The slotted countersunk screw is used to retain the outer plates of the earlier clutch center assembly. There are three screws used on each plate and are often damaged when removed. Later models from 1972 onward used (3) through bolts in place of the six countersunk screws.
The screw is 1BA x 9/16″ overall length and is threaded into the clutch center body. Used in clutch centers with rubber shock absorbers from 1963-1971. Made in the UK.
The screws secure the outside plates to the clutch center and must be removed to allow access to the internal vane and shock absorber rubbers inside the clutch center body. The screws are usually staked into place with a center punch after fully tightening them to the clutch center body.
The pressure plate must be removed to access the clutch center assembly. Clutch center service is generally performed with the clutch center removed from the clutch hub.