Electronically Controlled Dampers

A conventional shock absorber or strut has fixed damping — it provides the same resistance to compression and rebound regardless of road conditions, speed, or driving style. It is a compromise: soft enough for comfort, firm enough for control. Electronically controlled dampers eliminate that compromise by adjusting their firmness in real time — as fast as every millisecond — based on what the vehicle needs at that exact moment.

MagneRide is the most well-known adaptive damper technology. The shock absorber is filled with a special fluid containing microscopic iron particles. An electromagnet coil wraps around the piston inside the shock. When no current flows, the iron particles float freely and the fluid is thin — the damper is soft. When current flows through the coil, it creates a magnetic field that causes the iron particles to align and form chains — the fluid thickens instantly and the damper stiffens. The ECM can adjust the current (and therefore the stiffness) in about 5 milliseconds — faster than you can blink.

Other manufacturers use electronically controlled solenoid valves built into the damper piston. The ECM commands the solenoid to open or restrict oil flow through the piston, changing the damping force. BMW's Adaptive M Suspension (EDC — Electronic Damper Control) works this way. Mercedes uses solenoid-controlled dampers in their AIRMATIC system. These are slightly slower to respond than MagneRide but less expensive to manufacture.

GM uses MagneRide on the Corvette (all C7 and C8), Camaro, CT4-V, CT5-V, and Escalade. Ford uses MagneRide on some Mustang models and previously on some F-150 Raptors. Audi uses MagneRide on RS models. BWI Group (formerly Delphi) supplies MagneRide to all of these. BMW uses EDC on most M cars and as an option on standard models. Mercedes uses electronically controlled dampers on most models. Hyundai uses them on Genesis vehicles.

Adaptive dampers are generally reliable, but when they fail, the damper defaults to its firmest or softest setting depending on the design. A blown MagneRide strut typically leaks the magnetorheological fluid — you will see a dark brown or black oily residue on the strut body. These are significantly more expensive than standard struts — $500 to $1,500 per corner just for the part. The ECM monitors each damper's response and will set DTCs if a damper is not responding to commands. Wheel speed sensors, body accelerometers, and steering angle sensors all feed the damper control module, so a problem in any of those sensors can cause the adaptive dampers to behave incorrectly.