Improve Steering Feel with a Tuneable Power Steering Pump

KRC's Pro Series hydraulic power steering pump is unique in that it can actually be tuned to provide the steering response that actually gives you the best "feel" from the driver's seat.

KRC’s Pro Series hydraulic power steering pump is unique in that it can actually be tuned to provide the steering response that actually gives you the best “feel” from the driver’s seat.

It isn’t widely known that you can improve your feel for what you car is doing on the race track by tuning your power steering pump, but it is something that’s possible and many of the more savvy racers do it regularly.

Optimizing feel to the racer’s steering is a bewildering task for most of us. But KRC Power Steering has made it easy by introducing a range of replaceable flow control valves for their hydraulic steering pumps.

The flow control valves work similarly to jets in a carburetor. There are nine of them in varying sizes, and they can vary power steering fluid flow from four to 12 liters per minute, which is approximately one to three gallons. The largest orifice provides maximum steering assistance while the smallest provides maximum steering feel.

Though the standard KRC pump flows 8 liters per minute, by using flow control valves with larger orifices, those marked B, C, D, or E, the flow rate can be increased to 12 liters per minute (3.17gals) in one-liter increments. The higher letter indicates greater hydraulic assistance, but you get less feel through the steering wheel. In contrast, flow valves marked with numbers 4, 5, 6, and 7 provide less assistance; the lower the number, the greater the feel but the less assistance.

Momentary loss of power or “pump catch”

Although the differences in the orifice size of each flow control valve are incredibly small, moving up just one size increases power steering fluid flow though the pump by one liter a minute.

Although the differences in the orifice size of each flow control valve are incredibly small, moving up just one size increases power steering fluid flow though the pump by one liter a minute.

“From an engineering perspective it was such a tricky thing to get right,” says Roper. “The critical orifice is created in the -6 flow control valves and each valve is drilled undersize and then brought to the exact size by reaming. The difference in diameter between each orifice is a mere two-tenths of one millimeter (0.007 in), and each orifice is held to a tolerance of 0.0002 inch.” Such precision is necessary because while the steps between each flow control valve are just two-tenths of one millimeter (0.007 in), each one increases the flow rate by one liter of fluid per minute. Without maintaining these strict tolerances the technology won’t work. In fact, it was when KRC first experimented with tighter tolerances throughout the pump’s design that they discovered its fuller potential.

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By changing the orifice in this blue fitting you alter the feel and weight of the steering. The larger orifice provides maximum steering assistance while the smaller provides maximum steering feel. If it’s too heavy, increase the orifice diameter; if too light reduce it.

To the best of Roper’s knowledge the KRC pump is the only one that can be tuned this way for steering feel. “For years, most of our competitors have just modified OEM production power steering pumps,” he explains. But OEM pumps, by necessity, have relaxed tolerances to accommodate mass production and cost requirements. In contrast, KRC’s Flow Control Technology uses exacting tolerances that are impractical in the OEM environment. “Although several of our competitors have tried over the past 16 years to duplicate this process,” adds Roper, “it cannot be duplicated in mass-produced OEM pumps—that’s the difference between a $200 production pump and a $600 proper racing unit. Wide tolerances cause excessive internal leakage that makes it impossible to regulate the output flow of the OEM-style pump.”

Source
KRC Power Steering
(770) 422-5135
www.krcpower.com
 

About the author

Jeff Huneycutt

Jeff Huneycutt has been in the automotive industry long enough to collect more project cars than he can afford to keep running. When not chasing electrical gremlins in his '78 Camaro, he can usually be found planning unrealistic engine builds.
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