The ability of mobile ad hoc networks (MANETs) to support quality of service (QoS) guarantees is constrained by the scarce bandwidth of the wireless medium and the free node mobility. One consequence of free node mobility is that network topology may change frequently over time. QoS routing is the first step toward achieving end-to-end QoS guarantees in MANETs. However, topological changes cause frequent route breakage and therefore topology stability becomes a very important requirement for QoS routing. To minimize route breakage, it is important to find stable routes that exhibit long lifetimes. We propose an approach to support QoS routing in MANETs. Our approach creates a fixed rectilinear wireless virtual backbone that is robust and stable against topological changes. We examine the stability feature of the proposed virtual topology and study its effect on the ability of the network to support QoS guarantees. We also analyze the connectivity of the proposed virtual architecture, which is a basic requirement for network reliability. Our results show that the proposed model is able to provide more stable QoS routes with delay guarantees. Moreover, packet delivery and call acceptance ratios increase under the proposed scheme.