Bilstein Shock Cover - The Big Cover-Up - Tech

There is a simple remedy to this situation but it's highly compromised: Tuners reduce their resistance. In other words, they intentionally make the damper less effective to prevent it from self destructing or just making you uncomfortable. "It will make a car ride soft over rough stuff, but at the cost of vehicle response," Duck said. In a nutshell, loose dampers make the car feel lazy.

De Man, De Legend, De Carbon
Most conventional dampers consist of a tube within a tube. The outer tube is in fact an oil reservoir and not the cylinder itself. Within that body is another tube called the working cylinder, which in most cases is a piece of thin sheetmetal bent into a tube and welded. "It's referred to as a twin-tube design," Duck said. "It dramatically limits piston diameter and valve options. In fact, some twin-tube pistons are so small that the manufacturers relocate the valving to the end of the cylinder," he noted.

But an engineer named Christian Bourcier De Carbon designed a damper whose body doubles as the working cylinder. "We refer to it as a monotube, or single tube," Duck said.

Though the monotube design more efficiently sheds heat-which is good-its real asset is its greater piston area. "The monotube piston offers so much more valve area than a twin-tube ever could," he revealed. In fact, the piston head doubles as the valve network in the De Carbon design.

Intake ports on each side of the piston head channel fluid through the piston. Small discs that shroud most of the port outlets turn these ports into bleeds.

Now here's where a damper like a Bilstein runs away and hides from a conventional damper. "Those discs are actually springs," Duck said. Once the piston velocity exceeds the bleed capacity, the discs deflect to let the ports flow a greater amount. "We call it deflective-disc valving," he added.

Remember how we said a bleed-only type damper has a progressive rate? Well this deflective-disc design translates to a digressive rate, or a rate that increases more proportionally with velocity. The damper does get stiffer when necessary on rougher roads and during great wheel impacts, but not stiff enough to generate excessive heat or lock up.

This digressive rate gives dampers a sort of Jekyll-and-Hyde personality: "We can make a car feel tight and responsive without the risk of overheating or locking up the shocks at higher speeds," Duck maintained. "That sort of control prevents body roll and lets the tire follow the road," he said, adding, "and that translates to a better ride and improved traction across the board." It's for this broad operating range that the monotube damper has been the mainstay in the racing world-especially in the off-road industry-for the past 40 years. In fact, RCD Classic's parent company, Race Car Dynamics Suspension, is a leader in that field.

These principles apply independently to the compression and extension stroke alike. True, the garden-variety twin-tube damper's compression rate differs from its rebound rate, however, it generally relies on a number of small-ball check valves and very thin and delicate springs that ultimately wear out.

Like everything, a Bilstein does have a finite lifespan, however, "A Bilstein lasts several times longer than a conventional shock," Duck maintained. But that's no reason to discard a Bilstein. "We can rebuild them or re-tune them for changes to the car at any time," he added.

Sounds pretty high-tech, doesn't it? Maybe the latest whizbang technology that trickled down from the super-car sector, right? Manufacturers like Porsche, BMW, Audi, Bugatti, Ferrari, Lamborghini, and Jaguar do employ Bilstein dampers. De Carbon patented his monotube design all the way back in 1953. Bilstein bought the rights to use the design soon after, and since 1957 select Mercedes-Benz platforms have worn Bilstein dampers exclusively.