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Rebuilding the Control Valve
The section below pertains to the typical 1960-1978 Ford/Bendix Control Valve & Ball Stud assembly
Rebuilding a Ford/Bendix Control Valve assembly is seldom an easy thing to do. Most shop manuals make it look easy, but that is true only if the parts you have to re-use are not damaged from rust or wear Before you consider or attempt a rebuild, there are some problem areas you should be aware of. This first part is not designed to scare you off from attempting your own rebuild (well, maybe just a little), but to show you what you may encounter along the way. I have done hundreds of control valve rebuilds and see these problems on a daily basis. These are the things not mentioned in any instruction sheet or shop manual.
1 )  Typically, most control valves found on cars today are not the original units with the original components. Many valves have been swapped off of different year and car models from junkyard cars and such. Often some of the pieces have been changed out somewhere along the line. The valve may have been previously exchanged with a rebuilt unit which in itself may have been pieced together from several different units. While most Bendix valves use many of the same parts throughout its production, many pieces are different and uniquely designed for certain applications. Granada parts are a popular swap item these days, but many Granada control valves (though identical in exterior appearance) are quite different from other valves by not having any reaction valve components at all. Even some new reproduction control valves contain parts that are of poor quality and design and should be changed out during a rebuild. Be aware that the valve on your car may not be correct for the application it is being used on and some parts may need to be changed in order for the valve to operate properly.
2 )  You cannot always rely on the plan to reassemble the valve based on the way it was assembled when you took it down. Many valves have already been improperly assembled by a previous owner or mechanic, even sometimes professional rebuilders. Depending on the brand and distributor of the rebuild kit you buy, the included instructions (if any) are likely to be fair to worthless. Many kits are sold with a generic instruction sheet that has been through so many generations of photocopies as to be practically illegible. Even the instructions and illustrations found in factory Ford shop manuals have mistakes and inaccurate information. Sometimes the information given will not even work on the year and model valve the book claims to cover. The most important thing to remember is that typical kit and shop manual instructions were originally designed for mechanics that worked on these valves during a warranty period or reasonable time span from when the car was new. They do not address the problems and situations that can come up on rebuilding a 25-40 year old valve that may or may not be complete, original or in rebuildable shape.
3 )  There are several problems that often damage a control valve due to physical enviroment and mechanical action. One such problem is rust corrosion due to water getting inside the hydraulic system itself or inside non-pressurized areas of the valve. It may not seem likely, but water inside the fluid system is a common problem. Water tends to get in no matter what, and in the power steering system, tends to settle in the lower components, such as the control valve. This can cause the valves inside to rust and pit, which can cause seals to fail, pieces to stick and parts to freeze up completely. More commonly, water gets in areas not a apart of the pressurized areas and affect parts not even benefitting from the washing action of the fluid system. Keep in mind that the control valve sets under the car and catches a lot of water thrown up from the road. During certain turning conditions, the drivers side tire literally drenches the valve with water and spray while driving. Examples of these problem areas are illustrated below.
4 ) The steering linkage is also subject to physical abuse in many areas. Most of this is caused by bottoming the valve or linkage on something, but some years may have damage simply because the wheel alignment was improperly done. A lot of physical damage is done by owners and even professional mechanics during removal and aseembly of the parts on the car. Proper use of the proper tools is important to avoid this damage. Never use a "pickle fork" to separate steering linkage. This tool alone is responsible for most of the physical damage we see each day. Using it will damage parts and may make them unusable.
Problems You May Encounter  ( And not really be aware of )
Rebuilding the Control Valve
Can you rebuild your own control valve? It depends. It depends on the condition of your control valve assembly, how you remove it from the car, how good of a rebuild kit you are using, and how good the instructions are. Any one of these items can cause you trouble and most valves have more than one of these problems during a rebuild. The biggest problem is - you don't know what condition your parts are really in until you remove the assembly from the car, tear it down and inspect it. By that time you are into it pretty deep and will have to decide whether to continue on your own or turn it over to a professional.
By definition, a rebuild means that there are some parts you will retain while reconditioning them to proper working order. There are several important parts inside the control valve and ball stud assembly that are not a part of a rebuild kit and these are the parts you hope to reuse. Unfortunately, these parts are often damaged due to rust, wear or improper removal/installation, and so have to be repaired or replaced to make for a successful rebuild. We will start with the parts that are universal to all control valves and those parts that are most often damaged.
The Spool Valve moves back and forth inside the control valve housing, distributing the pressurized fluid where it need to go in order to turn the car. The motion and location of the spool in the housing is dictated by the Ball Stud on one end and the Centering Spring on the other. The Spool has a seal on each end. When you have fluid dripping from the valve (that is not coming from a hose connection), it is usually due to the failure of one or more of these seals. The ends of the Spool go through the seals and leave the ends of the Spool exposed to moisture.The seals leak due to two basic reasons: 1) the seals have become worn and hard from time and heat (which causes the hard seals to scratch the surface of the Spool and leave "stretch marks"), and 2) the ends of the Spool are damaged and have torn up the seals causing the leak. Because it is possible (and likely) that moisture has gotten to to the ends of the Spool, the sealing surface is often pitted from rust and corrosion.
The pictures to the right show Spools that have the ends pitted from rust. While some people will wire-brush the ends and reinstall it with new seals, this is a waste of time as the rough surface will quickly damage the new seals and start them leaking again. Removing rust is not enough. The seal surfaces must be smooth with no pitting or roughness.
Spool Valve - Rusted Ends
Spool Valve - Stretch Marks
Spool Valve - Stretch Marks
The pictures to the left show a Spool that has "stretch marks" on the ends, caused by hardened seals and abrasion from dirt and corrosion. Left as they are, these grooves will cut the seals up and cause them to leak.
About 7 out of 10 control valves that come in for rebuild have Spool Valves damaged in one of these ways. Since it is not acceptable to reuse a Spool in this condition, it must be repaired or replaced. In most cases the ends of a damaged Spool can be re-machined to provide a fresh, smooth surface. However, there is a limit as to how much can be machined from the spool and still seal. In a few cases, the Spool is pitted so badly that it can no longer be machined and still hold a seal. In this case, the Spool must be replaced.
The Centering Spring sits to the outside end of the Control Valve, underneath the Aluminum End Cap. Its job is to provide tension on the Spool Valve and keep it centered in the valve housing. The adjustment underneath the cap changes the tension of the Centering Spring on the Spool. This adjustment and tension is critical to the proper working of the control valve.
Rusted Centering Spring
The problem associated with the Centering Spring is rust that is caused by moisture getting into the area under the cap. Sometimes water gets past the o'ring seal under the Cap, and sometimes the water travels from the Ball Stud, all the way through the hole in the center of the Spool, into the area under the Cap. The Centering Spring rusts, causing pitting and flaking of the hardened metal. This changes the tension of the spring and it can no longer be adjusted as stated in the shop manual. If the Centering Spring is rusted or pitted, it must be replaced. About half of all control valves brought in for rebuild need a new Centering Spring. Usually does not come in any rebuild kit.
Spool Valve - Rust Pitting
With the exception of some late Maverick and Granada control valves (which use o'rings), all Ford control valves have removable seat inserts for the hose ends to seal against. Original seats (and most replacements) used soft aluminum seats which seal easier against the steel tubing. Some replacements seats (and seats used in the manufacture of reproduction control valves) are made of brass, but are basically the same.
One of the most common complaints is that the control valve leaks from where a hose goes into it. People will often put sealers or Teflon tape on the threads of the hose fittings in hopes of stopping a leak. This does no good at all. The seal is accomplished by the sealing of the tube flare against the surface of the hose seat. The threads of the fitting do not seal the hose. They are not tapered pipe threads. The threads of the fitting are only intended to tighten down the tube flare against the seat. If you use a sealer and it seems to stop the leak, it is actually the re-seating of the hose that fixed the problem, not the sealer.
Because the seats are soft aluminum, and the hose tube is steel, the seats can be damaged quite easily and will leak. Seats are damaged mainly by over-tightening the hose fittings. When new seats and hoses are used, the fittings should only require moderate tightening to seal properly. People generally tighten the hell out of the fittings and this causes the flare to cut deep ridges into the seats. Many times the fittings have been tightened down so hard that the hose flare itself is distorted and will no longer seal, even on a new seat.
Most control valves have had numerous hoses replaced and reinstalled over the years without ever having the tube seats replaced. This means the seats have several different ridges cut into their surface and may no longer seal, even to a new hose. A heavily damaged seat may even damage the flare surface of a new hose, causing it not to seal properly even after a new tube seat is installed.
Many rebuilders (even national name brands) do not replace the old seats during a rebuild, and most rebuild kits do not come with new seats. For a proper rebuild, new seats must be installed. Some rebuilders drive the seats into the valve housing. Even the Ford manual says to press them in by turning a bolt down onto them and forcing them into the housing. Of course, this just tears up the seat and flakes off little bits of aluminum that can contaminate the valve workings. The only proper way to install seats is to press them in using a tool that does not disturb or change the smooth flare surface of the seat face, leaving it perfect for the hose flare to seal against.
Hose Tube Seat Comparison
The Sleeve is the tube area where the Ball Stud and the Ball Stud Bushing slide back and forth. On V-8 equipped 1965-1966 Mustangs (and some early Falcons), the Sleeve area is part of the Centerlink.
1965-1966 Mustang with V-8
Power Steering
1965-1966 Mustang V8 Centerlink
Sleeve part of centerlink
All other Fords had a Sleeve that was removable from the Centerlink. On cars before 1967, the Sleeve was a straight-tube and varied in flange configuration between car lines. Starting in 1967, all Fords used a tapered-tube Sleeve that was the same on all models.
1967 and later Ball Stud Sleeve
1967 - On
Tapered Sleeve
The Ball Stud sets inside a bronze-coated Bushing which slides inside the Sleeve. The Sleeve must be straight and round inside or the Bushing will bind or freeze inside the Sleeve. When this happens, the pieces which move the Spool no longer move and the valve doesn't work properly. For this reason the Bushing must slide smoothly back and forth inside the Sleeve area.
Most of the valves that come in for rebuild have the Ball Stud and Bushing binding or jammed somewhere in its travel, inside the Sleeve. Usually the tube of the Sleeve has been dented and is no longer round inside. Sometimes this is caused by an accident or road debris, but the overwhelming cause is improper removal. Many people (including professional mechanics) use what is generally known as a "pickle fork" to remove the Ball Stud from the Pitman Arm. NEVER use a "pickle fork" to remove anything that you ever intend to reuse.If you use a "pickle fork" to pull the Ball Stud out of the Pitman Arm, I QUARANTEE that you will damage the Sleeve. Use a proper tool to remove the Ball Stud or leave it in the Pitman Arm. You do not have to remove the Ball Stud from the Pitman Arm to disassemble the control valve. Once out of the car, it is far easier to to replace the Ball Stud on the bench.
More commonly on the integral-style Centerlinks, the Sleeve will be bowed and curved, causing the Bushing to lock up or bind.
The Sleeve area must be round and straight and the Bushing must slide freely inside or the control valve will not actuate properly. If the Sleeve is out-of-round, it must be repaired until the Bushing slides freely. Some rebuilders grind on the inside of the Sleeve or bore them out until the Sleeve is round again.  This method removes metal from the Sleeve, making it thin and weak. Some will even grind off the fresh bearing bronze on the Bushing until it is small enough to fit inside the damaged Sleeve. The proper way is to restore the roundness and shape of the Sleeve without removing metal. The integral-style Centerlinks that are bowed and bent must be specially straightened. This is difficult because these style Centerlinks are much harder steel than the removable-style Sleeves. The integral-style Centerlinks are also much more expensive and difficult to find, making repair more desirable.
While the items listed above are the most important and common areas of concern, there are many other parts inside a typical Control Valve/Ball Stud assembly that are often rusted, damaged or just plain missing. Some items are easily replaced, such as washers and bolts, but several are unique to a control valve. These miscellaneous parts come in no rebuild kit.
Some rebuilders will replace all the rubber parts but reuse many of the wearable hard parts in the Control Valve/Ball Stud assembly in order to cut costs. At least one will grind bronze bearing material off of an old ball stud bushing to make it fit an out-of-round sleeve tube. It is easier to repair the sleeve than grind the bushing, but they save a couple of dollars this way.
The parts shaded in blue, in the diagram to the right, shows those parts that are not part of any rebuild kit.
Unfortunately, they are often worn or damaged along with the usual parts.
Very often the bolts, nuts and washers used in the unit are stripped or damaged. The ball stud sleeve is often out-of-round and rusted internally. The tube hose seats are always grooved and damaged from use and over tightening.
This picture shows an exploded view of a typical Control Valve & Ball Stud Assembly. All of those items shaded in blue are usually included in a standard complete rebuild kit.. This consists of all the gaskets, seals and o'rings that would normally be replaced, but also several hard parts such as the Ball Stud & Seats, Ball Stud Bushing, Ball Stud Bumper & Spring, and Ball Stud Boot & Clamp.
Includes 1967 and later
tapered style
Ball Stud Sleeve
Control Valve/Ball Stud exploded view
The condition of the parts you will rebuild (or the core you will be sending in) depends alot on how you remove the Control Valve from the car and how you disassemble it. In most cases, standard tools will do a fine job. Removing the tie rod ends from the Centerlink, the Ball Stud from the Pitman Arm and removing the Pitman Arm from the Steering Box all require special tools that can often be rented from your local auto parts store.
Even if you are intending to replace items such as the tie rod ends with new pieces,
do not use a "pickle-fork" to remove them. You may not care that the tie rods are damaged since you will be replacing them, but the fork will also gouge the Centerlink and damage it.
You can probably rebuild your Control Valve/Ball Stud assembly if the reuseable parts are in perfect condition, they are removed and disassembled properly, and you have all the neccesary parts and instructions to do the job thoroughly.

But if the Spool Valve is pitted or scratched, the Centering Spring is pitted/rusted or collapsed, the Tube Hose Seats are grooved and distorted, the Ball Stud Sleeve or Centerlink is bent/damaged or out-of-round, any of 24 other internal parts are damaged enough to need replacement, you damage the unit removing it from the car, or any number of other unusual and odd things that are not covered in this article --- it would be cheaper, and better off in the long run, to let a professional rebuild your control valve.
For knowledgeable and professional rebuilding of Control Valves and other power steering components, go to REBUILDING SERVICES for more information
Remember that the removable-style Ball Stud Sleeve is located on the Centerlink by a small roll-pin located under the clamp. Unscrewing the control valve assembly from the Centerlink without removing this pin is possible (if you have a big enough pipe wrench) but it will tear up the threads on the end of the Sleeve and the Centerlink.
Do not take a "half-ass" approach to removing and disassembling the Control Valve assembly. Get the correct tools and do it properly.
Oh, did I mention - do not use a "pickle fork"?
If you are in the middle of a rebuild, or are thinking of doing one on your own, we will be glad to help you as best we can. Because we are busy rebuilding during the day, we cannot always help you by phone. But if you send us an email with a description of your problem, we will try and get back to you within 24 hours.
No Pickleforks Allowed !
In Summary ...