The Stainless Steel Prop Shaft Conical Spring Washer is a critical component used in Mercury Racing Hub Kits for high-performance HD Mercury outboard and Mercruiser sterndrives, including the CLE and Sportmaster found on 260 HP, 280 ROS, 300 Drag, 300 Pro Max, 300X, 300XS,  and 4-stroke 250R, 300R, 400R, and 450R outboards. It also fits Fleetmaster, Verado 5.25" Gearcases, and MerCruiser Bravo 1 XR, and XZ I/O Sterndrives.
 
The function of the Prop Shaft Spring Washer:
 
Preload Tension: The primary function of the spring washer is to provide a consistent preload tension on the propeller shaft assembly. This helps to keep the propeller secure and properly aligned during operation.
 
Absorb Vibrations: The spring washer can absorb and dampen vibrations and shocks that occur during the engine's operation, protecting the propeller and shaft from potential damage.
 
Compensate for Wear: Over time, components in the propeller assembly can wear down. The spring washer can compensate for this wear, maintaining the necessary tension and alignment.
 
Prevent Loosening: By providing a constant force, the spring washer helps to prevent the nuts and bolts in the propeller assembly from loosening due to the engine's vibrations and rotational forces.
 
Location and Installation:
 
Location: The prop shaft spring washer is located between the propeller and the thrust washer on the propeller shaft.
 
Installation: Proper installation of the spring washer is crucial. It must be placed in the correct orientation to ensure the necessary preload and tension. Incorrect installation can lead to improper propeller alignment and potential damage.
 
In summary, the prop shaft spring washer in a Mercury Racing outboard motor is a critical component that ensures the propeller remains securely attached and aligned, absorbs vibrations, compensates for wear, and prevents loosening due to engine operation.
 
Includes one (1) Prop Shaft Conical Spring Washer. These should be changed on an annual or regular basis. 
 
Replaces Mercury / Quicksilver OEM Part Numbers: 840389A1, 840389A2, 840389A5, 840389K06, 840389K5, 840389K06, 840389Q06, 12-840383A2, Belleville Washer