BBR News - New forged output shaft for the KLX110/DRZ110

BBR KLX/DRZ110 Forged Output Shaft w/1st Gear $169.95

Developed for the BBR/Monster Energy race team, this forged shaft is the strongest on the market. A must have for high-horsepower motors. Comes with a forged, high-strength 1st gear. The end oiling-hole has been eliminated and the shaft is grooved for proper oiling of 1st gear. 1st gear also rides on a bushing. We consider this to be the strongest design available. We recommend that you use this in combination with our D-Comp camshaft for best results.

Forged for ultimate strength from proprietary steel alloy
• Installs like OEM parts
• Includes bushed 1st gear.

Why use a forging for output shafts? Experts agree that a forged shaft, of identical material, will be stronger than a cast or machined shaft (billet). The reason is that the grain of the material is aligned with the shape of the shaft with a forging. On a machined shaft, unidirectional grain flow has been cut when changing contour, exposing grain ends. This makes the material more likely to fatigue and result in stress cracking.

The metallurgical summary is that directional strength is key to the superiority of forging over cast or billet. According to the Forging Industry Association: “Directional strength is a result of the forging process. In the forging process, controlled deformation results in greater metallurgical soundness and improved mechanical properties of the material. Forging stock is pre-worked to remove porosity. This produces directional alignment (or ‘grain flow’) for important directional properties in strength, ductility, and resistance to impact and fatigue. These properties are deliberately oriented in directions resulting in maximum strength. Properly developed grain flow in forging closely follows the outline of the component. In contrast, bar stock and plate have uni-directional grain flow; and changes in contour will cut flow lines exposing grain ends and render the material more liable to fatigue and more sensitive to stress corrosion.”

Want to learn more about forging? Hit your favorite search engine and type in "forged versus billet". You'll find numerous articles describing, in detail, why forgings are the best choice for formed shafts (especially gear shafts). SAE and the Forging Industry Association all have peer reviewed engineering research papers comparing the two processes. Here are a few links that you might find interesting:
KLX110 in the air