This paper studies the delay consensus margin and its bounds for second-order multiagent systems to achieve robust consensus with respect to uncertain delays varying within a range. This paper attempts to answer the question: What is the largest delay range within which a control protocol is able to achieve and maintain the consensus? We consider second-order agents with unstable poles, which communicate over an undirected network topology, and derive explicit bounds on the delay consensus margin. The results show that the consensuability robustness of such unstable agents depends on the pole locations of the agents, as well as on the eigenratio of the network graph.