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Outline

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1. Introduction to the Twin Disc MG5050 Marine Gear

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• Overview of the Twin Disc MG5050
• Key Features and Specifications
• Applications in Marine Use
  

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2. Safety Guidelines and Best Practices

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• Importance of Safety When Handling Marine Transmissions
• Personal Protective Equipment (PPE) Requirements
• Safe Handling and Maintenance Practices
• Hazard Identification and Risk Mitigation
  

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3. Installation Procedures

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• Preparing for Installation
• Tools and Equipment Required
• Step-by-Step Installation Guide
• Alignment and Mounting Considerations
• Post-Installation Checks
  

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4. Operating the Twin Disc MG5050

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• Understanding the Gear Operation
• Startup and Shutdown Procedures
• Proper Gear Shifting and Engagement
• Load and Torque Management
  

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5. Routine Maintenance and Servicing

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• Maintenance Schedule and Checklists
• Lubrication and Oil Requirements
• Filter and Fluid Change Procedures
• Common Wear Points and Inspection Routines
  

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6. Troubleshooting and Diagnostics

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• Common Problems and Their Causes
• Noise, Vibration, and Overheating Issues
• Transmission Slippage and Engagement Problems
• Leak Detection and Repair
• Diagnostic Tools and Techniques
  

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7. Disassembly and Repair Procedures

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• Tools and Workspace Preparation
• Step-by-Step Disassembly Guide
• Replacing Seals, Bearings, and Clutches
• Reassembly and Proper Torque Specifications
  

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8. Rebuild and Overhaul Guidelines

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• When to Consider a Rebuild
• Components to Replace in a Rebuild
• Step-by-Step Overhaul Instructions
• Testing and Adjustments After Reassembly
  

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9. Parts and Components Reference

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• Breakdown of Key Transmission Parts
• Identifying and Sourcing Replacement Parts
• OEM vs. Aftermarket Parts Considerations
  

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10. 50 FAQs for the Twin Disc MG5050

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Videos About Twin Disc Transmissions

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6 Reasons Your Twin Disc Transmission Has Low Oil Pressure

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7 Reasons Your Twin Disc Transmission Is Overheating

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3 Reasons Your Clutch Plates in Your Twin Disc Transmission Are Making Excessive Noise

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Bull Gear On A Twin Disc Transmission 

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Rebuilt Twin Disc Transmissions

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Twin Disc MG5050 Marine Transmission Parts Catalog

Introduction: Keep Your MG5050 Running Strong

The Twin Disc MG5050 marine transmission is a reliable workhorse, trusted by vessel owners and operators for its smooth operation, dependable performance, and robust construction. Used in a variety of marine applications—including fishing boats, patrol vessels, and recreational craft—this transmission is engineered for durability and long service life.

At Diesel Pro Power, we make it easy to keep your MG5050 transmission in top condition with a comprehensive selection of essential maintenance and overhaul parts. Whether you’re preparing for a routine service or a full overhaul, we’ve got you covered with the components you need, ready to ship fast.

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Essential MG5050 Parts for Maintenance and Overhaul

Overhaul Plate Kit for Twin Disc MG5050

Our Diesel Pro aftermarket overhaul plate kit for the MG5050 includes the brass friction plates and steel platesrequired for a complete clutch rebuild.

• Engineered for precision fit and smooth clutch engagement, these plates ensure reliable operation and reduced wear on transmission components.

• Constructed from marine-grade materials to withstand the stress, temperature, and load conditions of marine environments.

• An essential component for planned overhauls or preventive maintenance, this kit restores transmission performance and extends service life.

• A cost-effective alternative to OEM kits, delivering high-quality results at a competitive price.

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Gasket Set for Twin Disc MG5050

Our complete gasket set is essential for achieving a leak-free seal during transmission overhauls or routine maintenance.

• Includes main housing gaskets, O-rings, seal rings, and auxiliary gaskets specifically designed for the MG5050.

• Built to withstand high-pressure and temperature conditions, these gaskets prevent fluid leaks that could compromise transmission performance.

• An indispensable component for maintaining system integrity and ensuring long-lasting reliability.

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Rubber Block for Twin Disc MG5050

The rubber block, or torsional isolator, is a key element in protecting the transmission from vibration and stress.

• Absorbs torsional vibrations and reduces noise, contributing to smoother operation and longer component life.

• Compensates for misalignments caused by hull flexing or engine movement.

• Constructed from marine-grade materials for durability in harsh environments, resisting oil, saltwater, and heat.

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Transmission Seal for Twin Disc MG5050

High-quality transmission seals play a crucial role in maintaining fluid integrity and internal pressure.

• Includes input and output shaft seals as well as dynamic sealing solutions designed to withstand the rigors of marine use.

• Prevents fluid leaks and contamination, safeguarding the transmission and maintaining consistent performance.

• Essential during routine maintenance and overhauls to ensure long-term reliability and prevent costly repairs.

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Oil Strainer for Twin Disc MG5050

The oil strainer ensures clean, debris-free oil circulates through the MG5050 transmission.

• Filters out contaminants that can cause premature wear or failure of internal components.

• Designed for optimal flow and filtration, maintaining continuous lubrication and cooling.

• Easy to inspect and replace as part of regular maintenance, ensuring the transmission runs smoothly and efficiently.

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Marine Transmission Specifications & Applications of the Twin Disc MG5050

Overview of the Twin Disc MG5050 Marine Transmission

The Twin Disc MG5050 is a light- to medium-duty marine transmission designed for vessels that require compact packaging, mechanical simplicity, and dependable power transfer. Built for versatility and reliability, the MG5050 is a popular choice for commercial fishing boats, patrol craft, passenger ferries, and recreational vessels that operate in coastal and inland waters.

With a rugged yet lightweight construction, the MG5050 features a hydraulically actuated clutch and is designed to work with marine diesel engines in the 200–300 horsepower range. Its compact size, combined with flexible output options and multiple gear ratios, makes it an ideal solution for vessels with space constraints that still require reliable torque handling and smooth shifting performance.

The MG5050 is engineered for ease of installation, low maintenance, and dependable service over thousands of operational hours—making it a mainstay in fleets around the world.

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Key Specifications of the Twin Disc MG5050

• Type: Marine transmission, hydraulic clutch

• Horsepower Rating (Approximate):

  • Continuous Duty: Up to 250 HP @ 1800 RPM

  • Intermittent Duty: Up to 300 HP @ 2300 RPM

• Max Input Speed: 2500 RPM

• Reduction Ratios Available:

  • 1.47:1

  • 2.00:1

  • 2.45:1

  • 2.95:1

• Rotation Compatibility: Bi-directional; supports left- and right-hand engine rotation

• Input Housing: SAE No. 2 or SAE No. 3

• Flywheel Sizes: 11.5″, 14″, or as specified by application

• Clutch Type: Oil-cooled, hydraulically actuated multi-disc clutch

• Cooling System: Integrated oil pump and oil-to-water heat exchanger (standard)

• Lubrication System: Pressure-lubricated with internal oil pump

• Oil Capacity: Approximately 5–6 quarts

• Weight (Dry): Approximately 275–325 lbs depending on ratio and configuration

• Mounting: Available with straight or down-angle output; flexible or rigid mount

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Common Marine Applications for the MG5050

The MG5050 is built for applications that require dependable performance in mid-range diesel power systems without the weight or complexity of a heavy-duty gearbox. Common marine uses include:

• Commercial Fishing Boats: Ideal for lobster, crab, and inshore trawlers operating with medium-horsepower diesels.

• Pilot and Patrol Vessels: Offers quick response and reliable shifting for harbor security, search and rescue, and utility vessels.

• Tour and Passenger Boats: Found in ferries and sightseeing boats where smooth, low-vibration propulsion is required.

• Recreational Yachts and Sport Fishing Boats: Used in custom builds and repowers where space is limited but performance is essential.

• Harbor Utility Boats: A good fit for tenders, line boats, and small workboats requiring light-duty powertrains.

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Most Common Engine Models Paired with the Twin Disc MG5050

The MG5050 is often matched with inline-six and inline-four marine diesel engines producing up to 300 horsepower. It integrates seamlessly with popular engine families from Cummins, Perkins, Caterpillar, John Deere, and others, particularly those with SAE 2 or SAE 3 flywheel housings.

Cummins Marine Engines

• Cummins 6BT / 6BTA 5.9

• Cummins QSB 5.9

• Cummins QSB 6.7
  Well-suited for small workboats and patrol vessels, these engines offer excellent torque curves that align well with the MG5050’s gearing.

Perkins Marine Engines

• Perkins 6.3544

• Perkins M300C
  Perkins diesel engines, commonly used in sailboat auxiliaries and coastal commercial vessels, pair well with the MG5050 for reliability and simplicity.

Caterpillar Marine Engines

• Caterpillar 3054C

• Caterpillar 3116 (light-duty configurations)
  These Caterpillar models provide a smooth, consistent torque output that works well with MG5050 transmissions in tour and transport vessels.

John Deere Marine Engines

• John Deere 4045TFM75

• John Deere 6068SFM50
  Common in mid-size marine propulsion systems, these engines pair well with MG5050 gearboxes in patrol boats, harbor craft, and service vessels.

Yanmar Marine Engines

• Yanmar 6LY2 and 6LY3 Series
  A frequent pairing in repower projects for recreational and light commercial vessels due to Yanmar’s reputation for reliability and efficiency.

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Advantages of the Twin Disc MG5050

• Compact Size: Fits into tight engine rooms where larger transmissions may not be feasible.

• Hydraulic Clutch Operation: Smooth engagement and low vibration, ideal for passenger vessels and light-duty workboats.

• Gear Ratio Flexibility: Multiple reduction options to match different hull and propeller combinations.

• Proven Durability: Engineered for reliability under daily commercial use.

• Easy Maintenance: Designed for access to wear components, clutch packs, and seals without special tooling.

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Ideal Use Cases for the MG5050