Honda’s Civic Tourer lays claim to a ‘world’s first’, in that it is equipped with adaptive damping on the rear axle only. Honda claims that this is beneficial in many areas, with the most important being the ability to “offer comfort and stability at all times”.
According to Reiner Vollrath, development engineer at Honda Motors Europe, the decision to forego a traditional four-corner setup in favor of a rear-axle-only option, is largely down to the identified target audience of the car.
The Tourer pushes the Civic in to the lifestyle segment of cars that are as likely to carry surfboards and bicycles as child seats and family shopping. As a result, the development team investigated the influence that various lifestyle additions can have on the car.
“Under normal loading circumstances, it was found that the most effective point of damping the body motion was on the rear axle,” Vollrath begins. “However, what is becoming more popular is the external, rear-mounted bike-carrier, and it was here that the dynamic behavior was most influenced. The large rear overhang and high mounted load outside the car creates substantial additional body movement on the rear axle.”
What exacerbates this problem even more is that rear-mounted cycle carriers are not subjected to the same speed restrictions as trailers. In combination with the additional 235mm overhang over the hatchback, the Tourer was the ideal candidate for debuting the adaptive rear suspension.
The system uses ZF Sachs Twintube CDCi adaptive dampers, which are combined with a Honda-developed ECU complete with an internal G-sensor. This is used in conjunction with the CAN signals already circulating in the car’s electronic architecture. By using the existing electronic subsystems, and by not adding additional sensors or wiring, Honda claims that its system offers around 75% of the performance of a four-corner set-up, but without affecting weight, electrical consumption and overall cost.
The Honda ECU has been calibrated to take readings from the steering, throttle and brake sensors every 10ms, while the ZF dampers operate on a scale of 35-500% of the original damping force, depending on the Tourer’s loading and damper settings; the driver can choose between normal, comfort and dynamic.
“Some systems on the market have three or four adjustable stage settings,” explains Pascal Papara, project leader, adaptive damper system. “With our system there are no settings. We can run at any point between the hardest setting of 0A, which is also a failsafe mode, to 1.8A with the system continually adjusting as the car travels.”
This means that though there are three fixed settings of normal, comfort and dynamic, all three are overridden in extreme circumstances to deliver the driver the optimum level of grip and stability.