The Volvo Parts, Accessories &
Performance Specialists Since 1963

What Is FOUR-C Suspension And Does My Volvo Have It?

2011-04-14 - Kevin Rutledge

The Continuously Controlled Chassis Concept (Four-C)

What differentiates the Volvo Four-C from other chassis concepts is its ability to process enormous amounts of information. Strategically placed sensors on the chassis measure the longitudinal, lateral, and vertical acceleration of the car relative to driving conditions.

There are sensors to measure:

  • the rotational speed and vertical movement of each wheel
  • steering wheel deflection and velocity
  • cornering (yaw rate)
  • engine torque (calculated)
  • braking interventions by ABS and DSTC

Models equipped with FOUR-C have "Comfort" and "Sport" options selectable on the dashboard.

Volvo 4C Active Chassis Buttons

P2 S60R / V70R and P3 R-Design models have an additional "Advanced" suspension setting.

In much the same manner as the human brain, the sensory information is received and immediately acted upon. The Four-C system has a sophisticated microprocessor and software that computes the motions of the car to adapt the hardness of the shock absorbers. The result is that the car is always fluid with the surface of the road.

While the car negotiates varying terrain, the shock absorbers are updated with new information 500 times a second. In essence, the system makes adjustments continuously, and instantaneously.

The Four-C is a first in the world of cars. To develop this totally new technology Volvo collaborated with high-tech system developer Öhlins Racing AB and shock absorber manufacturer Monroe (both leaders in their fields).

The computerized electrical system of the Volvo, known as Multiplex, also sends information to the Four-C system. Under severe braking for instance, the Four-C system receive the braking information a few milliseconds before the brake pads touch the brake disc. By then the Four-C microprocessor has computed how much the braking will cause the front end of the car to dive, and uses this information to set the shock absorbers to maximize control and tire grip.

When the car is accelerating, Four-C receives the corresponding information from the longitudinal acceleration sensor. Similarly, the system passes on information about a sharp deflection of the steering wheel a few milliseconds before the car actually changes direction.

So Four-C can predict what is going to happen, making the pun in its name (foresee) highly appropriate.

At this point, we do not know of a way to remove the Four-C shocks and struts from a vehicle without setting off warning lights, setting fault codes and potentially disabling onboard systems.  Four-C is integrated with the traction control,  braking systems and engine management on your Volvo so removing it is not a simple matter.

Volvo 4C electronically controlled shocks and struts

Four-C shocks and struts have electrical connectors near the bottom of the assembly.