Drive

Suspension: How sports cars get that tight handling, and sedans have their smooth ride

Vehicles have specific “rides,” depending on what they are: a family sedan will ride smoother than a sports car’s harsher suspension, for example, but its steering won’t be as firm.

These characteristics are achieved through a procedure called suspension tuning. “The rubber bushings, shocks, springs, stabilizer bars and tires can all be tuned to reach a specific target,” says Vu Banh, ride and handling senior engineer at the Hyundai-Kia America Technical Center in California. “Depending on what’s desired, if it’s ride comfort or sporty handling, you can adjust these parts to reach that goal.”

It takes about a year to do the job, which begins when engineers receive the first prototype of a new model. “We start tuning and get a rough setting for that one,” Banh says. “Then we get another vehicle that’s closer to the production car, and we’ll put those (prototype) settings in, fix any issues, make more adjustments and continue refining as much as we can.”

Computers are used extensively in vehicle design, but they’re not as useful in suspension tuning, because they can’t accurately simulate rubber. Tuning is a painstaking process of making adjustments and then driving the car to see how it feels, over and over again.

How it’s done depends on the part. Shock absorbers contain hydraulic oil, and if internal valves are adjusted to different oil flow, the shocks become firmer or softer. Engineers can use soft or hard rubber bushings, or different types of springs to achieve various results. Even the tires become part of the process.

“If we come up with a new shock setting, for instance, we’ll possibly (use) a new tire,” Banh says. “Then we’ll work around that, going back and forth with the shock tuning until it meets the target.”

Many new cars now have electric power steering, which uses a motor in the steering column. Unlike hydraulic systems, which use pumps to regulate fluid flow, the motor can be tuned electronically.

Engineers dial in the steering for more assist at lower speeds, such as when manoeuvring in parking lots, and less at higher speeds for easier control on the highway. They also aim for good “on-centre feel,” where the car stays straight without the need for constant steering wheel correction.

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