The structure of design and technological preproduction of straight bevel gears by precision forging is presented. The mathematical model of modified involute bevel gear with localized contact is described. The modification parameters that control the degree of localization are presented. To select the optimal contact localization the problem of constrained optimization of contact pressure in gears is stated and the new heuristic algorithm for its solution is developed. To ensure the required metal amount in the workpiece for the finishing calibration of the working surfaces of the teeth, the allowance distribution parameters are introduced. The problem of calculating the shape of the allowance is solved. The criterion of correctness of allowance distribution is proposed, which determines what amount of metal in the workpiece is sufficient to fill the shape of the finished tooth. The mathematical models, methods and algorithms are implemented in a software application. The software application is tested on two dozen of straight bevel gears. An example of calculation of one gear is presented in the paper. It was manufactured in metal using precision forging methods at KAMAZ.