What is Base Valve Technology?
A base valve is essentially a static valve assembly built into the body of a shock between the working piston and divider piston. The addition of this technology allows racers to run ultra-low gas pressure for increased grip and tire life.
What are the Benefits of Running Ultra-low Gas Pressure?
Gas pressure is an important addition to performance shock absorbers; it keeps the nitrogen gas in-solution with the shock oil. Without gas pressure the shock oil will begin to foam as the air comes out of solution with the oil. This foamy amalgam has a much lower viscosity than the standard oil – negatively impacting the damping characteristics of the shock, translating into reduced effectiveness and fade.
Excessive gas pressure can have its own negative impact on damping performance. Gas pressure in the chamber separated by the divider piston creates resistance on the column of oil in the shock body. As a damper is compressed the shaft must displace the oil in the closed system, this creates a phenomenon called gas reactive pressure or rod pressure, whereby the shock will try to re-extend itself.
Gas pressure directly translates into increased rod pressure, and rod pressure creates additional spring rate, beyond the planned K-rate of the coil (or other) spring.
By running low gas pressure, less rod pressure is generated and therefore less external spring force is introduced into your suspension equation.
It is commonly understood that the bigger the surface area of the working valve (piston and shim stack), the greater resolution or control you have over the tuning of your damper. By running BILSTEIN base valve technology, you have two independent yet perfectly balanced metering valves to control the flow of oil through piston orifices. This design effectively doubles the piston surface area for increased control and less threat of inducing cavitation at high shaft speeds with a single working piston.
The choice to employ base valve technology should ultimately be a matter of driver preference. The tactile interface a driver shares with their racecar is very personal and setup varies due to individual taste. Base valve shocks are distinguished by giving a more direct translation or feel of what is happening at the contact patch of the tire. Slick racetracks and challenging surface conditions respond to different shock configurations. If you’re unsure as to whether or not a base valve setup is beneficial for your race program, contact a BILSTEIN Motorsports representative for more information.