Suspension subframes form the connection between the suspension and the vehicle's body and passenger compartment.

These are one of the key areas vehicle manufacturers use to tune the passenger comfort and isolation. This means in many vehicles the bushings that soft heavily-voided rubber is used. As this rubber ages and degrades it allows significant movement in the suspension mounting which impacts traction, handling and control.

In more powerful vehicles the original soft rubber bushings can also contribute to wheel hop under acceleration and significant movement in changing loads or gear changes - all of which sap performance and reduce passenger comfort.