Next Step Forward

Past is Past – Hunter Moves Ahead With Latest GSP9700 Upgrade

In a more perfect world, tire dealers would be able to readily and accurately diagnose ride comfort complaints by precisely determining whether vehicle, tire, wheel – or all three ®“ was the cause.

Call it misinterpretation or misunderstanding. Call it what you will, but when Hunter Engineering launched its GSP9700, dealers thought they had found that near perfect solution. But instead of using the highly advanced unit to seek out road vibration causes, some dealers were using the GSP9700 to make out-of-round adjustment claims.

And the volume of such adjustment claims – and the high percentage that were rejected by tiremakers ®“ irritated both tire dealers and tire suppliers.

Hunter discovered "a lack of knowledge and training" in the field caused the equipment to be misused. And Hunter acknowledges that it made a few mistakes along the way.

"The biggest problem was that people weren’t using the 9700 right," said Dave Scribner, Hunter’s product manager. Some dealers, even some tire companies, viewed the GSP9700 as a tire uniformity grader, when, in fact, it was intended as an "instrument for solving tire/wheel vibration problems."

Since then, Hunter has worked with tiremakers to review "how the GSP9700 can and should be used," said Scribner. The result is that past misunderstandings are in the past. Now Hunter is looking to the future with an addition to the GSP9700’s capability.

The GSP9700 has been slightly repositioned as a "vibration control system," and Hunter has enhanced field training.

Physically, the GSP9700 has been upgraded. The latest version (GSP9712) features a wider road roller (now 9.5 inches), and a higher torque motor. It still measures radial force vibration by "road testing" tire/wheel assemblies using a roller and hundreds of computer measurements. But roller load has been increased to 1,400 pounds, allowing for tighter measurements.

The GSP9700 can still also measure wheel run-out, with or without a tire, allowing the technician to see if the wheel is the source of vibration. A centering chuck and the software assure the assembly is properly centered on the shaft.

When used correctly, the GSP9700 can spot sidewall stiffness and anomalies in both the tire and wheel, and deliver instant step-by-step instructions to on how to correct the detected problem. And it can aid in high spot/low spot match mounting.

Hunter has now taken the GSP9700 a step further with StraightTrak LFM, a new feature that measures lateral force pull problems. Hunter says that conicity and "ply steer" are the major reasons for lateral force-related tire pull.

StraightTrak uses the "road roller" already on the equipment to take over 200 individual measurements of a tire/wheel assembly. StraightTrak software then compares the measurements of all four tire/wheel assemblies and indicates the level of lateral force in each assembly. Plus, it shows where each should be mounted on the vehicle to minimize pull.

The operator can check different combinations, or interchange tire/wheel assemblies to find the optimum combination, Scribner said.

The lateral force is shown only as an indexed net figure, and tire position combinations show only net effect, making it simple for the operator to understand and adjust.

The StraightTrak system can be added to GSP9702 and above models, said Hunter. Training for both the standard GSP9700 and the StraightTrak add-on is being handled in a variety of ways – online, on-site, at satellite training centers, and in advanced sessions ®“ to make it easier and more cost-effective for dealers. Plus, Hunter offers additional training on vehicle and tire-specific issues online at www.gsp9700.com.

Hunter learned many hard lessons over the past few years. "But we are convinced that providing some measure to compensate for radial and lateral run-out is in the best interest of drivers," said Scribner.