Auto Service World
Feature   December 1, 2011   by Nestor Gula

Ride control conundrum

Neglecting shocks and struts affect more than ride comfort

The truth is that most drivers don’t notice any ride control issues until something catastrophic happens.
“Often people come in and complain that the brakes aren’t working properly,” said Mark Sach-Anderson, shop foreman at Doctor H Honda in Etobicoke, Ontario. “It turns out that the brakes are fine – it is the bad transfer of weight by the shock absorbers that is causing braking problems.”
He said that drivers ignore their ride control systems for various reasons. One part is price but “the big reason is that they do not know what a shock can do for them. Unless it’s making noise and banging around, or bouncing around, nothing is done.” Convincing a client is not easy but must be done he said. “When you sit down and explain to them that a shock is not just there for comfort. It makes a difference on braking and handling and over all stability.”
“Shocks and struts play an integral role in your vehicle’s suspension system,” said Thomas Wittman, the Answerman technician, with Gabriel. “They are designed primarily to give you a much smoother ride by absorbing and damping feedback from the road. One of their most important functions is to influence the control and handling characteristics of your vehicle. They work to keep your tires on the road and to keep you safe and comfortable.
“Without them, a vehicle would continually bounce up and down, making handling and steering of the vehicle extremely difficult, as well as dangerous. Vehicle ride control, safety, and a driver’s ability to steer and brake depend on having firm contact between the vehicle’s tires and the road. Shocks and struts aid in ensuring this contact remains secure under any driving condition.”
By keeping four tires squarely on the road the car will always be able to be controlled by the driver especially when emergency manoeuvres are required. “Shocks and struts also help control vehicle weight transfer in many situations, such as sudden stops, when taking evasive action at high speed and completing tight turns,” said Bill Dennie, director, ride control channel management, North American Aftermarket, Tenneco. “Without properly functioning ride control units, the weight of the vehicle will almost instantly shift from back to front or side to side, which can affect stopping performance, steering precision and overall stability. Finally, shocks and struts can affect tire wear and the longevity of other chassis components. Signs of abnormal tread wear patterns or accelerated tire wear can often be directly related to worn ride control units.”
Brake performance and stopping distances are degraded when a vehicle’s shocks are worn or have failed. “The presence of one 50 per cent degraded shock or strut on a vehicle can increase braking distances by more than three meters in some situations,” said Dennie. “Worn shocks and struts can be dangerous and can significantly increase stopping distance by 12.3 feet or 11.7 per cent when stopping from 50 mph, and by 22.6 feet or 11.2 per cent when stopping from 70 mph,” echoed Gabriel’s Wittman.
Like Sach-Anderson said, most drivers and service stations don’t service the ride control system until something breaks and there is noise coming from under the car. Shocks and struts are moving parts and moving parts deteriorate with use.
“Shocks and struts will rarely fail completely but they do wear out,” said Wittman. “That wear and tear is a gradual process that happens over time. A shock can be composed of up to 40 precision engineered parts, which include valves, valve seats and springs, pistons, a piston rod and a number of high precision parts and seals. All of these components are susceptible to wear and tear over time. That’s why Gabriel recommends that you have your shocks checked by a qualified service technician every 12 months or 12,000 miles.”
Tenneco’s Dennie said, “Typical shocks and struts “stroke” an average of 2,815 cycles per kilometre – that’s nearly 34 million cycles for every 12,000 kilometres, so they see a lot of use and abuse. They are susceptible to additional wear cause by heavier usage patterns and severe road and environmental conditions; so each vehicle and driver might see a different rate of wear.
What’s important to remember, though, is that it is virtually impossible for the vehicle owner to “detect” most signs of shock and strut wear – it happens so gradually that it probably won’t be obvious until new units are installed and the consumer can feel the dramatic difference in overall ride quality and control.
The failure of one shock or strut should always trigger a careful inspection and test drive to check the condition of the other three units. If the vehicle has more than 80,000 kilometres on the existing units, the service writer would be smart to mention this to the vehicle owner.
“In virtually all cases when one shock or strut fails, we recommend replacing the corresponding unit on the opposite corner of the vehicle (front to front, back to back),” added Tenneco’s Bill Dennie. “Having one new and one worn unit at the front or rear corners could lead to control issues and might affect vehicle alignment, which can cause accelerated tire wear. So the best approach is usually to replace shocks and struts in pairs. One exception to this rule would be a mechanical failure of a shock or strut – perhaps the mount has broken or the unit is leaking – fairly early in its service life. If the unit on the opposite corner passes your inspection and driving test and has fairly low miles on it, most customers will opt to replace only the unit that experienced a mechanical failure.”
There is lots of ride control work out there. A technician and service writer needs to be aware of the vehicle age and kilometres driven.
“Ride control work requires that time be spent talking to the customer, vehicle maintenance history be gathered, and that the importance of ride control to the control, handling, stopping distance and comfort of the vehicle be communicated,” said Gabriel’s Wittman. “Ride control work may be being missed because of limited dialog with the customer, and because there may not be proper training in vehicle inspection and diagnosis of ride control issues.
“Shops can work to establish dialog with customers and conduct vehicle inspections as a routine step as this helps to produce additional sales beyond the repairs the customer requests. The best solution is a shop that has a customer friendly vehicle inspection area where it is quiet enough to have a conversation with the customer. Doing this helps to build the long-term relationship and customer trust that every shop owner desires, to establish repeat business.”
Dennie said at Tenneco, “We’ve seen studies indicating that a huge percentage of vehicles go to the junkyard with their original shocks and struts. We certainly know that there are millions of vehicles on Canadian roads that need new ride control units.”
Capturing this service opportunity – and helping these customers – requires a formal inspection process in each shop. Ride control inspections and test drives should be part of every brake, tire, chassis and alignment job. And any time you have a vehicle on the lift, you should be looking at all undercar systems for signs of failure or abnormal wear.