SAE 6,5
SAE 6.5 Flywheel Standard – Coupling Fitment Guide
The SAE 6.5 / SAE 6 ½ flywheel standard defines the bolt pattern and flange dimensions for connecting diesel engines to couplings, pumps, and drive components. Established as a global standard, it ensures that engine manufacturers and coupling producers can work together seamlessly, guaranteeing correct alignment and torque transmission.
SAE 6.5 Dimensions (Catalogue Reference):
- Outer diameter (Ø): 215.8 mm
- Bolt pattern (Z): 6 × Ø9
- Bolt circle (DO): Ø200.02 mm
Applications in Couplings:
Coupling producers such as KTR and CENTA manufacture products specifically designed to fit SAE 6.5 flywheels. Examples include:
- KTR BoWex® FLE-PA – torsionally stiff curved-tooth flange couplings.
- KTR BoWex® Elastic – flexible couplings for smooth torque transfer.
- CENTAFLEX-K – elastic couplings developed in cooperation with engine OEMs.
By following SAE standards, couplings can be mounted directly to engine flywheels from leading manufacturers such as Perkins, Hatz, and other worldwide engine brands.
⚠️ Only original OEM couplings guarantee the correct bolt pattern, torque capacity, and material quality. Non-original copies may not align correctly, creating vibration, premature wear, or even engine damage.


