By Paul Abelson
senior technical editor
Q: My 2005 International started shaking up front. It wasn’t too bad when it started, but it got worse. My dealer balanced the steer tires and checked front-end alignment. There was some uneven tire wear, mostly on the inside, so the dealer swapped the tires side-to-side. The shaking was still there, and it seemed to be pulling to one side.
The dealer wants to replace all sorts of parts, but I don’t want to finance his exploring with my truck, if you get what I mean. What should I do?
A: Ride and handling are among the most difficult complaints to diagnose. That’s because so many parts and components are involved, and the combinations of things that can go wrong are seemingly endless.
Your dealer went after some of the more common causes. He should have referred to Recommended Practice RP648 “Troubleshooting Ride Complaints” from the Technology and Maintenance Council. It classifies ride problems into seven major ride condition types: vibration, shimmy, harsh ride, handling, pitch or backslap, stability and bounce.
When we spoke, we zeroed in on vibration and handling. You had the tires balanced on the wheel, but not the wheel end assembly. It includes the hub, brake drum and fasteners. With the wheel and tire, they make up the rotating mass. It is not uncommon for a hub or drum to lose balancing weights. That causes vibration and will generate uneven tire wear.
When I used to race, we spin-balanced on the car. The entire wheel end was balanced together. Your dealer can check hub and drum balance. If all the parts are balanced separately, they will be in balance together. There are alternatives, including balance rings and granules or beads placed inside each tire. They react to the entire mass.
Another common problem affecting ride quality is total vehicle alignment. You had your front wheels aligned, using the frame as a reference. Drive axles can shift, inducing side thrust, contributing to the pulling in the steering.
You can quickly check for total vehicle alignment with string and markers. Put a mark on the string. Have a friend hold the mark at the exact center of your steer axle hub. Take the string to your front drive axle hub. Pull it tight and mark the exact center. Do it again at the rear drive axle. Repeat the process on the other side. Compare distances. They should be virtually identical. If not, you need total vehicle alignment.
Worn shocks cause vibration. Your dealer only looked for leaking shocks. To tell if they’re working, drive about 10 or 15 minutes. Put your hand on the shock’s dust cover. It should be warm, indicating the hydraulic fluid was doing its job.
The suspension itself can create problems. Worn bushings allow vibration that, in turn, wears the bushings more and causes greater vibration. Your dealer didn’t find any air bags leaking or any damage to torque rods, but you didn’t mention checking ride height.
TMC has a separate document, RP634, “Ride Height Concerns and Adjustment Procedures for Air Ride Suspension.” Shade-tree mechanics are known to alter ride height in the mistaken idea that it will improve ride and stability. The opposite is true.
These are a few of the steps involved in correcting ride and handling problems. RP648 defines problems, identifies components and provides a framework for checking, then repairing or replacing parts logically. It was developed specifically to prevent maintenance by trial and error.
Get these RPs from TMC, or join and get the full set at no extra cost with your membership. Even if you don’t do your own maintenance, the Recommended Practices can save you money by guiding your service provider. LL
Paul Abelson can be reached at firstname.lastname@example.org.