1.0 Introduction

This information is meant to help others trying to convert their power steering equipped RX-7 to a system using a power steering rack, but no assist from a pump.  This will allow you to remove your pump, belt, pulley, cooling loop, etc from the car.  I am NOT any sort of expert on this matter, so follow my advice at your own risk.  I will say that I have completed this modification on my own car and it works great for me.

Important: I made my modifications when the engine was removed from the car so I had easy access to the steering rack without removing it.  Since you will probably not have your engine out, I think you need to remove the steering rack from the car to gain access to all the bolts and fittings.  Maybe not…. I’m not sure… but I’d imagine that you’ll run into clearance problems for wrenches if you don’t pull the rack from the car.

2.0 What to expect when you’re finished/FAQ

Probably the question that you’re most eager to know the answer to is “How hard will my car be to steer when I am done?”.  Just so you know, I have 225/50 R16 Toyo Proxes RA-1 tires on my car (This model of tire is particularly ‘sticky’).  Here are my thoughts on steering effort:

Dead Stop

Wheel takes quite a bit of effort to turn.  Definitely not easy, but you can do it if you just put a little muscle into it.  Not recommended if you have a wife or girlfriend that isn’t too strong! :)

Slowly Rolling (less than 5 mph)

Still very firm feel to the wheel and still feels pretty heavy.

Slowly Driving (around 15 mph)

Wheel feels like it has some weight to it, but can be turned with one hand as long as you have a good grip and are not some kinda wimp.  :)  Right hand turns are the only time where you think “Gee, this is kinda heavy!”.

Driving (25 mph and up)

Feels great!  Doesn’t really feel much heavier than it did before you take off the P/S pump.

3.0 How I THINK the P/S rack works

The P/S pump supplies high pressure fluid to 2 hoses that are connected down to the rack near the pinion.I have marked these in red in the diagram below.

Now, built into the pinion area is a 'mystery valve'.  I don't really know what it looks like, but let's just say that when you turn the steering wheel, it moves the valve and makes stuff happen.  

Now, also built into the pinion area are 2 metal lines coming out.  Each metal line goes over to a different position on the long part of the rack.  One goes to one end and one goes to kinda in the middle.

What happens is that as you turn the wheel, the mystery valve can distribute pressure from the 2 incoming high pressure hoses from the pump to the 2 metal tubes going to the two different spots on the rack.  I have colored these in orange.

Now, INSIDE the rack is some sort of partition or seal.  When one of the 2 metal lines (orange colored) is supplying more pressure than the other, it causes unequal pressure on the two sides of the seal.  The rack moves and your wheels turn.  That is where the "assist" comes from.  Don't forget, that even with none of the fluid doing anything, the pinion is still in direct physical contact with the rack, so that is helping a bit too and controlling the motion of the rack....

Now, just to throw one more thing in, there is an output from the pinion area that goes to a loop of metal tubing mounted in front of the radiator... then it goes back and dumps fluid into the pump again.  This loop is to cool your P/S fluid, as it can get quite hot due to the pump working on it.  I have colored this blue in the picture.

4.0 Problems and Solutions

Now, when you want to remove your P/S pump, you are faced with a couple of problems that you need to fix.....

4.1 The Problems

1) you need to make sure that pressure is allowed to equalize all the time from one side of the partition to the other.  Otherwise it may bind up... that would be annoying and potentially very dangerous.

2) you need to find a way to plug up the places that will now be 'empty' on your rack once you start removing all these lines....

4.2 My Solutions

These aren’t the most professional solutions, but they work for me!

4.2.1 Equalize Pressures

To make sure pressure is equal on both sides, remove both metal tubes (orange in my picture).  Don’t throw them away though, you’ll need the fittings.  You will be connecting the two fittings on the rack together and plugging the two fittings on the steering gear.

Then go to the hardware store and get these items:
 

One 1/4 inch “Tube Union” with inserts.- Straight type

One 1/4 inch “Tube Union” with inserts.- 90 degree angle type

About one foot of 1/4 inch copper tubing (you won’t use it all, but getting a bit extra is a good idea)
 

NOTE: In case you’re wondering about my tube unions… I got them at Home Depot.  They are made by a company called “Anderson Barrows” and are sold in little plastic baggies.  The barcode info on the straight type is 0-48643-07036-3.  Sorry, but I don’t have barcode info for the 90 degree bent ones.
 

Now, take your two metal tubes (orange in my picture) and cut off the ends with a tubing cutter.  So you will end up with 4 chopped off end pieces.  When you do this, leave as much of the straight part of the original end as possible.  The reason for this will become clear in a minute.  Check out this picture for help:

Now, using your nifty tubing unions, the copper tubing, and the two ends that you got from the factory tubes, make a little piece to join the two parts of the rack.  This is why you wanted to leave as much of the straight part as possible.  Then install it to connect the two parts of the rack.  Putting the bend in it is good for two reasons.  First, it helps it stay tucked away under the oil pan and nicely bends around the steering rack mount area and doesn’t hit on anything.  Second, you want to purposely make it JUST a bit extra curved and JUST a tiny bit too “short”.  The reason for this is that when you put it in you kinda need to have just a bit of flex in it to simultaneously plug it into two holes at one time.  The bend give you a little extra length on reserve if you need it.  Here is a drawing kinda like the one I made.  I could not get an actual picture because it is too hard to see:

I hope you see what I mean about having some extra bendiness in the thing…. Imagine trying to insert the above into BOTH fittings at once.  You’d have trouble if you didn’t have a little extra flex and length ‘stored’ in the bend.

4.2.2 Plug those holes!

So, now you can remove your pump, the high pressure lines, and the cooling loop.

OK, you will have 2 large banjo fittings that are now 'blank' (no banjo part) because you've removed the 2 high pressure lines from the pump.  These are red in the diagram.

I made two spacers out of Delrin (a type of plastic that you can buy; usually sold as long rods) on a lathe that looked just like the banjo part, but with no outlet where the hose would normally attach.  This was cheaper and faster than finding huge bolts and then matching threads and sawing them down, etc

The outlet going to the cooling loop is now blank.  There should be a hose with a fitting on the end, but now, it's just open.  This is blue in the picture.

You COULD buy a big huge bolt to go in there, but these aren't easy to find (near me anyway).  Since I was not planning on ever trying to 'undo' my conversion, I sawed the hose in half so that I could get the bolt/fitting.  Of course, that has a big hole in the middle for the hose that used to go there.  So I tapped the inside of the bolt/fitting

with a dirt-common size american thread and then bought a small bolt (sawed it down to fit) and put it inside the original one with some sealant.  Remember, don’t let the new assembly protrude into the steering gear area any farther than it came from the factory, or it may catch on something.  Then I put it into the hole.  Hey, not too professional... but it doesn't leak and is cheap if you already own a tap and die set!

You will also have 2 holes where the metal tubes used to come out of the steering gear area and go to the rack.  These were orange in the picture.  You can do the same trick as before…. Use your chopped off ends from the steps above.  Then tap out the center with whatever common bolt size and thread you like and plug the center with a bolt.  Then install the whole mess into the pinion.  Remember, don’t let the new assembly protrude into the steering gear area any farther than it came from the factory, or it may catch on something.

Check out this picture for what my steering gear area now looks like:

4.3 A few last things

OK, now after you’ve gotten everything squared away, you need to test this out with the front of the car jacked up.  Once the front end of the car is up in the air, insert your key and carefully turn the key JUST far enough to ‘unlock’ the steering wheel.  Now, move the wheel from lock to lock a few times…. Go slowly at first to make sure nothing is binding or catching.  Then go faster to make sure everything is smooth.  You shouldn’t feel anything sticking or catching.

Safety is important!Make SURE you can steer the car OK BEFORE you go on the road!
 

You may notice some beeping noises coming from under your dash now that your P/S system is gone.  This is the power steering control unit’s way of saying that it thinks the pump is broken.  Just unplug the connector and it will be silenced.  Here is a picture of the area under the steering wheel.  I got a lot of glare from the flash on the camera, so I outlined the shape of the box in red… sorry!  The power steering control unit is the large silver box.