Electronic Power Steering - The Path Of Least Resistance

From the January, 2012 issue of Street Rodder

By Carroll Hamilton

Electronic power steering; no pumps, hoses, fluids, or leaks

Your hydraulic power steering system can drain as much as 5-8 hp from your engine and cost you somewhere between 1-3 mpg of fuel. A hydraulic power steering unit consumes more energy than your car’s air conditioner. Only wind resistance and road friction consume more energy.

While we Street Rodders do care about fuel mileage, the horsepower loss may or may not be of concern, given most street rods are overpowered.

Invented by Francis W. Davis and George Jessup in the ’20s, hydraulic power steering made its first commercial debut in 1951. Large vehicles were in demand and steering those boats could be a real workout. The hydraulic power steering solution was based on torque assist being applied to the steering box based on the amount of force applied to the steering wheel. Since the hydraulic pump was directly connected to the engine, energy was consumed even when no steering assist was being requested. The system worked, but it was far from efficient.

In 1993, Honda introduced the first “all electric” power steering (EPS) system on its Acura NSX. The system utilized a brushed DC electric motor and an electronic power control module. Since that time, manufacturers of EPS units have utilized switched reluctance (SR) motors, and brushless permanent magnet (BPM) motors all with new levels of efficiency. All of the major automobile manufacturers are introducing EPS in more models each year. The bottom line is hydraulic power steering units are old technology and eventually will be replaced. An EPS unit increases fuel mileage and horsepower, eliminates the big ugly hydraulic pump, the belt, the leaky hydraulic hoses, and the need for power steering fluid.

Unisteer Performance Products, designers and manufacturers of aftermarket rack-and-pinion steering assemblies for street rods and muscle cars, recently introduced Electra-Steer. The column drive Electra-Steer utilizes the newest technology being used by the major automotive manufactures to replace hydraulic power steering and Electra-Steer EPS is now available for street rods and any vehicle weighing 2,800 pounds or less.

These units consist of an EPS drive module, featuring a BPM motor and a dedicated EPS control module that utilizes state-of-the-art electronics. Available as an EPS retrofit unit that can be installed in your existing 1-7/8-inch ID or larger steering column (if the steering column is smaller than 1-7/8-inch ID it can be expanded at your local muffler shop to fit the 1-7/8 OD collars on the Electra-Steer unit). Unisteer Performance also offers a complete EPS column based on an ididit steering column; either way, the result is a significant reduction of manual steering effort.

OEM EPS units sense steering wheel torque, wheel speed, traction control input, location of the steering wheel, and other factors delivered from an onboard computer or Engine Control Unit (ECU). Both OEM and some aftermarket EPS units require software, programming, etc. Since most street rods do not utilize an onboard computer, the engineers at Unisteer Performance Products simplified the EPS control module to operate on steering input force (torque). Input from a steering torque sensor mounted in the EPS drive module is fed to the EPS control module. The EPS control module then commands the motor to provide appropriate assist based on the steering input force. In other words, the less steering input force the less assist is required, like at higher speeds.

As a retrofit kit or a complete steering column, the unit is fast and fairly easy to install. Everything is included, and Electra-Steer connects to your 12V power source.

In addition to the EPS drive module and the EPS control module, the kit includes a wiring harness, a fuse holder, complete instructions, and an LED light that is used as a code reader should the unit malfunction.

On the retrofit kit you must specify the ID of your steering column (1-7/8 minimum) and the input and output steering shaft connectors desired. Three-quarter Double D and three-quarter round weld on are the connector options. The retrofit unit is available as a plain unpolished or unplated unit or the fully polished or chrome-plated unit that we selected.

If a sensor or other component in the EPS system fails, the self diagnostics will detect the fault, set a code, and disable the power assist. A warning light will illuminate to alert the driver, and the driver will notice an increase in steering effort when turning the vehicle. The vehicle will still be safe to drive; actually the steering will be as it was before the Electra-Steer unit was installed. In addition, as a safety feature, the Electra-Steer unit is designed to “shut down” if it becomes overheated, reverting to the vehicle’s original steering capabilities. The chances of the unit overheating are very slim; Unisteer Performance Products had to spend 45 minutes doing figure-eight turns to develop enough heat to force the unit to shut down.

We selected a retrofit kit to install in our Speedway Motors Hot Rod steering column. The EPS module requires 8 inches of radial clearance from the steering column center. Once we determined the optimum location of the EPS unit, we removed 5-3/8 inches from our steering column in that area. We then removed 8 inches from the steering shaft in the same area. Remember “measure twice, cut once.”

Before reassembling we had flats machined on each side of each end of the cut steering shaft to form the Double D, which would slip into our Double D connectors on the EPS unit. Speedway Motors can supply Double D shafts in any length if machining is out of the picture. We could have selected the weld-on connectors, but in the steering system we personally feel more comfortable with mechanical connections, such as Double D and splined connections. If you chose weld-on connectors, and are not a certified welder, find one, for your safety as well as your fellow motorist; this is your steering.

With the shafts mounted in each end of the EPS unit, we drilled three equally spaced holes in the ends of the steering column sections that would connect to the steering unit. The steering column sections (upper and lower) were then installed on the EPS unit.

The completed steering column was reinstalled, the wiring was run, and the EPS module was connected per the instructions, and we were in business.

If you are in the process of building your street rod, or if you do not have power steering in your existing street rod, the Electra-Steer unit is your ticket to a fast and easy way to add power steering to your ride. If you have hydraulic power steering, Electra-Steer is the answer to eliminating the hydraulic pump, hydraulic hoses, drive belts, power steering fluid, etc.

Our ’32 Ford highboy was fairly easy to steer with the non-power steering Unisteer Performance Products rack steering previously installed. Now, with Electra-Steer, it is far easier to turn the wheels when sitting still—making us look cool when we palm our steering wheel when backing into our parking spot at the local cruise in.