Although dampers and springs have been used for vehicle suspension for a long time, the dampers have been mostly installed independently. This paper deals with a vehicle model where the front and rear dampers are connected by capillary tubes. Expressions for the vibration transmissibility are derived by linearizing the equations of the mass flow through the capillary tubes on the assumption of small variations in volume and pressure of the damper chambers. Theoretical analysis shows that the connected damper system has a preview control effect on the rear ride quality but a low pitch damping without control. A quasi-sky-hook system is introduced for the semi-active control of the connected dampers to improve their performance. The computer simulation results demonstrate a good preview control effect and vibration suppression characteristics of the semi-active system.