I decided that one should just stay. Remember how I was saying a little rack friction is good. Yeah, we'll just say that's why I left it there…
Ok, here's the piston. That snap ring really seems like it should be the way to get the piston off, but I couldn't figure out how. Turns out I didn't need to, since I was standing in the middle of a machine shop at the time. Remember, there's no need to get the piston off completely, you just don't want it to make a seal, so it can't trap air. Ideally, you don't want it to touch the walls of the rack tube at all, either. Friction, you know…
Simplest thing to do, if you're standing next to a lathe, is just cut the piston down a bit.
This is more than enough to keep the piston from causing us any trouble.
That's basically it. The rack is now slop free, and very low friction. Assembly is the reverse of disassembly, as they say, except that you should clean things much better and use lots of grease. The only last detail you need to consider is what to do about all those hydraulic ports that are now open. The ports on the steel rack tube should be cut off and welded flush. Odds are, the Hayabusa engine case will be close enough to the rack to make this important. The ones on the pinion housing can be welded shut or plugged. Since I'm not so cool with the aluminum welding, I chose to plug them.
First, I grabbed all those hydraulic fittings out of the bucket and cut the ends off the lines.
Keeping the end of the line gives you the flare that will perfectly seal the pinion housing. Why I care is beyond me. There is no pressure in the pinion housing, so there's no reason anything would be trying to leak out past the threads, but with these little flares in there, by God, nothing is getting out!
Finally, I grabbed some little, round scraps of steel form the floor around the nearest sheet metal punch and welded the fittings shut.
If this rack doesn't look enough like yours, try Flyin' Miata's de-powering guide, which was done on one from a different supplier.
That's the end of the story, stop reading and go weld something.
All the Miatabusa you can handle:
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3 comments
Great write up! The note about drilling out the dimple to prevent the end cap treads from being destroyed was really helpful!
You don’t know how happy I am to find this write up! My rack 90% stripped but spent a good hour last night trying to figure out how to get the rack out of the gear housing. Got the Ali nut off but the rack wouldn’t slide out like all the other videos and guides I’d previously watched.
Got a press at work so had this in mind but didn’t want to force anything if there was something securing it in place that id missed. I can press it out tomorrow now with some peice of mind so thanks.
By grind out the dimple, what exactly do u mean? do u grind the outside of the rack down where the dimple is with an angle grinder?