Suspension : It’s All About Control
How shocks and struts affect tire wear, and winter driving safety.
Consumers tend to think shocks, struts, and springs are primarily designed for ride comfort, when in fact their vehicle’s suspension is an integral part of the vehicle’s safety systems, especially when it comes to braking and crash avoidance. Worn suspension components can reduce the stability of the vehicle and impact braking distance, while accelerating wear in other suspension components, including tires.
“Ride control issues have been amplified this year with the condition our roads are in, and as a result, people are becoming much more aware of the road conditions and the importance of ride control,” says Sean Cooney-Mann, Store Manager, OK Tire, Shorncliffe Road, Etobicoke, Ontario. “They are paying enough attention that they see a change in the drivability of their vehicles. When they hit a pothole, or some other type of impact occurs, they see a dramatic change in their vehicle’s ride and handling.”
One of the essential functions of shocks and struts is to filter out NVH (noise, vibration, harshness) transmitted from the road and through the wheels/tires and suspension. Modern ride control units have low-frequency and high-frequency damping characteristics that filter out this harshness before it reaches the cabin.
Given the increased popularity of low-profile tire/wheel packages, as well as today’s generally lighter-weight suspension systems, this function has become increasingly important. That’s why it’s so important to replace units with a technology that’s been engineered specifically for that application. If a vehicle is known to transmit more road noise, a leading ride control manufacturer may address this challenge through their internal valve settings for that application.
Inspection is critical
“Recommending and completing ride control service isn’t nearly as complicated as our industry makes it out to be.” advises Denise Hanefeld, Manager, Marketing Communications, North America Aftermarket, Tenneco. “If the vehicle is brought in for virtually any other service—new tires or brakes, alignment, even a drivability repair—it makes sense to use this opportunity to assess the vehicle’s overall condition, including the condition of safety-critical components like shocks and struts.”
Once the inspection is completed, the service writer or technician should let the customer know about other potential problems, including the presence of worn ride control components.
Advanced Driver Assistance Systems
Advanced driver assistance systems (ADAS) in newer vehicles are helping to amplify changes in ride control. “Many vehicles now have lane departure sensors, cruise control, etc., and these now play a crucial role in ride control because ride height has to be maintained,” explains Cooney-Mann. “If the struts, shocks or tires are not up to par, the car will nosedive, and the ride height will be compromised so that these variables can cause a dramatic change in the performance of the vehicle.”
Shocks and struts control spring movements which in turn controls tire movements and body stability. “Under-maintained ride control—worn shocks and struts—will cause the body to pitch forward during a hard stop,” explains Mac McGovern, Director of Marketing & Training, KYB Americas Corp. “That takes the load off the rear tires and forces the front brakes to do most of the work.
“Worn shocks and struts also cause variations in the tire to road contact patch, and that doesn’t leave electronic stability control systems (ESC) with much to control. If the tires can’t grip, then ESC can’t either. And when ESC can’t control the tires, then it can’t control the vehicle, and the driver has less chance of avoiding a problem.”