Given the ongoing driver shortage, it is important to keep your current drivers happy. When drivers complain about vibration issues with their vehicles, it is imperative to troubleshoot and solve the problem quickly. Truck ride complaints can be initiated by many different vehicle conditions. In addition to tire and wheel assembly issues, vehicle components such as clutch, transmissions and drive shafts can all adversely affect ride quality and lead to vibration complaints.
Troubleshooting the specific vibration complaint involves gathering as much information as possible about the specific complaint. It is like playing the “20 questions” game to drill down to the specific cause of the vibration. Some of those questions include:
- Has the problem been occurring for a long period of time or is it more recent?
- If the problem is recent, what has changed?
- Are there any unusual or odd vehicle handling characteristics associated with the vibration?
- What is the engine RPM and speed when the vibration occurs?
- Is the vibration problem felt when the transmission is in neutral and the vehicle is coasting?
Vibrations that occur between, for example, 50 to 60 MPH but disappear either under 50 or over 60 MPH are usually the result of a tire, wheel and/or hub excessive runout leading to imbalance.
If you take the truck out of gear at road speed and the ride disturbance is eliminated, then the vibration is probably related to engine or driveline and not tires. Taking a road test with the vehicle and its driver usually helps to better understand the complaint. The goal is to try to identify which axle or wheel position is causing the vibration.
Another question to ask is, “Where is the vibration felt the most?” If it is felt through the steering wheel and/or under the driver’s seat, that points to a steer tire issue, but if it is felt in the driver’s seat, then one of the drive tires is usually the culprit.
During the road test, if the trailer is disconnected and the vibration disappears then the disturbance is typically related to the trailer tires, wheels or hubs. Additionally, if you altering the fifth wheel position and the vibration goes away, that also points to the trailer tires, wheels or hubs.
If the tires appear to be the source of the vibration, then it is time to examine the tire and wheel assembly. Tires should be thoroughly inspected, including checking for proper inflation pressure, flat spots, irregular tire wear, sidewall bulges and punctures. It is always important to check for concentric bead seating which will clearly lead to vibration complaints.
If the tire is a retread, then confirm that the tread is uniform around the tire circumference. If the tires are duals, double check that the tires are not mismatched. Both dual tires should be within 5 PSI of each other and the tread depths as close as possible. You don’t want a new deep lug drive tire mated with a worn out or low tread depth tire. The tire revolutions per mile will be significantly different, leading to irregular wear and possible vibration complaints.
Another common source of vibration issues is improper wheel nut torque. Loose wheel nuts will cause excessive bolt hole wear and metal fatigue, with the result being wheel vibrations. Also confirm that the tire wheel assembly is properly mounted to the hub, and always use the correct wheel system components when mounting.
Improper vehicle alignment may also be a source of vibration. Be sure to check the total vehicle alignment. In some cases the tractor may have perfect alignment but the trailer is completely misaligned. A badly aligned trailer can cause the tractor to dogleg to the left or right as the vehicle is rolling down the highway.
As a last resort, if you can’t pinpoint the cause of the vibration complaint, then work with your vehicle manufacturer, suspension manufacturer and, of course, your local tire representative for their assistance. The ATA’s Technology and Maintenance Council publishes several recommended practices related to vehicle vibration issues and is a good source of additional information on this subject, which you can find on its website.