Two types of steel, a high pitting-toughness material displaying excellent performance in relation to the gear tooth fatigue characteristic and a high yield strength material displaying excellent tooth bending toughness, were developed for use in Formula One gearboxes. Optimization of the alloy composition increased pitting toughness, contributing to the achievement of a 740 g weight saving by enabling the thickness of the gear teeth to be reduced. The high yield strength gear material displayed a yield strength in excess of 1900 MPa, and was developed to ameliorate the issue of tooth root fatigue damage originating in bending of the gear teeth under the excessive input forces characteristic of Formula One racing. From 2008, regulations were changed to stipulate the use of a single gearbox for four race events, and the new material contributed to the achievement of increased long-distance reliability.
Article of Honda R&D Technical Review F1 Special (The third Era Activities) (273 - 275)