Twin Disc MG 521 Marine Transmission Parts - Gasket Set Section

Twin Disc MG521 Marine Transmission Parts – Gasket and Seal Kit Section

The Twin Disc MG521 Gasket and Seal Kit is a complete resealing package engineered for one of Twin Disc’s most durable and heavy-duty marine transmissions. The MG521 is often used in tugboats, workboats, ferries, and other demanding vessels where constant torque and long-duty cycles push internal components to their limits. Over time, seals, O-rings, and gaskets naturally wear from oil pressure, heat exposure, and vibration. This comprehensive kit restores complete sealing integrity, helping prevent leaks, maintain hydraulic pressure, and extend the life of your MG521 transmission.

Twin Disc Gasket and Seal Kit for Marine Gear MG521

This premium-grade kit includes:

• All major housing and cover gaskets
  
  

• Input and output shaft oil seals designed for high-pressure retention
  
  

• O-rings, washers, and sealing rings for control valves and passages
  
  

• Drain and filler plug seals for complete leak protection
  
  

Each component is precision manufactured to meet or exceed Twin Disc OEM specifications, ensuring the correct fit, compression, and resilience under continuous marine operation. When installed correctly, the kit restores tight sealing throughout the gearbox, ensuring smooth clutch actuation and reliable oil circulation.

Signs You May Need This Kit

• Oil leakage around the bell housing, output flange, or inspection cover
  
  

• Drop in transmission oil pressure or slow clutch engagement
  
  

• Visible residue near shaft seals or gaskets
  
  

• Vibration or noise indicating hydraulic imbalance or fluid loss
  
  

Replacing these seals and gaskets at proper service intervals prevents performance decline and protects expensive internal components.

Rubber Block for Twin Disc Marine Gears

The rubber block is a torsional dampener designed to isolate vibration between the engine and transmission. This component fits multiple models, including MG5111, MG5111A, MG5114, MG514B, MG514C, MG518, MG516, MG521, and MG527. Over time, exposure to heat and oil causes the rubber to harden or crack, which increases vibration and mechanical stress on the gear assembly. Replacing the rubber block ensures smooth operation, protects clutch components, and helps maintain alignment under load.

Key Benefits of Replacing the Rubber Block:

• Reduces torsional vibration and noise
  
  

• Extends clutch and bearing life
  
  

• Helps maintain smooth power transfer and alignment
  
  

Why Buy Parts For Twin Disc MG521 Transmissions from Diesel Pro Power

• Exact MG521 Fitment: Each kit is built specifically for the Twin Disc MG521—no generic or mismatched substitutes.
  
  

• Marine-Grade Reliability: All components are made from high-quality materials that resist saltwater corrosion, oil breakdown, and temperature cycling.
  
  

• Comprehensive Overhaul Solution: Everything you need for a complete reseal is included in one convenient package.
  
  

• Trusted by 40,000+ Marine Customers: Diesel Pro Power is the leading online source for Twin Disc parts trusted worldwide by shipyards, fleets, and repair shops.
  
  

• Fast Shipping and Expert Support: All MG521 kits are in stock and ready for immediate dispatch, with expert technicians available to confirm compatibility.