The Callies Ultra UD crankshaft family represents the most reliable and highest performing evolution in shaft design for naturally aspirated applications. Machined from Callies American made 4330 bar stock or proprietary 4340 forgings, this crankshaft was specifically designed for circle track and endurance racing where the least amount of reciprocating weight is demanded, while not sacrificing strength. Improvements over the outgoing XB and XL cranks include more robust pin arms to decrease torsional fatigue, radially narrowed counterweights (versus pendulum-cut), as well as more material around the centerline to virtually eliminate flexing. These changes come together to make the best endurance crankshaft available so that your engine runs better, for longer.
| Stroke | Main | Pin | Cammed for rod length | Part # |
| 3.335 | 350 | 1.888 | 5.700 | SAX-19A-UD |
| 3.335 | 350 | 2.000 | 5.700 | SAX-14A-UD |
| 3.480 | 350 | 1.888 | 5.700 | SAF-19A-UD |
| 3.480 | 350 | 2.000 | 5.700 | SAF-14A-UD |
| 3.500 | 350 | 1.888 | 5.700 | SAG-19A-UD |
| 3.500 | 350 | 2.000 | 5.700 | SAG-14A-UD |
| 3.750 | 350 | 1.888 | 6.000 | SAJ-19A-UD |
| 3.750 | 400 | 2.000 | 6.000 | SAJ-24A-UD |
| 3.800 | 400 | 2.000 | 5.850 | SAK-24A-UD |
| 3.800 | 400 | 2.000 | 5.850 BBC Post | SMK-24A-UD |
| 3.875 | 350 | 2.000 | 6.000 | SAM-14A-UD |
| 3.875 | 400 | 2.000 | 6.000 | SAM-24A-UD |
| 4.000 | 350 | 2.000 | 6.000 | SAO-14A-UD |
| 4.000 | 400 | 2.000 | 6.000 | SAO-24A-UD |
| 4.000 | 400 | 2.000 | 6.000 BBC Post | SMO-24A-UD |
The Callies Ultra UD crankshaft family represents the most reliable and highest performing evolution in shaft design for naturally aspirated applications. Machined from Callies American made 4330 bar stock or proprietary 4340 forgings, this crankshaft was specifically designed for circle track and endurance racing where the least amount of reciprocating weight is demanded, while not sacrificing strength. Improvements over the outgoing XB and XL cranks include more robust pin arms to decrease torsional fatigue, radially narrowed counterweights (versus pendulum-cut), as well as more material around the centerline to virtually eliminate flexing. These changes come together to make the best endurance crankshaft available so that your engine runs better, for longer.
| Stroke | Main | Pin | Cammed for rod length | Part # |
| 3.335 | 350 | 1.888 | 5.700 | SAX-19A-UD |
| 3.335 | 350 | 2.000 | 5.700 | SAX-14A-UD |
| 3.480 | 350 | 1.888 | 5.700 | SAF-19A-UD |
| 3.480 | 350 | 2.000 | 5.700 | SAF-14A-UD |
| 3.500 | 350 | 1.888 | 5.700 | SAG-19A-UD |
| 3.500 | 350 | 2.000 | 5.700 | SAG-14A-UD |
| 3.750 | 350 | 1.888 | 6.000 | SAJ-19A-UD |
| 3.750 | 400 | 2.000 | 6.000 | SAJ-24A-UD |
| 3.800 | 400 | 2.000 | 5.850 | SAK-24A-UD |
| 3.800 | 400 | 2.000 | 5.850 BBC Post | SMK-24A-UD |
| 3.875 | 350 | 2.000 | 6.000 | SAM-14A-UD |
| 3.875 | 400 | 2.000 | 6.000 | SAM-24A-UD |
| 4.000 | 350 | 2.000 | 6.000 | SAO-14A-UD |
| 4.000 | 400 | 2.000 | 6.000 | SAO-24A-UD |
| 4.000 | 400 | 2.000 | 6.000 BBC Post | SMO-24A-UD |