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Twin Disc MG502 Rebuilt Transmissions & Parts Catalog

Introduction: Power and Precision for Smaller Marine Vessels

The Twin Disc MG-502 marine transmission is an exceptional choice for pleasure craft, sportfishing boats, and small commercial vessels. Renowned for its reliability, smooth operation, and compact size, the MG-502 is engineered to deliver consistent power and performance in light to medium-duty marine applications. With over 40,000+ satisfied customers, Diesel Pro Power offers a comprehensive selection of MG-502 parts to keep your vessel running strong.


Specifications of the Twin Disc MG-502

  • Type: Marine Transmission

  • Power Rating: Suitable for light and medium-duty applications

  • Typical Applications:

    • Pleasure yachts and sportfishing boats

    • Charter boats and harbor taxis

    • Small passenger ferries and tour boats

    • Dive boats, patrol boats, and pilot boats

  • Features: Compact design, smooth engagement, fuel-efficient operation, low maintenance


Rebuilt Twin Disc MG-502 Transmissions: Reliable Performance, Tailored Gear Ratios

A rebuilt MG-502 transmission offers a highly cost-effective solution to extend the operational life of your vessel, especially when compared to the cost of purchasing a brand-new transmission. Diesel Pro Power’s rebuilt units are meticulously reconditioned to meet and even exceed original equipment manufacturer (OEM) standards. Each unit undergoes comprehensive inspection, cleaning, and reassembly to ensure optimal performance and longevity.

Our rebuilt transmissions are not only restored to like-new condition, but are also tested under real-world conditions to verify their performance. From the replacement of worn components to the recalibration of critical systems, every rebuilt MG-502 is designed to provide the reliability and smooth operation that marine professionals demand.

Available Gear Ratios for the  Rebuilt Twin Disc MG-502 Transmissions

Our rebuilt MG-502 transmissions come in the following gear ratios, each optimized for different marine applications, offering flexibility to match your specific vessel’s engine nd usage profile:

  • Rebuilt Twin Disc MG502 Gear (1.54:1 Ratio): 

This gear ratio is perfect for vessels that require a balance of speed and moderate torque. It’s ideally suited for sportfishing boats, high-performance pleasure craft, and vessels where acceleration and cruising efficiency are equally important. The 1.54:1 ratio enables vessels to achieve quick planing speeds, while still providing enough thrust for responsive handling in various conditions.

  • Rebuilt Twin Disc MG502 Gear (2.00:1 Ratio): 

A versatile choice for vessels that need a higher thrust-to-speed balance. The 2.00:1 ratio is commonly used in heavier recreational vessels, charter boats, and harbor ferries that require more torque for maneuvering and maintaining stability under load. It provides a noticeable increase in propeller thrust, improving the vessel’s ability to handle varying sea conditions and passenger capacities.

  • Rebuilt Twin Disc MG502 Gear (2.47:1 Ratio): 

This gear ratio is tailored for applications that require maximum low-speed thrust, such as dive boats, tour vessels, and other operations where precise, slow-speed control is essential. The 2.47:1 ratio delivers exceptional pulling power, ideal for maintaining stability in strong currents or when navigating tight docking spaces. It’s perfect for operations that prioritize safety, reliability, and precise handling over high speed.

Key Benefits of Rebuilt MG-502 Units

  • Precision Engineering: Every rebuilt MG-502 transmission is crafted to OEM specifications, with a focus on quality assurance at every stage of the rebuild process. Components are inspected, reconditioned, or replaced as necessary to ensure the final product performs as well as or better than new.

  • Custom Fit for Your Vessel: With multiple gear ratios available, you can select the ideal configuration that matches your vessel’s engine performance, operational needs, and cruising conditions. This ensures maximum efficiency, reliability, and responsiveness on the water.

  • Warranty Protection: Diesel Pro Power stands behind every rebuilt MG-502 transmission with a limited warranty, offering you peace of mind and assurance of product quality and reliability. Our commitment to excellence means you can count on your transmission for years of dependable service.

  • Budget-Friendly Solution: A rebuilt transmission provides a cost-effective alternative to purchasing a new unit, allowing vessel owners to maximize their investment while maintaining top-tier performance. Whether for a pleasure craft, charter boat, or light commercial vessel, a rebuilt MG-502 from Diesel Pro Power delivers significant savings without compromising on quality.

  • Fast Availability and Expert Support: Diesel Pro Power maintains a comprehensive inventory of rebuilt MG-502 units, ensuring fast order fulfillment and delivery. Our knowledgeable team can help you select the right gear ratio and provide technical support throughout the installation and maintenance process.


Essential Parts for MG-502 Maintenance and Overhaul

Plate Kits for Twin Disc MG-502

Our plate kits include friction plates, steel plates, seals, and rings—everything you need for a smooth rebuild.

  • Designed for marine use, ensuring reliable performance and long service life.

  • Maintains smooth clutch engagement, reducing wear on transmission components.

Overhaul Gasket Sets for Twin Disc MG-502

A complete gasket set ensures that your MG-502 stays sealed and leak-free after maintenance.

  • Includes main housing gaskets, O-rings, seal rings, and auxiliary gaskets.

  • Prevents leaks and withstands the harsh marine environment.

Bearings for Twin Disc MG-502

Essential for smooth operation and longevity:

  • Input shaft bearings for handling engine torque.

  • Output shaft bearings for supporting propeller load.

  • Thrust bearings for maintaining axial alignment.

  • Reduces friction and noise, extending the life of your transmission.

Oil Pumps for Twin Disc MG-502

The oil pump is the heart of lubrication for the MG-502, ensuring continuous oil flow and cooling.

  • Maintains optimal pressure, even under demanding conditions.

  • Prevents oil starvation and keeps your transmission components well-lubricated.

Rubber Blocks for Twin Disc MG-502

Rubber blocks, also known as torsional isolators or flexible couplings, are critical components that connect the transmission output flange to the propeller shaft. These blocks absorb torsional vibrations and misalignments, protecting both the transmission and downstream components from stress and potential damage.

  • Vibration Dampening: Rubber blocks effectively isolate the transmission from torsional vibrations generated by the engine and propeller, reducing noise and wear.

  • Compensation for Misalignment: Flexible design accommodates slight misalignments between transmission and shaft, which is common in marine environments due to hull flexing and engine movement.

  • Extended Component Life: By reducing shock loads and vibrations, rubber blocks help extend the lifespan of critical transmission and drivetrain parts.

  • Marine-Grade Durability: Constructed from high-quality materials resistant to oil, saltwater, and extreme temperatures, ensuring long-term reliability in marine conditions.

  • Easy Replacement: Designed for straightforward installation and replacement during transmission servicing or overhauls.


Additional Resources

Practical Guide To Servicing Your Twin Disc MG502

Introduction


  • Overview of the Twin Disc MG502 Marine Gear

  • Importance of Regular Maintenance

  • Safety Precautions

1. Understanding the Twin Disc MG502 Marine Gear


  • Basic Components and Their Functions

  • Operational Principles

  • Common Applications


2. Pre-Service Checklist


  • Required Tools and Equipment

  • Safety Gear and Precautions

  • Inspection Steps Before Service

  • Maintenance Schedule Overview


3. Disassembly Instructions


  • Preparation for Disassembly

  • Step-by-Step Disassembly Process

  • Identifying Wear and Tear Components

  • Handling and Storing Components


4. Inspection and Diagnostics


  • Visual Inspection Techniques

  • Identifying Common Faults (e.g., Leaks, Cracks, Wear)

  • Diagnostic Procedures for Malfunctions

  • Measuring Tolerances and Clearances


5. Cleaning and Maintenance Procedures


  • Cleaning Guidelines for Major Components

  • Lubrication Requirements

  • Seal and Gasket Replacement

  • Best Practices for Preventing Corrosion


6. Reassembly Instructions


  • Pre-Assembly Checklist

  • Step-by-Step Reassembly Guide

  • Torque Specifications for Fasteners

  • Testing Component Alignment


7. Final Testing and Operational Checks


  • Initial Testing Procedures

  • Load Testing and Calibration

  • Noise and Vibration Checks

  • Post-Service Inspection Checklist


8. Troubleshooting Common Issues


  • Difficulty Engaging Gear

  • Excessive Noise or Vibration

  • Fluid Leaks and Seal Failures

  • Overheating Concerns

  • Control System Malfunctions


9. Maintenance Schedule


  • Daily, Weekly, and Monthly Maintenance Tasks

  • Seasonal Checks for Marine Environments

  • Component Life Expectancy and Replacement Guidelines


10. Recommended Spare Parts and Tools


  • Essential Spare Parts List

  • Recommended Tools for Onboard Repairs

  • Tips for Efficient Parts Replacement


11. Safety and Compliance Considerations


  • Environmental Regulations for Marine Equipment

  • Waste Disposal and Recycling of Old Parts

  • Best Practices for Safe Operation


12. Storage and Preservation Tips


  • Long-Term Storage Preparations

  • Preventive Measures Against Environmental Damage

  • Periodic Checks During Storage

Frequently Asked Questions (FAQ) About The Twin Disc MG502 (Marine Gear)


Disclaimer: For more technical and detailed instructions, refer to the OEM service manual provided by Twin Disc Incorporated. This guide is intended for general maintenance assistance and does not replace official service protocols.


Why Choose Diesel Pro Power?

  • 40,000+ satisfied customers and growing

  • Comprehensive Inventory: Everything from rebuilt transmissions to overhaul kits, bearings, and pumps

  • Expert Support: Our knowledgeable team ensures you get the right part the first time

  • Fast Shipping: Reliable delivery to get you back on the water quickly


Conclusion: Ready to Power Your Vessel with Confidence

Whether you're operating a pleasure yacht, a sportfishing boat, or a small commercial vessel, Diesel Pro Power has the Twin Disc MG-502 parts you need. Our selection of rebuilt transmissions, plate kits, gasket sets, bearings, and oil pumps is designed to help you maintain optimal performance and reliability on the water.

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