Recommended Spare Parts and Kits for Twin Disc MG516 Marine Gear

April 1, 2025

 

Twin Disc MG516 Marine Transmission
Twin Disc MG516 Marine Transmission

Introduction

The Twin Disc MG516 and MG5161 marine transmissions are purpose-built for heavy-duty commercial applications—fishing vessels, tugs, ferries, supply boats, and more. Their robust gear trains and clutch systems offer thousands of hours of reliable service, but like all mechanical systems, they require routine maintenance and eventual overhaul.

Whether you’re a marine operator planning for long-term fleet readiness, or a shipyard preparing for an urgent repair, knowing which spare parts to stock, what’s included in a rebuild kit, and when to repair vs replace the transmission is vital for reducing downtime, avoiding costly failures, and optimizing your maintenance budget.

Parts Catalog for Twin Disc MG516 Marine Transmissions
Rebuilt Twin Disc MG516 Marine Transmissions
Plate Kit For Twin Disc MG516 Marine Transmission
Gasket Kits For Twin Disc MG516 Marine Transmission

This guide provides:

  • A breakdown of full rebuild kits for the MG516
  • A list of commonly replaced wear items
  • Strategic advice on when to rebuild, refresh, or replace
  • Direct sourcing links and aftermarket options

Disclaimer: Always verify compatibility using your Twin Disc MG516 serial number. Consult OEM service bulletins or Diesel Pro Power’s support team if unsure about specific gear ratio or production changes that may affect part fitment.

Rebuild Kits for Twin Disc MG516 Marine Gear

What Is a Rebuild Kit?

A rebuild kit (also referred to as an overhaul kit) for the MG516 contains the critical components needed to restore transmission performance and reliability during a major service. These kits are especially useful during scheduled overhauls or in the event of performance failure.

What’s Typically Included in an MG516 Rebuild Kit?

Component Function
Clutch friction discs Engage power in forward/reverse gears
Steel separator plates Alternate with friction discs in clutch stack
Lip seals and O-rings Seal hydraulic passages and clutch pistons
Shaft seals Prevent oil leakage at input/output shafts
Cover gaskets Seal housing joints
Valve body O-rings Prevent hydraulic pressure loss
Bearings (optional kit) Support rotating shafts and reduce friction
Thrust washers Manage axial play in gear assemblies
Snap rings Secure clutch packs and rotating groups
Filter elements Protect internal parts from contamination
Shims (in advanced kits) Adjust clutch clearance and gear backlash

Diesel Pro Power offers aftermarket rebuild kits for the MG516 that match or exceed OEM material standards, with fast international shipping.

Types of Rebuild Kits Available

1. Standard Rebuild Kit

  • Friction plates
  • Steel plates
  • Seals and gaskets
  • Ideal for units with no gear damage

2. Master Overhaul Kit

  • Everything in the standard kit
  • Plus all bearings, thrust washers, and shims
  • Ideal for complete teardown or worn units

3. Seal-Only Kit

  • All shaft seals, O-rings, and cover gaskets
  • Used when gear and clutch wear is minimal

Why Use a Pre-Packaged Kit?

✅ All parts matched for compatibility
 ✅ Time-saving—no need to hunt individual components
 ✅ Often 25–35% cheaper than buying parts separately
 ✅ Backed by warranty and quality assurance
 ✅ Improved rebuild consistency

Where to Buy MG516 Rebuild Kits

You can source rebuild kits from:

  • Diesel Pro Power – MG516 Kits
     – Offers premium aftermarket kits in stock
     – Kits built from field-proven materials
     – Global shipping + support
     – Same-day dispatch on in-stock items

  • OEM Twin Disc dealers (higher cost, longer lead times)
  • Specialized marine transmission rebuilders (check for markup)

Commonly Replaced Parts for Twin Disc MG516 Marine Gear

Not every job requires a full rebuild. Many routine maintenance tasks, minor leaks, or inspection findings can be resolved with targeted part replacements.

1. Filters

Why It’s Critical:

  • Keeps oil clean
  • Prevents wear from metal particles or debris
  • Prolongs life of clutch packs and bearings

Replacement Frequency:

  • Every 250–500 hours depending on usage
  • Any time oil is changed
  • After a failure or rebuild

Available Types:

  • Spin-on filters (common on most MG516)
  • Cartridge filters (on early or modified models)

Where to Get:

  • Diesel Pro Power – MG516 Filters

2. Gasket Sets

Common Leak Points:

  • Rear housing cover
  • Clutch piston covers
  • Valve body mounting
  • Drain plug and cooler line fittings

Why Replace:

  • Old gaskets compress and harden over time
  • Even if not visibly leaking, aged gaskets risk sudden failure under pressure

Replacement Best Practices:

  • Use new gaskets at every disassembly
  • Use high-temp RTV or anaerobic sealant as needed
  • Avoid reusing gaskets, especially cork or fiber-based ones

3. Shaft Seals

Purpose:

  • Maintain oil pressure
  • Prevent fluid leaks at rotating shafts
  • Protect against water ingress on exposed ends

When to Replace:

  • Any time the output or input shaft is removed
  • If oil leak is observed near flange
  • Every 2,000–3,000 hours, or sooner in harsh conditions

Types:

  • Nitrile (standard)
  • Viton (for high-temp and saltwater environments)

4. Clutch Friction and Steel Plates

Purpose:

  • Transmit torque through forward and reverse clutch packs
  • Alternate between friction (grip) and steel (support)

Signs of Wear:

  • Delayed engagement
  • Slipping under load
  • Burnt smell or discolored oil
  • Uneven clutch stack clearance

Replacement Cycle:

  • Every 5,000–10,000 hours for commercial applications
  • During scheduled rebuilds or performance problems

5. Control Valve Components

Includes:

  • Solenoids
  • Spools
  • Seals and springs
  • Electrical connectors

When to Replace:

  • If shift response is inconsistent
  • After overheating or varnish contamination
  • Faulty solenoid test results or error codes

6. Bearings and Thrust Washers

Function:

  • Support rotating components
  • Control endplay and reduce axial loading

Replacement Triggers:

  • Whining, vibration, or heat
  • Gear or shaft service
  • Worn beyond OEM spec

Tip:

  • Replace in sets to avoid mismatch or premature wear
  • Inspect shafts for scoring when changing bearings

When to Replace vs Rebuild a Twin Disc MG516

Knowing whether to rebuild your MG516 or replace it entirely is a decision that balances cost, downtime, part availability, and labor resources.

Rebuild the MG516 When:

✅ You have no gear tooth damage
 ✅ Housing is intact
 ✅ You have access to quality rebuild kits
 ✅ You can allocate 24–48 labor hours (depending on setup)
 ✅ Your vessel cannot afford long shipping delays

Replace the MG516 When:

 

 

❌ Gears are chipped or broken
 ❌ Case is cracked or warped
 ❌ Input/output shafts are severely worn
 ❌ Core parts are seized, corroded, or beyond tolerance
 ❌ There is no technician access or shop capability
 ❌ A remanufactured exchange unit is available quickly

Cost Comparison: Rebuild vs Replacement

Factor Rebuild Replacement
Parts $2,500–$4,500 $9,500–$16,000
Labor 25–40 hours 8–12 hours
Downtime 3–6 days 1–2 days (if in stock)
Warranty Limited (unless certified shop) 6–12 months (with rebuilt unit)
Risk Higher (depends on tech skill) Lower (pre-tested unit)

Downtime Considerations

If your vessel is on a tight commercial schedule, consider:

  • Having a spare transmission on hand
  • Using modular rebuild kits for in-field clutch replacement
  • Scheduling overhauls during off-season or haul-out periods

Rebuild Lead Time

  • Average overhaul: 3–5 business days (in-shop)
  • Rebuild kit delivery: 1–3 days (from Diesel Pro Power)
  • Labor time: 24–40 hours depending on setup

Replacement Lead Time

  • In-stock reman transmission: Same-day shipping from Diesel Pro
  • Drop-in install time: 1–2 days including alignment
  • Make sure to provide serial and gear ratio for proper match

Maintenance Stock Recommendations for MG516 Operators

If you run multiple vessels or manage a fleet, Diesel Pro Power recommends keeping the following parts on-hand for quick response:

Emergency Spare Parts

  • ✅ 1x Clutch plate set
  • ✅ 1x Full seal and gasket kit
  • ✅ 2x Shaft seals
  • ✅ 2x Spin-on filters
  • ✅ 1x Control valve O-ring pack
  • ✅ 1x Cooler line set
  • ✅ 1x Solenoid assembly (if electronic shift used)

Long-Term Support Inventory

  • ✅ 1x Complete rebuild kit
  • ✅ 1x Output flange hardware kit
  • ✅ 1x Pressure gauge with MG516 adapter
  • ✅ 1x Manual or control system backup cable
  • ✅ 1x Transmission mount bushing set

Having these parts ready eliminates downtime waiting for shipping, customs, or inventory restocks—especially in international ports.

Quality Considerations: OEM vs Aftermarket

OEM (Twin Disc)

  • Known brand reliability
  • High price point
  • Often longer lead times
  • May not stock full rebuild kits

Aftermarket (Diesel Pro Power)

  • OEM-equivalent or improved materials
  • Same-day shipping in most cases
  • Lower total cost of ownership
  • Widely used in commercial fleets worldwide
  • Kits tailored to MG516 serial range and field conditions

Tips for Successful Rebuild Planning

  1. Match your serial number before ordering
  2. Inspect housing and gears before ordering parts
  3. Replace filters and cooler lines during rebuild
  4. Plan labor time for testing and alignment
  5. Document part numbers and sources for future repairs
  6. Store seals and gaskets in dry, temperature-controlled areas

Summary: Recommended Spare Parts and Kits for Twin Disc MG516 Marine Gear

Keeping your Twin Disc MG516 operational over the long haul means having access to the right components—before you need them. By understanding what’s in a rebuild kit, when to replace common wear parts, and how to evaluate the rebuild vs replacement decision, you protect your vessel, your schedule, and your bottom line.

Key Takeaways:

 

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