Electronically Controlled Suspension Systems

What is the difference between electronically controlled suspension systems and automatic stability control? And why do you need to know the difference when you’re going to buy a new car?

First of all these high-tech systems are becoming much more common on new automobiles and even some of the less expensive models include them as standard equipment.

Although this technology has been on the market for at least a decade systems that are deployed today look much different than the ones that were used just five years ago. I remember when I was working on an early 90s Corvette the driver’s complaint was a suspension warning light that was staying on.

This Corvette had a switch mounted in the center console just behind the shifter that allowed the driver to select touring or sport mode. The problem with this Corvette was with the electronically controlled shock absorbers. I remember that the repairs were covered under the factory warranty and that the replacement electronic shocks were a $1000 apiece. This is nice to know if you buy one of these cars used.

When the driver selected the sport mode the shock absorber automatically stiffened up. Stiffer shock settings provided less body roll and increased contact between the tire and the road. When the driver selected the touring setting the shock absorber automatically adjusted to provide a softer ride.

Advances in electronic sensors and computer-controlled technology have led to a new generation of suspension systems. Back in the day the simplest systems were the level control type that used an electronic height sensor to control an air compressor that linked to an air adjustable shock absorber.

Today it is more common to see the more advanced type computer-controlled suspension systems that are hydraulic rather than air controlled. The systems use high pressure hydraulic actuators to carry the vehicle’s weight rather than a conventional coil or leaf spring. This allows the suspension system to react perfectly to various operating conditions quickly.

Some of these systems are so advanced they can help the vehicle corner much like a motorcycle leans into a turn. They do this by raising the height of the outside actuators and lowering the height of the inside actuators when going around a curve. Therefore the vehicle can be made to lean in to the turn and provide almost the same effect as if you were on a high banked racing oval.

Automatic stability control is sometimes confused with electronically controlled suspensions. Although stability control can help with handling characteristics it does not use suspension components in its operation. Instead it uses the automobiles ABS system that is already deployed on most new cars.

Stability control offers assistance when the automobile is going around sharp corners, braking, coasting or even during heavy acceleration. The system works by being able to apply the brake calipers individually to help change the geometry and direction of the vehicle. If the brakes are already applied but over steer or under steer is detected by on board sensor the fluid pressure to the appropriate caliper is increased to maintain the driver’s control.

It took us a while to get used to antilock brake systems and traction control technology. But they have been proven to provide a safer driving experience. Automobile safety can be improved by the deployment of electronically controlled suspension coupled with stability control systems. Over time as automotive technologies improve and manufacturing costs come down we may even see them as government mandated standard safety equipment in the near future.

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