He adds that there is a multitude of shocks in today's vehicles. The air-ride seat may have a shock on it, the cab is an air-ride cab, and there is air-ride suspension.
OEMs can affect the suspension by stretching the frame or putting a dump body or tank on it.
"They'll put different tires on the steer axle and you have to compensate for moving the load from the steer axle to the tandem," says Nash. "Many times, they don't realize what they are doing when they add things to the original design."
Torque rods are wear items that are very important to the way the suspension works and are often overlooked.
"Technicians need to look at the condition because many times, techs will replace other parts and it may have been because of a torque rod problem and not anything else," says Nash.
"It's so important for the technician to get familiar with the suspensions before laying hands on them," says Roger Elkins, product manager for truck, bus and motor home suspensions with The Holland Group in Holland, MI. "Go to the manufacturer's website to tap into the latest version of the maintenance manual. Technicians also need to spend some quality time with that information, and this is especially important for new technicians. When working on suspensions, they need to look at the system as a whole."
Open communication between technicians and drivers goes a long way for preventative maintenance as well as in troubleshooting current problems. If the driver doesn't start the dialogue, it's up to the technician.
Elkins offers that an alleged bushings problem may not be the root cause.
"Track bars keep drive axles centered underneath chassis and aid in steering," he explains. "If it's a rubber-bushed track bar, the rubber bushings wear out and allow the axle to ‘walk out' from its position and this puts more wear on the suspension."
He says that technicians would probably just replace the bushings. "What should happen is that they should replace the bushings and the track bar. Suspensions are affected by other systems so technicians need to take a systems approach as the root problem may not obvious. My suggestion is that if technicians bump into a situation where they can't determine a root cause, call the OEM tech lines to help with troubleshooting."
Using genuine parts, not only for fasteners and bushings, but for any replacement parts needed is important to Elkins. "They don't call them genuine for nothing," he says. Elkins advises that keeping to original specifications will keep performance of the suspension consistent. Warranties also can be affected if you do not use genuine parts.
"Techs aren't getting enough training," says Nash. "They don't have enough on suspensions as well as enough training on the myriad of components on the entire vehicle. It's not that they don't want training -- they're overwhelmed with work and it is difficult to be out of the shop. Plus, if you don't work on a product soon after the training, you don't retain the information."
He continues, "We need to rethink and change how we deliver training and information. We need to move to a Just-In-Time training opportunity. Techs don't need hours or days of in-depth training because they probably won't ever use all of the information."
Nash feels the biggest training deficit is on the part of the component supplier. "We're not supplying the information the way the tech needs it," he says. "Some component suppliers are working to change that. The big thing that will help is getting the computer into the shop. Online access right to the service bay will go a long way to improve troubleshooting and maintenance."
"Nobody gets enough training because there is so much equipment to know about," says Elkins. He says The Holland Group has teamed up with Kenworth to develop a training module and workbook for dealer technicians that includes technical drawings, reference charts, and details specific to Holland Group products.