Geometric/mechanical isolation of aluminum to steel joining at trim edges for corrosion protection

A method of forming a joint for a motor vehicle body, the method comprising the steps of:

• fabricating a first structural member from aluminum metal;
• fabricating a second structural member from steel metal having an adjoining portion and a ramp portion terminating in a bare exposed edge on the second structural member and upon which the bare exposed edge is disposed and wherein the second structural member is a hydroformed tube;
• and
• attaching the second structural member to the first structural member, wherein the adjoining portion of the second structural member is in substantially juxtaposed abutting relation with the first structural member when the second structural member is attached to the first structural member and the bare exposed edge is displaced from the first structural member to form a gap between the first structural member and the bare exposed edge to prevent corrosion of the bare exposed edge without the use of adhesives and sealants.