Article and photos by Chris Petris
Power steering is a mechanical wonder that many of us often take for granted. For some, it is hard to even remember a time without power steering. Today’s systems are cost effective to manufacture and are very reliable with just basic maintenance. It is likely that these systems will remain in place for several more years despite the pressure to continually increase fuel economy.
The power steering system consists of a reservoir, pump, relief valve, control valve, power cylinder, and high/low pressure hoses. The system is effective because of the pressure differential that is created by the power steering pump. A quick explanation of how power steering works is in order. The reservoir supplies the fluid to the pump, which is driven by the engine via belt. The fluid is pressurized and sent to the control valve and the relief valve. When the steering shaft is turned, the control valve sends fluid to the power cylinder and the power cylinder uses a piston to aid in reducing steering effort.
General Motors did not intend to give the Corvette effortless, Cadillac-like steering. Instead, they opted to design the system to provide steering assistance while offering good feedback and response on the road at speed. While you cannot expect to turn your Corvette in a parking lot with just your fingertips, the steering assist system is a vast improvement over not having power steering at all.
The power steering assist system does have an Achilles heel, however. The hydraulic cylinder shaft seals are subjected to sand, debris, and all of the elements which wear them down and inflict damage. In addition, control valves can wear and, with their multiple fluid connections, leaks are inevitable. Many control valves are replaced due to what appears to be excess play in the ball stud. In order to make a proper diagnosis, however, the engine must be running with fluid pressure. When the engine is running, the ball stud play should subside. If not, control valve replacement is necessary.
Many times the control valve is also blamed for excess steering play when indeed the steering coupler is worn. Steering couplers are comprised of a rubber disc sandwiched between two metal flanges. The steering couplers job is to eliminate steering wheel vibration. Over time, the rubber deteriorates and causes excess play in the steering wheel. The steering coupler has two pins as a safety precaution to prevent a total loss of steering.
As a result, a cottage industry has formed because of the number of control valves and cylinders in need of replacement. The same items appear on several Corvette generations, making it beneficial to the manufacturers. When it comes time to renovate your power steering system, you have plenty of options. New and remanufactured components are available, as well as hose kits. Unless you are aware of the replacement history of both the power steering cylinder and control valve, it is best to replace both including all of the hoses. The photos that follow will guide you through the process.
This oil soaked, well-worn steering coupler off of a 1969 Corvette created excess play. The best way to check this coupler is to have someone turn the steering wheel within the free play range. Watch for movement in the coupler that does not transmit to the lower flange.
What a difference this correct Corvette Central complete lower flange and coupler assembly (part # 563135) makes. There are rubber disc replacement kits available that can save you some money, but require quite a bit of work to install. Keep in mind that the majority of these vehicles are 40+ years old and the metal flanges do wear, so it is a good idea to replace the entire assembly.
Apply anti-seize to the drag link threads to ease installation and future removal of the power steering control valve.
During the installation of the power steering control valve, it is critical to ensure that the control valve screws on at least 3 or 4 turns with light effort at first. After 3 or 4 turns it will require more effort to seat the valve. Use a ¾“ box end wrench placed on the ball stud to tighten.
The castellated nut is tightened, with an additional half turn until the cotter pin hole is lined up.
In order to ensure your comfort and minimize the risk of inadvertent injury, the cotter pin ends should be bent over and pressed down.
Make sure that you have the machined spot in the drag link lined up with the control valve bolt hole, then install the grade 8 bolt and torque it to 45 ft. lbs.
Install the hydraulic cylinder using the same method as the castellated nut on the power steering control valve to tighten it.
At the frame side of the hydraulic cylinder we install a large washer, rubber bushing, and sleeve. Make sure that the sleeve is installed. The sleeve is often omitted, resulting in crushed rubber bushings.
This is the correct installation of the washers, bushings, and castellated nut. The castellated nut is turned down until the washers contact the sleeve, and then an additional quarter turn is applied to line up the cotter pin hole.
We find that it is easier to install the hose at the power steering pump before the power steering pump control valve.
Again, it is easiest to install the power steering pressure hose onto the control valve next. We are using a wide fitting wrench to prevent line nut damage.
Using a fitting wrench, the power steering return hose can be installed now.
The hoses can be tricky to install on the power steering cylinder since they angle outward and slightly upward. Do not use a wrench to tighten these until you start them by hand and secure them with at least 3-4 turns manually.
The cylinder to control valve hose is installed at the control valve. These hoses must crisscross each other or your power steering will be non-existent.
After the installation has been completed add chassis grease, if required, using a grease gun and a maximum of 3 pumps. Check with your control valve supplier to verify whether or not greasing is necessary.
The small screwdriver indicates a possible friction point where the control valve hoses will hit the cylinder mount. Before starting the engine, move the wheels right to left and left to right throughout the full range of travel watching the hoses for any possible friction or binding points. Be sure to look at the power steering pressure and return hoses for binding concerns as well.
Upon initial start-up, do not place your arm between the steering wheel spokes. A maladjusted control valve can cause the steering wheel to turn abruptly left or right on its own. We are removing the cap to gain access to the control valve balance adjustment 7/16” nut. This particular 1964 coupe exhibited a pull to the right. Before implicating the control valve, we attempt to adjust the balance.
We place our ¼” ratchet with 7/16” socket on the balance nut; then the engine is started. We adjust the balance nut clockwise until the steering wheel begins to move slightly and then rotate the nut counterclockwise until the steering wheel turns in the opposite direction. This will give us the approximate number of turns required to allow the steering wheel to rotate in both directions. For example, if two clockwise turns were required then one counterclockwise turn would center the valve.
If you would like to enjoy the benefits of power steering on your 1963-1979 Corvette that was not factory equipped with power steering, Corvette Central has kits available to make the conversion.
- Be prepared; this is a messy job with multiple lines containing fluid to detach and reattach.
- When you have the hoses disconnected, do not move the wheels or a shower of power steering fluid will ensue.
- Refill the reservoir with power steering fluid as opposed to automatic transmission fluid which is sometimes used. Power steering fluid is specially designed to offer higher heat resistance.
- Power steering systems have a return that constantly shuttles fluid back to the reservoir making bleeding the system unnecessary.
- When first started do not overfill the system. Watch carefully because once the engine is running the fluid level will drop. Rotate the steering wheel back and forth 3-4 times with the engine running. Shut off the engine, open the power steering reservoir fill cap, and allow the air to escape the fluid. After 10 minutes, check the fluid level again and if necessary add more fluid.
562330 ’63 – ’82 New Power Steering Cylinder $139.95
562336 ’63 – ’82 New Power Steering Control Valve $199.00
562355 ’63 – ’82 Rebuilt Power Steering Cylinder $99.95
562350 ’63 – ’82 Rebuilt Power Steering Control Valve $99.00
562209 Redline Power Steering Fluid (Quart) $11.95
Corvette Central has a variety of hose kits and complete kits with hoses, valves, cylinders, in your preferred configuration of new/remanufactured components.