CDC Shocks and Struts (VIDEO)

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What if I told you that there was technology that could prevent wheels from falling into potholes, reduce stopping distances, and offer drivers a new level of comfort and control, you might think this was the technology of the future. But the reality is that some cars and trucks have been equipped with this technology for more than 20 years. The technology is called Continuous Dampening Control, or CDC for short.

These units use electronically controlled valves that are adjusted in milliseconds to control compression and rebound dampers. For example, the unit can increase bounce when a pothole is detected by a wheel displacement sensor or camera. This prevents the wheel from falling into the hole and hitting the back of the hole. For braking, the CDC dampers can increase compression at the front and increase bounce at the rear to prevent nosedives

The heart of the system is a valve located on the piston or base of the shock absorber. Inside is an electromagnetically controlled valve that controls the size of the valve opening. Aperture size is calculated by modules connected to sensors and other systems on the vehicle.

The primary sensor for the CDC is the wheel displacement or position sensor. This is not a vehicle height sensor. Instead, these sensors continuously measure the position of the suspension relative to the road and body. The CDC control module will also use data from the ABS, stability control module and the electric power steering for more information about vehicle dynamics.

CDC shocks and struts use conventional mono-tube and twin-tube oil-filled dampers. The rod, gas chamber and piston are of the same construction as the passive unit. Just like passive units, they can be damaged internally and externally. Also, they can wear out like passive units.

When inspecting a CDC unit, the same rules apply as for a conventional unit. Look for leaks on the surfaces, especially around the shaft seals. Check the condition of the boot and bumper. Check shaft condition for signs of impact and corrosion.

The knee test in the bumper is not a valid test for CDC units. Because valves vary depending on vehicle speed and dynamics, a static test in your bay may yield inconsistent results. A test drive under controlled conditions is the best tool for assessing system health.

For CDC diagnostics, a scan tool is required. Just like engines, CDC systems have diagnostic trouble codes. When the vehicle is first started, the CDC system will perform a self-diagnosis. If there is a problem with the actuator or the CDC module is not communicating with other modules, a diagnostic fault code will be assigned.

For CDC replacement, it is recommended to replace the CDC units in pairs. You may be tempted to replace the CDC unit with a conventional passive unit listed in the catalog for the same model. This will disable the CDC system and endanger the safety of the vehicle. Also, spring rates for CDC and passive units are different and can cause handling and ride quality issues.

CDC shocks and struts are a huge opportunity for stores. Replacement units can restore your car or truck to its full capabilities for safety and convenience.

This video is sponsored by Sachs.