Mounting the Subframe-A Correlation of Cradle Mount Dynamics and Vehicle Ride Performance

A designed experiment approach has been successfully employed to study vehicle ride performance as a function of the dynamic properties of an elastomeric cradle mount system. A series of rubber compounds, representing a broad range of combinations of elastic spring rate and loss tangent (damping) as independent variables, were evaluated individually in the cradle mount system. The elastomers studied included natural rubber, polybutadiene, butyl and EPDM. Ride evaluations were conducted using an instrumented 1982 Chevrolet “Celebrity” Coupe (GM A Car) with a four cylinder engine as the test vehicle. Evaluations were made over various road surfaces at the GM Desert Proving Ground. Computer regression analyses of the data predict that certain ride characteristics in this new front wheel drive vehicle are significantly improved with the use of new, very high damping butyl compounds in the cradle mounts.