PHOENIX -- Most folks tend to deal with the greasy bits underneath their vehicles with apprehension. Someone tells them a part needs replacement, a part gets replaced. To the typical owner, that's all it is: a part.

The cagey execs and engineers who run Monroe Auto Equipment Co., a unit of Tenneco's Automotive Div., noticed that the aftermarket -- and to a large degree the automakers -- were taking a dim view of shock absorbers and struts, or "dampers" and "ride-control products," as Monroe prefers.

Ride-control products "had become a commodity," says Jack L. Thompson, the energetic president of Monroe. "Nothing much had changed since the '80s, when gas-charged products were introduced."

Now Monroe, world's largest producer of shocks and struts and maker of more than a quarter of a million of them daily, realized the market had to be conditioned to recognize ride-control products as more than a commodity if the company was to continue expanding.

To that end, Monroe has developed a new, position-sensitive damper -- PSD -- called Sensa-Trac. Technically, the SensaTrac damper is designed to provide improved ride and handing characteristics over common replacement dampers. From a business standpoint, Monroe wants Sensa-Trac to "realign" the aftermarket to accept superior (and, incidentally, pricier) alternatives to commodity-grade shocks and struts.

Sensa-Trac dampers are based on Monroe's longstanding gas-charged dampers, known as Gas-Matic. But intricately shaped grooves are added on the inside of the damper's pressure tube. In normal driving conditions, the shock fluid simply flows around the piston, which is contained in the pressure tube. If an aggressive maneuver or a large bump or pothole causes the piston to range further in its travel, the grooves are taken out of play and the shock fluid movement is restricted to only the valved area inside the piston, increasing the pressure of the fluid and the firmness of the ride.

By "sensing" the position of the piston, Sensa-Trac's shaped grooves act to progressively firm up the damping rate if the piston makes out-of-the-ordinary movement toward the upper and lower portions of its stroke.

Curiously, Monroe's first launch of Sensa-Trac was for sport/utility vehicles (SUVs). It's not surprising, however, when Sensa-Trac-equipped SUVs are tested alongside their OEM-damped counterparts at the Bob Bondurant School of High Performance Driving here. The Sensa-Trac controls a large degree of the bobbing and corkscrewing motions common to SUVs. And light-truck applications provide equally impressive ride characteristics.

And the Sensa-Trac dampers even impart a discernible upgrade in the ride and handling of European passenger cars, generally acknowledged as a group for above-average levels of damping control. For some of these upscale cars, most notably a Mercedes C-class, the Sensa-Trac enhanced handing is an almost shocking (pun intended) improvement over the production car's dynamic balance.

A few engineers quietly concede the company would like to see Sensa-Trac technology adopted for OEM fitment, but they admit it's likely only for applications where the OEM would not have to absorb the added $150-or-so per car cost.

I say good luck to Monroe if they can urge OEMs to specify better dampers because they're the sort of component cruelly bean-counted by almost every automaker, yet they contribute so much to a vehicle's dynamic balance -- and active safety. With sales in 91 countries, tech centers in Europe and Japan and joint ventures in many emerging markets, perhaps Monroe is positioned to make the often penny-wise, pound-foolish OEMs see the light regarding ride control products.