Oil immersed multiple disk brakes (or “wet” disk brakes) are used in a variety of locations in off-highway drivetrains. As a result, such brakes are required to provide different combinations of torque and sliding velocities with respect to the friction material. Increasingly, the versatility and capability of resilient organic friction materials are making these materials the primary choice for such devices. Such brakes are sensitive to different torque-speed combinations, and design of the brakes must take account of these differences. Whenever the brake design is inadequate, failure may occur in the friction material. In general, avoidance of failure may be achieved through brake design. Also, semi-quantitative analysis of material composition suggests that mode of failure and resistance to failure is related to percentages of major constituents in the material, and the nature of these constituents. However, a maximum resistance to all failure modes does not appear practical due to limitations in performance and papermaking technology.