The Reason That Shock Absorbers Fail

  Due to the way shocks appear to be simple in design, I was wondering what it was that made them fail. There are likely many people who would like to know the answer as to why shock absorbers fail. With that in mind, it's a perfect opportunity to delve into shocks absorbers technology and explain how they  work and what causes shocks to fail.

  The folks at Bilstein Shock Absorbers explained the technology behind their shocks. Bilstein has become the leader in the development of automotive suspension technology by manufacturing monotube gas pressure shocks and struts, as opposed to the more conventional twin tube design used by most OE and aftermarket manufacturers.

  To understand what makes one shock absorber design superior to another, you first need to understand how and why they work. Teamed with a coil spring, the shock absorber is responsible for counteracting the spring's behavior and tendency to compress and expand as it encounters bumps. As the piston travels up and down inside the shock, the hydraulic oil passes through holes in the working piston, and any oil control valves. The resistance provided by the small holes in the working piston ultimately converts the energy exerted to compress the spring and the energy released as the spring expands into heat, and determines the shock absorber's overall resistance to motion.

  Found on most passenger vehicles, twin tube shocks are the most common design and generally are the least expensive. While adequate for most normal driving styles and conditions, twin tube shocks are noticeably limited when used in high performance driving situations or on rough roads or terrain. The reason for this is that an increased rate and frequency of piston travel will cause the hydraulic oil to overheat, which leads to foaming of the oil and the subsequent loss of shock absorber effectiveness.

   While heat is a byproduct of an effective shock absorber, heat build up will cause a shock to fail and is the most common cause of failure. To reduce the chances of shock failure, it's important that heat is able to dissipate from the oil and shock absorber housing, contributing to lower operating temperatures. However, because of the nature of the design of a twin tube shock, heat tends to build up and gets trapped inside the two tubes that make up the shock absorber, which leads to fade and eventual failure.