Walking the Line

Jan. 1, 2020

Suspension alignment for customized cars

Lifting or lowering a suspension is a great way to give a vehicle a whole new look, but it can also create a whole new batch of handling problems. That's because changing the ride height can dramatically alter the geometry of the underpinnings, so that the factory settings for the toe, camber and caster are no longer suitable. Or the vehicle may have custom components that required specialized settings and service.

For instance, on the 1968 Plymouth GTX 440 Six Pack Wagon above, the suspension had been upgraded with new parts. Yet even after being aligned by professionals, this muscle cruiser still tended to wander — especially on the freeway at high speeds, making it a handful to drive.

Sorting out the problem required taking some precision measurements with some help from industry veteran Scott Brown, at Van Gordon and Brown Performance in Upland, Calif. In performing the alignment, Scott relied on a Hunter Series 811 Alignment System with digital imaging technology.

To analyze the Plymouth's chassis, Brown first checked for correct suspension geometry by simulating a dive situation, such as braking or dips in the road. During this procedure, he discovered that the geometry was completely off the graph on the computer screen, indicating a severe bump-steer condition.

Checking each suspension component, Brown identified the problem as the steering arm installation. A washer that should have been installed above the nut that secured it to the steering box shaft was missing. Even though the nut was tight, it did not quite bottom out against the steering arm. Without the washer, every time the steering wheel turned, the steering arm flexed slightly, causing a change in the geometry of the center-link and tie rods. It was especially bad on the right side because of the nearly three feet of distance from the steering arm.

Once the washer was installed, the problem was solved. The toe-in, toe-out, and camber and caster settings were properly calibrated, and then it was off for a test drive. The Plymouth now drives like a completely different vehicle. The steering is extremely responsive and the vehicle is easy to drive.

Steve Temple is a freelance technical writer and photographer with more than 25 years' experience. He has served as director of sales and marketing for Shelby American and as online editor for major magazines such as Hot Rod, Car Craft and Rod & Custom.