Mercury Racing Lower Unit and Gearcase

Mercury Racing 8M0176859 5.44 Inch XL Gearcase

Mercury Racing 8M0176859 is a 5.44 inch XL gearcase assembly with a 1.60 gear ratio and standard rotation. It is used on Mercury Racing 450R supercharged 4.6L V8 Verado platform applications.

This current Mercury Racing gearcase supersedes 8M0159651. Because complete lower unit assemblies are highly specific to shaft length, gear ratio, rotation, engine family, and serial number, confirm your exact application before ordering.

Compatible Applications

OEM & Cross Reference Numbers

What This Part Is Used For

This is a complete lower unit gearcase assembly used to transfer engine power through the driveshaft and gear set to the propeller shaft. The 1.60 gear ratio and standard rotation configuration are designed for specific Mercury Racing performance setups.

Replacement may be required after gearcase impact damage, internal gear failure, bearing damage, housing damage, or a complete lower unit service decision where assembly replacement is preferred over rebuilding.

Key Features and Benefits

• Genuine Mercury Racing gearcase assembly
• Current part number 8M0176859
• Supersedes Mercury Racing 8M0159651
• 5.44 inch gearcase for high-performance applications
• XL shaft configuration
• 1.60 gear ratio with standard rotation
• Designed for select Mercury Racing 450R and 4.6L V8 performance models
• Best verified by serial number, shaft length, ratio, and rotation

FAQ

What does Mercury Racing 8M0176859 replace?

Mercury Racing 8M0176859 supersedes 8M0159651 for this 5.44 inch XL, 1.60 ratio, standard rotation gearcase application.

Does this fit the Mercury Racing 450R?

This gearcase is used on Mercury Racing 450R supercharged 4.6L V8 applications that require the XL shaft, 1.60 gear ratio, and standard rotation gearcase.

Is this the same as a counter rotation gearcase?

No. This page is for the standard rotation version. Counter rotation gearcases use different part numbers and must be matched to the correct engine and boat setup.

What should I verify before ordering?

Verify your engine serial number, shaft length, rotation, gear ratio, and current gearcase part number. Complete gearcase assemblies are application specific and should not be selected by horsepower alone.

Searchable Terms

Mercury Racing 450R gearcase, Mercury 450R lower unit, Mercury Racing XL gearcase, 5.44 inch gearcase, 1.60 ratio Mercury gearcase, Mercury standard rotation gearcase, Mercury V8 Racing lower unit, 450R standard rotation lower unit

Searchable Part Numbers

8M0176859, 8M0159651, Mercury Racing 8M0176859, Mercury Racing 8M0159651

Mercury Racing / Performance Outboard Steering

Mercury 848125 Spiral Lock Retaining Ring

The Mercury 848125 Spiral Lock Retaining Ring, also referenced as 53-848125, is a genuine OEM-style retaining ring used in select Mercury and Mariner high-performance outboard steering and swivel bracket assemblies.

This part is commonly found on performance and racing outboards, including select Pro Max, Super Mag, XS, Sport XS, Offshore, 300X, and 300XS applications. Exact fitment should always be verified by engine serial number and parts diagram before ordering.

Compatible Applications

OEM & Cross Reference Numbers

What This Part Is Used For

A spiral lock retaining ring is used to hold components securely in place inside the steering or swivel bracket assembly. On high-performance Mercury outboards, small retaining parts like this are important for keeping steering and bracket components properly retained during operation.

This part is commonly replaced during steering arm, swivel bracket, clamp bracket, or heavy-duty steering service when the original retaining ring is removed, damaged, corroded, or no longer reusable.

Key Features and Benefits

• OEM-style spiral lock retaining ring for Mercury performance outboards.
• Commonly referenced as Mercury 848125 and 53-848125.
• Used in select steering arm and swivel bracket assemblies.
• Supports service on Pro Max, Super Mag, XS, Sport XS, Offshore, 300X, and 300XS style applications where specified by diagram.
• Small but important retaining component for bracket and steering service.

FAQ

What is Mercury 848125?

Mercury 848125, also shown as 53-848125, is a spiral lock retaining ring used in select Mercury outboard steering and swivel bracket assemblies.

What engines does this retaining ring fit?

It is used on select Mercury and Mariner high-performance outboards, commonly in 2.5L, 3.0L, and 3.2L performance families including Pro Max, Super Mag, XS, Sport XS, Offshore, 300X, and 300XS style applications.

Where is this part used?

It is commonly found in the swivel bracket and steering arm assembly, including short or heavy-duty bracket configurations where specified by the OEM parts diagram.

Should I verify fitment before ordering?

Yes. These assemblies can vary by serial number and bracket configuration, so confirm using your engine serial number and OEM diagram before ordering.

Searchable Terms

Mercury spiral lock retaining ring, Mercury Racing retaining ring, Mercury swivel bracket retaining ring, Mercury steering arm retaining ring, Pro Max retaining ring, 300X retaining ring, 300XS retaining ring.

Searchable Part Numbers

848125, 53-848125