Dealing with carburize case hardened gear distortion and growth is a challenge for the global gear industry. Attempts started in 1978 with computer programs to calculate distortion and growth@ plus residual stress distributions for a gear and evolved by gathering distortion data for a wide range of sizes@ shapes@ grinding allowances with trends for different geometries. A spread sheet program with gear dimensional input@ calculates the distortions and growths@ and then calculates the modified dimensions for required protuberance and theminimum carburized case depth. Case histories illustrate the consequences of various geometries and future developments are discussed.