Technical Info: Bilstein Shocks - Mono-Tube vs. Twin-Tube

There are two basic types of shock absorbers used in today's short track racing: the conventional twin-tube reservoir shocks and the mono-tube gas pressure shocks pioneered by Bilstein.

Most short track racers still race on the older style, twin-tube shocks. But if you watch closely, you'll find more of your competitors switching to the up-to-date, mono-tube gas pressure shock absorbers. Although there are other brands of mono-tube gas shocks making an appearance in America's pit areas, Bilstein technology is so far ahead and so different, that their performance cannot be equaled.

Bilstein's larger piston area produces instantaneous response to the slightest suspension movements. Dead spots in a Bilstein are an impossibility.

Deflective disc valving in Bilstein shocks eliminates the need for check valves and tiny coil springs that cause inconsistencies in shock valving. All Bilstein shocks of the same part number produce, with little variation, the same damping force. Twin-tube shocks cannot be built with as narrow a band of consistency. In other words, when you bolt on a Bilstein, you know what shock valving is in your car.

Shock absorber performance fades away when the oil in the shock cavitates (foams). Conventional twin-tube shocks that are called "gas charged" contain a small plastic bag holding a minuscule amount of gas under little pressure. This design, while low in cost to manufacture, is ineffective on the track.

Under extreme G-forces, on rough tracks and in high heat conditions, "gas charged" twin-tube shocks do not resist cavitation as effectively as mono-tube gas pressure shock absorbers. This is the reason that all Cup, Indy Car, Formula One and Off Road racers long ago discarded twin-tube shocks in favor of mono-tube gas pressure technology.