Twin Disc MG 5061 Marine Transmission Parts for Australia - Rebuilt MG5061 Gear Section

Twin Disc MG5061 Marine Transmission Parts — Rebuilt MG5061 Gear Section

The Twin Disc MG5061 family is a compact, work-ready marine transmission series engineered for reliable propulsion in small to mid-size commercial craft and demanding recreational vessels. On this catalog page you’ll find our rebuilt MG5061 options in the most requested gear ratios and case styles, including the straight-case MG5061SC and the 7-degree down-angle MG5061A. Every rebuilt transmission listed here is spin-tested before it leaves our facility, so you receive a unit that engages smoothly, shifts cleanly under load, and builds oil pressure as designed.

This section is organized to help you compare variations at a glance and then dive deeper into selection guidance, model differences, and practical fitment considerations. If you’re upgrading a vessel, matching a repower, or replacing a worn gearbox, the notes below will help you choose the correct MG5061 configuration quickly and with confidence.

Rebuilt MG5061 Options (Spin-Tested)

MG5061 / MG5061SC Straight Case — Popular Ratios

MG5061SC 1.00:1 (Direct Drive)
A zero-reduction, direct-drive choice for applications where prop speed should mirror engine speed. It’s a favorite for vessels requiring crisp maneuverability and minimal drivetrain complexity. Ideal when your propeller sizing and hull form already assume engine-speed parity.

MG5061SC 1.50:1
A versatile mid-reduction ratio that expands propeller selection and helps engines operate closer to their optimal torque band. Common in workboats and utility craft that benefit from improved low-speed thrust without sacrificing cruise efficiency.

MG5061SC 1.70:1
Sits between 1.50 and 2.00 for fine-tuning prop loading. When fuel economy, acceleration, and bollard pull all matter, 1.70:1 often delivers a helpful balance.

MG5061SC 2.00:1
One of the most widely specified ratios in the MG5061 range. The additional reduction supports a larger, more efficient propeller, stronger mid-range thrust, and smoother docking authority.

MG5061SC 2.50:1
Provides notable torque multiplication for heavier hulls, pushboats, and near-shore commercial service where slow-speed control, towing, or frequent station-keeping are key.

MG5061SC 3.00:1
The highest reduction commonly ordered in the straight-case MG5061 series on this page. Leverages a large-diameter prop for exceptional low-speed authority and load-moving capability.

All straight-case MG5061SC transmissions listed above are rebuilt and spin-tested.

MG5061A 7-Degree Down-Angle — Popular Ratios

The “A” variant features a 7-degree down-angle on the output shaft, simplifying shaft alignment and often reducing the engine’s installation height. That 7-degree geometry can create valuable engine-room clearance in many refits and new builds.

MG5061A 1.00:1 (Direct Drive)
Direct-drive response with the packaging benefits of a down-angle output. Helpful when you’re tight on vertical space but want the immediacy of 1:1.

MG5061A 1.50:1
A strong all-rounder that pairs well with cruise-focused setups seeking improved thrust and smoother engagement at harbor speeds.

MG5061A 1.70:1
Ideal for fine-tuning prop load in semi-displacement craft or heavier pleasure boats where acceleration and docking finesse both matter.

MG5061A 2.00:1
A common repower match. The combination of 2.00:1 reduction and 7-degree down-angle can simplify alignment while unlocking a more efficient propeller.

MG5061A 2.50:1
Selected for workboats, patrol craft, and utility vessels seeking higher bollard pull and predictable low-speed control with room to swing a larger prop.

All down-angle MG5061A transmissions listed above are rebuilt and spin-tested.

Understanding MG5061 Variants & Fitment

Straight Case (MG5061 / MG5061SC) vs. 7-Degree Down-Angle (MG5061A)

Straight Case (SC)

• Output shaft is in-line with the input, making it a natural choice when the engine’s crankshaft and propeller shaft need to remain colinear.
  
  

• Typically used where the stringer height, shaft log, and existing engine beds already accommodate an in-line geometry.
  
  

• Great for refits that replace a like-for-like straight-case transmission.
  
  

7-Degree Down-Angle (A)

• Output shaft sits 7 degrees lower relative to the input.
  
  

• Helps lower the engine’s aft end, creating more clearance over stringers and under deck structures.
  
  

• Can reduce or eliminate the need for aggressive shaft-log modifications during a repower.
  
  

Which should you choose?

• If your vessel already has a down-angle box or you’re seeking added space over the transmission for exhaust runs, intercooler plumbing, or service access, the MG5061A is often the efficient path.
  
  

• If alignment with existing shafting and mounts is the priority, the MG5061SC keeps things straightforward.
  
  

Choosing the Right Gear Ratio

Picking the correct ratio is about matching engine torque curve + hull form + propeller diameter/pitch:

• 1.00:1 maintains engine speed at the prop—best for designs already optimized around direct drive.
  
  

• 1.50:1–1.70:1 helps engines stay in their sweet spot under typical cruise loads and offers a wider prop selection.
  
  

• 2.00:1 is a proven middle ground for many displacement and semi-displacement hulls, enhancing acceleration and mid-range thrust.
  
  

• 2.50:1–3.00:1 serve heavier boats, push duty, and applications where low-speed authority, towing, or frequent station-keeping is critical.
  
  

Pro tip: If you’re torn between two ratios, consider your most demanding use case—tight-quarters maneuvering, towing, or long-range cruising—and favor the ratio that best supports that scenario with an efficient propeller diameter.

Rotation, Mounting, and Interface Notes

• Engine Rotation & Output Direction: Match the transmission’s rated direction to your drivetrain plan. The MG5061 series is commonly applied in standard right-hand installations, but verify rotation and output direction against your propeller and shafting plan.
  
  

• Bell Housing & Coupling: Confirm your SAE housing size and drive-plate/coupling interface during selection to ensure a clean mate with the engine flywheel housing and torsional coupling.
  
  

• Mounting Footprint: Straight-case and down-angle units use different geometric envelopes. When converting from SC to A (or vice versa), review clearance at stringers, exhaust elbows, and shaft-seal hardware.
  
  

• Cooling & Filtration: Ensure adequate oil cooling and clean filtration per the gearbox’s operating envelope. A well-sized oil cooler helps maintain consistent engagement feel and clutch durability during long harbor cycles or heavy towing.
  
  

Application Examples (What These Ratios Are Good At)

Harbor Work & Utility Duty

• 2.50:1 to 3.00:1 (SC or A) deliver resolute low-speed push for tug-assists, line-handling, and utility moves. Expect confident gear engagement and authoritative throttle response around docks and piers.
  
  

Coastal Patrol & Light Commercial

• 1.70:1 to 2.00:1 (SC or A) balance cruise efficiency with readiness to maneuver. Useful for rapid response, frequent idle-forward operation, and mixed-speed patrol patterns.
  
  

Recreational Cruising & Sport Utility

• 1.50:1 to 1.70:1 (A) is popular where the 7-degree down-angle simplifies installation in tight engine rooms without compromising acceleration and docking control.
  
  

Direct-Drive Classics & Repowers

• 1.00:1 (SC or A) shines in vessels designed around direct drive with a properly matched prop and hull form. You keep the crisp, “connected” throttle feel that many skippers prefer.
  
  

Why the MG5061 Series Is a Repower Favorite

• Compact, Proven Package: The MG5061 architecture has an earned reputation for practical durability in service—simple to integrate, straightforward to maintain.
  
  

• Flexible Geometry: Availability in straight-case and down-angle forms lets you solve real-world alignment challenges without reinventing the engine beds.
  
  

• Ratio Coverage: From direct drive through 3.00:1, you can size a propeller that suits your hull’s hydrodynamics and your engine’s power band.
  
  

• Spin-Tested Assurance: Each rebuilt MG5061 unit here is spin-tested, so you receive a transmission that has demonstrated clean upshifts, downshifts, and stable oil pressure behavior on the bench.
  
  

Selection Checklist (Save This Before You Order)

1. Case Style: Straight (MG5061/MG5061SC) or 7-degree down-angle (MG5061A)?
   
   

2. Gear Ratio: 1.00, 1.50, 1.70, 2.00, 2.50, or 3.00 to best match your hull and prop.
   
   

3. Engine Housing & Coupling: Verify SAE housing, drive plate, and coupling compatibility.
   
   

4. Shafting & Alignment: Confirm vertical and horizontal offsets, especially when switching between SC and A.
   
   

5. Cooling Path: Make sure your oil cooler and hose runs meet flow and temperature needs.
   
   

6. Controls: Mechanical or electronic actuation plan; cable runs, travel, and neutral safety integration.
   
   

7. Prop & Rudder Plan: Ensure prop diameter and tip clearance remain acceptable with the chosen reduction.
   
   

MG5061SC (Straight Case) — Quick Reference

Best for: In-line replacements, direct-drive classics, refits keeping existing shaft height.
Popular uses: Harbor maneuvering, coastal utility, direct-drive leisure craft.
Ratios on this page: 1.00 • 1.50 • 1.70 • 2.00 • 2.50 • 3.00 (all rebuilt, spin-tested).
Fitment note: Easiest path when your beds, shaft log, and exhaust were built around an in-line output.

MG5061A (7-Degree Down-Angle) — Quick Reference

Best for: Engine-room packaging, improved service access, alignment simplification.
Popular uses: Repowers where deck height and stringer geometry are tight; semi-displacement cruisers.
Ratios on this page: 1.00 • 1.50 • 1.70 • 2.00 • 2.50 (all rebuilt, spin-tested).
Fitment note: That built-in 7-degree down-angle can reduce driveline compromises and help with shaft/log alignment.

How to Think About Propeller Sizing with MG5061 Ratios

While exact propeller math belongs to your naval architect or prop shop, here’s a pragmatic approach that aligns with MG5061 ratio choices:

• Start from Engine Torque Curve: Identify the rpm band where your engine makes durable, fuel-efficient torque.
  
  

• Pick Ratio to Hit That Band at Cruise: Use 1.50–2.00 for many cruising hulls, 2.50–3.00 for heavier or push-duty service, and 1.00 when direct drive is part of the design DNA.
  
  

• Check Tip Clearance: Larger props need adequate clearance to minimize vibration and cavitation.
  
  

• Validate Reverse Authority: Ratios that help low-speed thrust also help reverse control, which is crucial for single-screw docking.
  
  

Service Considerations That Extend Gear Life

• Clean Oil, Correct Viscosity: Fresh, spec-compliant fluid helps clutches engage consistently.
  
  

• Cooler Health: Stable oil temps reduce varnish formation and keep engagement predictable.
  
  

• Shift Discipline: Avoid rapid, repeated forward-neutral-reverse cycles at high rpm; steady shifts preserve clutch life.
  
  

• Shaft Alignment: Re-check alignment after sea trials—settling on mounts can nudge coupling position.
  
  

• Mount Integrity: Sound engine/trans mounts prevent harmful misalignment and shock loading.
  
  

Troubleshooting Symptoms & Ratio Re-Think

• Sluggish Take-Off: Consider a higher reduction (e.g., from 1.50 to 1.70 or 2.00) and prop tweak.
  
  

• Over-Rev at Cruise: Reduction may be too low; a step up in ratio can bring rpm down and improve fuel economy.
  
  

• Docking Feels Abrupt: Sometimes a small ratio increase enables a larger prop with smoother bite at idle-forward.
  
  

• Engine Labors at Mid-Range: Prop may be over-pitched for the ratio; consult your prop shop with sea trial data.
  
  

What You Get With Our Rebuilt Units

• Spin-Tested: Each MG5061 listed here is spin-tested prior to shipping.
  
  

• Ready for Integration: Configured for the ratio and case style you select, with the interfaces you specify.
  
  

• Application Support: Guidance on case geometry, ratio choice, and common fitment pitfalls.
  
  

(If you require accessories such as coolers, couplings, or control components, ask for a coordinated package so everything arrives matched to your MG5061 variant.)

Frequently Compared Within the MG5061 Family

• MG5061SC 2.00:1 vs. 1.70:1 (Straight Case): Choose 2.00:1 for heavier hulls or when you want a bit more idle-forward authority. Choose 1.70:1 for livelier throttle response on lighter boats.
  
  

• MG5061A 2.00:1 vs. MG5061SC 2.00:1: Same reduction benefits; the A adds down-angle packaging advantages if engine-room geometry demands it.
  
  

• 1.50:1 vs. 1.00:1: If you’re moving away from direct drive, 1.50:1 opens prop options and improves maneuvering torque without a dramatic change in cruise characteristics.
  
  

Order Notes & Core Handling

• Core Return: These MG5061 units are sold with a refundable core deposit. Returning a like-for-like core in acceptable condition streamlines your credit.
  
  

• Configuration Confirmation: Before shipment, we’ll confirm case style, ratio, rotation, housing/coupling details, and any accessory requirements.
  
  

• Documentation: Keep your build sheet and any test data with the vessel’s records for future service reference.
  
  

Why Buy from Diesel Pro Power

When uptime matters, you need more than a part number—you need a team that lives marine powertrain. Here’s why vessel owners and commercial operators choose us:

• Spin-Tested Rebuilt Gearboxes: Every MG5061 unit on this page is spin-tested for smooth engagement and pressure stability before it leaves our facility.
  
  

• Application-Driven Support: We help you select between straight-case and down-angle geometry, validate ratio choices, and anticipate integration details like couplings and cooler routing.
  
  

• Fast, Reliable Fulfillment: Coordinated packing and shipment minimize yard time and keep projects on schedule.
  
  

• Proven Customer Satisfaction: Trusted by a large global customer base built over decades of serving commercial and recreational fleets.
  
  

• After-Sale Commitment: From installation clarifications to service intervals, we’re here to help you get the most from your transmission investment.
  
  

Whether you’re modernizing a single-screw cruiser or preparing a workboat for another busy season, our rebuilt, spin-tested Twin Disc MG5061 transmissions—available in both straight-case and 7-degree down-angle variants—deliver the fit, thrust, and control you’re looking for.