Mercury – Complete Gearcase | SeaCore Bravo Three XR Series | Hard-Coat Anodized Alloy | 8866J07

Overview

There’s a certain calm that settles in when your boat responds exactly the way you expect — that smooth lift onto plane, the quiet push as the props bite, the confidence that your sterndrive is doing its job without complaint. When you spend your weekends chasing horizon lines or weaving through tight channels, you come to rely on the parts beneath the surface more than anything else. The Mercury Marine part number 8866J07 Complete Gearcase is built for boaters who depend on that reliability. It brings back the steady, trustworthy feel you expect from a Bravo Three XR SeaCore system, especially when saltwater and long days start to test everything on board.

Key Features

• Complete gearcase for MerCruiser SeaCore Bravo Three XR sterndrives with 1.81 gear ratio
• SeaCore hard-coat anodized housing built for maximum corrosion resistance
• Tri-Paint protective system adds a multilayer barrier against harsh marine conditions
• XK360 low-copper alloy helps combat long-term corrosion in saltwater environments
• Heavy-duty forged gears and reinforced U-joint engineered for strength and longevity

Engine & Boat Compatibility

• Fits MerCruiser SeaCore Bravo Three XR sterndrives
• Designed for systems using the 1.81 gear ratio
• Ideal for performance cruisers, offshore pleasure boats, sport boats, and premium twin-engine setups
• Suitable for boaters who regularly navigate saltwater, brackish inlets, or high-demand coastal conditions

Performance & Practical Benefits

What you feel when you run a boat powered by a Bravo Three XR system is a blend of smooth control and solid thrust — and that starts inside the gearcase. The 8866J07 delivers a steady, balanced transfer of power, letting your counter-rotating props grip cleanly and push the hull with confidence. Shifts feel crisp. Handling stays tight. And even when you’re maneuvering in a crowded marina or easing into a narrow cove, the response is predictable and smooth.

Saltwater is unforgiving, and that’s where the SeaCore protection earns its keep. The hard-coat anodizing, the Tri-Paint system, and the specialized low-copper alloy all work together to keep corrosion at bay. Instead of worrying about pitting or hidden wear, you get to focus on the ride. Heavy-duty forged gears bring a level of durability you can feel — especially under load, during sharp turns, or when you open the throttle in choppy water. Installation is clean and straightforward, and once it’s in place, the gearcase settles into its job with a quiet, dependable steadiness.

Why Buy OEM

A gearcase isn’t a part you want to guess on. When you choose a genuine Mercury Marine part, you’re choosing components designed specifically for your sterndrive’s architecture. Everything lines up the way it should — the mating surfaces, the internal gear geometry, the protective coatings — all engineered to work as a system. Aftermarket assemblies may be cheaper upfront, but they rarely match the fit, balance, or long-term durability Mercury builds into every SeaCore component. If you want performance without compromise and a drive that lasts season after season, OEM is simply the practical choice.

FAQ

Q1: Which systems does the Complete Gearcase 8866J07 fit?

It fits MerCruiser SeaCore Bravo Three XR sterndrives equipped with the 1.81 gear ratio.

Q2: What makes this better than aftermarket gearcases?

The engineering and the corrosion protection. Mercury’s hard-coat anodizing, Tri-Paint finish, and forged gears deliver durability aftermarket versions can’t match.

Q3: How do I know if this is the correct replacement?

Check that your drive is a Bravo Three XR SeaCore model and confirm your gear ratio is 1.81. If both match, this part number is typically the correct fit.

Q4: Can it be used in both saltwater and freshwater?

Absolutely. It’s built specifically for harsh saltwater conditions, so freshwater operation is easily within its range.

Q5: Is installation straightforward?

Yes. For experienced boat owners or marine technicians, installation follows standard Bravo Three XR replacement procedures with reliable fitment.