Shock valving can be confusing, now we’re not talking the difference between compression and rebound, we’re talking about the internal pieces that control the flow of oil and ultimately dictate the behavior of the damper.

Shim stacks that influence the flow of oil come in a variety of customizable and tailored configurations. To better understand the complexities of modern multi-adjustable shocks we stopped by the Öhlins booth here at PRI.

A few years back Öhlins introduced their Road and Track line of coilovers and we covered the basics of their operation. In a nutshell the Road and Track system employs a revolutionary valving system Öhlins refers to as Dual Flow Valve (DFV). This speed sensitive system allows for compliancy and comfort over rough or uneven surfaces, but responsiveness and support under cornering.

To accomplish this the shock oil is routed in a very particular way. Moving beyond the layman’s explanation in brochures we consulted Öhlins’ automotive manager Christer Lööw.

The main valve stack is responsible for high speed operation. That is when the vehicle encounters small imperfections or shocks due to uneven road surfaces. Running down through the center of the valve body is a needle and seat like in a carburetor that acts as a bleeder valve for low speed operation under cornering loads.

According to Lööw, “The Dual Flow Valve is like an extra piston with two stacks — compression and rebound that meters flow through the jet. At very low speed oil can flow through the very narrow passage at the bottom, at medium speeds it started to choke-off and open either the compression or rebound stacks depending on which direction the flow is coming.”

While visualizing the fluid dynamics of this operation may prove challenging, Öhlins’ cutaway helps. Reducing back down to simpler terms, as shock shaft speed increases and oil flow exceeds the capacities of a given orifice, additional paths prevent themselves in the form of valve stacks.

We hope to give Öhlins DFV technology a try in one of our project vehicles and see for ourselves how the performance transitions from surface to surface. With a background in racing from WRC to Moto GP and everything in between we’re pretty confident the Swedes know what they’re doing.