A Balancing Act

Wheel-service equipment makes easy work of advanced vehicles.

The telltale signs of unbalanced wheels are easy to catch: vibration in the floorboard or steering wheel at highway speeds, and scalloped or cupped wear patterns on the tire. An unbalanced tire usually means one section of the tire is heavier than others. One ounce of imbalance on a front tire is enough to cause a noticeable vibration in the steering wheel at about 60mph.

But for a busy tech, going from perilous shakes to that new-car ride isn't always a smooth transition, especially given the new complexities of tires and cars in general. Newer, more sophisticated car models are demanding a more complex market of high-tech, and oftentimes more expensive, wheel-balancing equipment.

Diagnosing the shakes

From price to features to training, there are a whole lot of issues involved when selecting, and selling, wheel balancing equipment.

"Reliability and accuracy are interchangeable when selecting this equipment," said Bob Surey, TeamBear USA national sales manager. "And I would also add to that life expectancy. Customers get very frustrated when they have a 5- or 6-year-old balancer and they're told that the parts are no longer available."

More high-end machines measure an array of vibration-related issues, and troubleshoot more than the balancing alone. In most instances of unwanted gyrations, balancing is only part of the problem.

"Companies do more than balance on the assembly line," said David Scribner, product manager for Hunter Engineering. "They are measuring eccentricities … they're measuring radial force, non-uniformities. Tires, in fact, are being match-mounted/assembled by outside contractors at outside plants."

Kevin Keefe, director of marketing at Hennessy Industries, also notices big issues going on from the tire and wheel side, as OEMs have expanded options and continue to introduce more wheel designs to the market.

"A lot of times the root of the problem isn't so much the balancer," Keefe said. "Shafts and cones are usually good for three years or 30,000 cycles. A 10 inch diameter wheel nick will cause 8 ounces of error, and the balancer will show zero.

roblems like these will bring a lot of vehicles back. Consider mounting accessories, not just balancers. Most aftermarket wheels are more eccentric — distributors and salesmen must educate end-users."

From the industry standpoint, that means a big shift for wheel service equipment to do more than balancing. The equipment also needs to have the right features and accessories. It needs to maximize ride-feel.

"Wheel balancers used properly will solve the majority of issues," Scribner said.

A multitasking machine

Vehicles are changing. Car companies are giving consumers more sensitive vehicles. So the expectations of the equipment must also evolve. This can be seen in vehicles that are being built with lighter and fewer suspension components, thus changing things like tire construction.

"A good example is the spring rate tension," Scribner said. "Look at the Ford F-150. The tires today look identical to how they looked 15 years ago. But now they have a much higher spring rate. They were 1,000 pounds per square in compressor rate. They're now 2,000. Because the rate has doubled, any irregularities, any non-uniformities, are greatly magnified.

Chassis are also more sensitive and rigid. Non-balancer related forces have the same symptoms as wheels that are out of balance. Any slight error can lead to balancing issues."

Another factor that can affect wheel balance is wheel weight problems. Newer products are performing better balances with less weight. Scribner noted that the average shop spends about $10,000 per year on lead, and the cost of lead is going up.

"Once you get past mounting errors, which are huge, the next issue is usually wheel weight problems," Keefe said. "This often occurs when weights are pulled off of one vehicle and applied to another, leading to problems like static issues, noise-level or out-of-round, where the tires and wheel assembly are not perfectly round. You can balance a brick, but it's not going to roll."

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