In this study, the analytical and experimental free vibration analysis of rectangular cross-section uniform cracked thin L shaped beam on noise isolating elastic spring, has been made by the finite element method. In the present analysis; vibration characteristics of "L" shaped beams with cracks and springs attachments have been analyzed giving particular attention to vibration control and noise identification aspects. This analysis is made by using the finite element method considering three dimensional motion of cracked L shaped beams, namely, for inplane, and out of plane bending, coupled bending-longitudinal and bending-torsional frequencies as new research aspects in the literature which, the related works are usually in plane uncoupled beam analysis. The L shaped beams were analyzed on clamped-free and free-free supported conditions. The cracks were put only one side of the beam and several types of cracks were modeled by massless rotational and longitudinal springs. The analytical and experimental results were compared with each other and with the results available in the literature, satisfactorily. As a result of analysis, it has been found that; there is a certain decrease on the natural frequencies of the beam that has different cracks, and it is concluded that, it is possible to have an exact detection and control idea about the shape and the largeness of the crack with analyzing the natural frequencies and noise patterns of the parts. The crack model used in this study is mentioned as a linear spring model used in the literature. The analytical and experimental results and comparisons show the efficiency and effectiveness of the proposed method.