By
Counterman
Ride control is a broad term. It refers to anything that controls and affects the operation and reaction of the suspension to road conditions, including the springs, shocks and struts. For many years, changing the ride control aspects of a vehicle meant at minimum, physically changing the shock absorbers with units that had different internal valving.
This altered suspension performance to match what the vehicle owner was after, which was typically a modification to match the suspension with the use of the vehicle, for example off-road or racing. The biggest problem is you were stuck with the characteristics you ended up with until you switched back to the original components.
Then, in the 1990s, adjustable valve shocks and struts became popular. These systems had two or three comfort and sport settings that could be changed with buttons on the dash. These systems played the role of firming up the suspension if the driver wanted a sporty feel while driving.
But technology never slows down, and for years now, many auto manufacturers have been utilizing continuously variable dampening systems, referred to as continuous damping control (CDC) in their vehicles. There are many different names for this type of suspension depending on the vehicle manufacturer, but it’s often generalized as active suspension or active ride control.
These systems have evolved to the point where they utilize electronically controlled valving to actively change dampening characteristics in milliseconds to control the compression and rebound of a shock absorber or strut.
By utilizing this high level of control, there are many benefits over a traditional system including enhanced driving comfort, improved handling and cornering, precise tracking during acceleration and shorter braking distances, all of which adds up to improved safety.
To give you an example of just how precise these systems can be, they can increase rebound when a pothole is detected by either the suspension displacement sensors or a camera. This prevents the wheel from dropping down in the pothole and hitting the backside of the hole. For braking, a CDC dampener can increase compression in the front and increase rebound in the rear to prevent nosedive.
On old, electronically adjustable systems, there was typically a small stepper motor on top or on the side of the shock or strut that changed the size of the orifices in the piston or at the base. The compression and rebound were not independently adjustable.
Today, most new systems use coils and/or magnets to adjust rebound and compression in real time, which are sometimes called actuators or pulse motors. Most active ride control systems have their own module that might also control the air ride system, and most control each of the four dampening units individually. They need information to work like vehicle speed, steering angle and readings from the yaw and accelerometers, and they are often part of the stability control system.
When technicians are faced with diagnosing system problems, they have to look at the entire system, not just the dampeners, and scan tools are necessary for communication. While these types of shock absorbers and struts can leak like traditional units have in the past, diagnosing them requires specific knowledge and procedures related to the system being worked on.
For many years, a static test was an acceptable way to check shock absorbers. Performing one was as simple as bouncing the suspension and watching to see if the vehicle returned to ride height without any continued motion. This type of test isn’t valid on a vehicle with active suspension since the variable valving on these dampers is dependent on speed and vehicle dynamics. It’s best to follow manufacturer information and procedures to assess system condition.
One thing that hasn’t changed is shock or strut replacement. The process is virtually unchanged with the exception of disconnecting a wiring harness connector, and the age old rule still applies: replace these shocks or struts in pairs.
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By Counterman
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