Flywheel Bolts- Spitfire
October, 1972
A different type of material has been specified for the manufacturing of the flywheel attachment bolts fitted to four-cylinder Triumphs. The change of material affects the tightening torque requirements. Please not that the part number remains unchanged (138526). The new bolt, however, is quite different in appearance and is easily identified.
| Bolt Appearance | Type | Tightening Torque |
| Black (Parkerized finish) | Original | 42 to 50 lb./ft. |
| Bright (Cadmium plated) | Revised | 35 to 40 lb./ft. |
Please advise your workshop personnel of the tightening torque requirements.