Some of the Aluminum-steel connections in the G30 body structure are produced using a new body joining technique: flow drill screws. These include, for example, the connection between the engine support (Aluminum extruded profile) and the bulkhead carrier support (ultra-high-strength hot-formed steel).
Flow drill screws are driven directly into the body structure. When this happens, the specially shaped tip produces a flow hole and a thread is then cut. This joining technique is used exclusively in production.
G30 Screw connection of engine support/bulkhead
Once a flow drill screw connection has been loosened, it must not be re-joined using flow drill screws.
Otherwise this will lead to a considerable reduction in strength.
In the event of a repair according to Body Repair Level 2 and 3, the flow drill screws are replaced by blind rivets.
Roof support
The G30 body structure has a hydroformed roof support made of steel. This is welded to the roof side frame in line with the B-pillar. By using a hydroformed section it has been possible to reduce the vehicle weight along with increasing the stiffness of the body. On vehicles with a slide/tilt sunroof or panorama glass roof the reinforcement is incorporated in the relevant roof frame.
G30 Hydroformed roof bow