Offered by Buckshot Racing #77, the Mercury 2.5 Liter Propshaft (Standard Rotation), OEM Part 840451, is a high-performance replacement designed to meet the aggressive demands of Mercury Racing and other high-output outboard engines.
Engineered for Mercury Sportmaster and Torquemaster lower units, this heavy-duty propshaft is precision-fit for Pro Max, ROS (Race Offshore) motors, and 200XS 2.5L Optimax engines with serial numbers OT997974 and up. This part is essential for serious marine applications and is commonly referenced under several compatible part numbers, including 822820, 822820F1, 840451A03, 840451A1, and 840451A2.
Known in the marine performance world as the "big shaft" due to its 1 1/4-inch diameter, this propshaft delivers superior strength and endurance. It is ideal for high-RPM, high-load conditions, often seen in tournament bass fishing, offshore racing, and high-performance recreational boating.
Whether it’s labeled 840451 or by cross-reference numbers like 822820 or 840451A03, it is widely trusted for its ability to handle torque-heavy setups without flexing or premature wear—critical for boats that push the limits in speed and load.
This standard rotation propshaft is used exclusively in right-hand turning applications and is found in Sportmaster and Torquemaster gearcases—popular choices among performance enthusiasts due to their robust internals and efficient hydrodynamics.
The shaft’s precision-machined splines and bearing surfaces ensure perfect alignment and longevity when used with genuine OEM components, making it an exact-fit solution for demanding environments.
The 200XS 2.5L Optimax engine series—recognized for its unique balance of fuel efficiency and high-performance output—benefits significantly from a strong driveline. When paired with this OEM-standard 840451 propshaft, the engine delivers optimal propulsion, smoother power transfer, and reduced service intervals even under extreme performance conditions like rapid holeshot launches or extended WOT operation.
This OEM shaft is found across Mercury Racing catalogs, high-performance marine distributors, and parts specialists under all the following part numbers: 822820, 822820F1, 840451, 840451A03, 840451A1, and 840451A2. No matter which identifier is used, the product remains consistent—an OEM-quality, standard rotation propshaft designed for Mercury’s 2.5L performance platforms equipped with big shaft lower units.
In summary, the OEM Mercury 2.5L Propshaft (Standard Rotation) #840451, available through Buckshot Racing #77, is a top-tier solution trusted by performance boaters and marine service pros alike. Its proven durability, high compatibility, and precision design make it the go-to component for maintaining the reliability and output of Mercury Racing engines equipped with Sportmaster or Torquemaster gearcases.
Whether your outboard carries the 822820 or 840451A2 part number, this is a race-level performance in an OEM package.
For technical questions or to confirm compatibility, contact Mike Hill at mike@buckshotracing77.com or call (714) 697-1716.