Bilstein currently offers more than 20 part numbers in six different designs, including standard shocks, chrome shocks, and coilovers-all in varying lengths. And since the company builds each of these rod shocks by hand at its Poway, California, facility, it can tailor and valve each one specifically for each application.
At Race Car Dynamics, Duck says, "We have the ability to go outside the normal valving guidelines to work with special applications. We work with people to find out what they want out of the shocks and make those changes. That's what we can get from offering a handbuilt shock." They also have a new line of Classic shocks, which are specifically tailored to the hot rod and kit car market. If you give Duck a call at RCD and answer some questions about how you'll be driving your car, he'll be able to recommend and build a shock with the correct valving for your vehicle.
Obviously, well-designed, high-quality products come at a price, but we were surprised at how Bilstein's pricing lined up with other quality shocks. Considering what Bilstein designs into its shocks and the willingness to cover its products with a lifetime warranty, you could look at the shocks as an investment. And with RCD's commitment to fine-tuning your vehicle's suspension needs, it turns out to be a win-win situation.
After a tour through the Bilstein facility and a brief rundown on what sets monotube shocks apart, we were informed why Porsche, Mercedes-Benz, GM trucks, and racers from Formula 1 to NASCAR run Bilstein shocks. If nothing else, it might give you something else to look at the next time you're out shock hunting: the inside.
Notice there are basically two pistons in a Bilstein: the lower one for damping (the working piston), and the upper one (the dividing piston) to separate the nitrogen gas from the oil. This illustrates how the dividing piston acts as a snubber. | 
Once the charge was removed (evidenced by the gas/oil piston's higher position), the working piston cavitated the oil. That's what leads to control loss, and it's the very thing that happens in non-gas-charged oil shocks and, to a lesser degree, in low-pressure gas shocks. Note how the piston rides directly on the outer wall. Bilstein attests that the exposed cylinder surface area sheds heat more efficiently than a twin-tube shock, thereby reducing the possibility of heat-induced aeration. | 
In the background, Gerry Dillard charges reservoir shocks for off-road race truck teams. The pegboard behind Dillard's finished shocks holds several hundred deflection discs of varying resistance that Dillard and the rest of the crew use to fine-tune its shocks to each application. |