Twin Disc gearboxes · Authorised dealer · Melbourne
Twin Disc gearbox service and rebuilds.
Standard MG or QuickShift, single or twin. Serviced to Twin Disc’s schedule at your berth where possible and rebuilt in our Spotswood workshop, with a clear rundown of what’s urgent and what can wait.
- Authorised Twin Disc dealer
- Servicing Melbourne boats since 1995
- Full rebuilds in our Spotswood workshop
- At your berth across Port Phillip Bay
Your setup
Which Twin Disc setup do you have?
Twin Disc gearboxes come in a few forms, and each has its own needs alongside the oil. Pick yours to see what we look after.
Most Twin Disc gearboxes behind cruiser and sportfisher diesels are standard MG units, shifted by cable or by electric solenoid. The clutches are applied by oil pressure and cooled by the same oil, so its level, condition and temperature do a lot of the work.
- Oil and filter change, to the lubrication plate
- Suction strainer cleaned
- Oil level set hot, at idle in neutral
- Oil pressure and temperature check
- Heat exchanger and its anodes
- Input coupling check at the housing vents
- Shift linkage and detent check
- Mounts, output flange and alignment
Twin installations
Two gearboxes, one visit.
On a twin-engine shaft boat there’s a Twin Disc behind each engine. We service both in the same visit, so the pair stays on one schedule.
- Both gearboxes serviced in one visit, at your berth where possible
- Oil pressure, temperature and shift feel compared side by side
- A separate record for each gearbox, the history buyers and surveyors ask to see
- Removal, rebuild and refit planned with your yard
What you get
You’ll know exactly where your gearboxes stand.
Every service ends with a plain-English rundown. Each item is marked done, keep an eye on, or needs attention, so you can see what’s urgent and what can wait. Anything beyond the service is quoted first.
- A separate record for each gearbox
- Kept for your warranty and resale history
- What’s due next, so you can plan around the season
Servicing and your Twin Disc warranty
Twin Disc’s owner’s manual says replacement parts must be of Twin Disc origin or equal, and that other parts void the warranty. Your warranty documents set out the terms for your gearbox. We service to Twin Disc’s schedule with genuine Twin Disc parts and record every visit. Your rights under the Australian Consumer Law apply in addition to these terms.
Service rundown
Twin MG-5075A · Shaft drive · 1,100 hours
- Done
Gearbox oil and filters
Changed to the lubrication plate spec.
- Done
Suction strainers
Cleaned. No metal or debris.
- Done
Oil levels
Set hot, at idle in neutral.
- Done
Oil pressure and temperature
Both within the plate figures on sea trial.
- Done
Heat exchanger anodes
Renewed. Port anode was more than half gone.
- Keep an eye on
Starboard input coupling
Some residue at the flywheel housing vents. Inspect at the next service.
- Needs attention
Port shift cable
Not reaching full detent in reverse. Quoted to replace.
- Done
Mounts and alignment
Mounts sound.
Something not right?
Signs your Twin Disc wants attention.
Many problems give a warning first. If you’ve noticed one of these, it’s worth a look before it turns into a lost weekend.
Slipping, or slow to take up drive
Often a sign of low clutch pressure. Twin Disc’s list of causes runs from a low oil level or an idle set too low to a clogged suction strainer, a shift linkage that isn’t reaching its detent, or worn seals inside. A slipping clutch also makes heat, so it’s worth catching early.
The gearbox is running hot
Twin Disc’s causes include the wrong oil level (too high or too low), a failed or blocked heat exchanger, an air leak on the pump’s suction side and a slipping clutch. The normal temperature range is on your gearbox’s lubrication plate.
A rattle at idle that fades with revs
Twin Disc puts gear rattle down to torsional vibration, sometimes cured by raising the idle, and lists a worn input coupling among the causes of noise. A worn damper is commonly reported to rattle at idle and go quiet above about 1,000 rpm.
The boat creeps in neutral
Twin Disc’s causes include a control valve or linkage out of adjustment, worn seal rings and warped clutch plates. The linkage is the easy check. Warped plates mean taking the gearbox apart.
Milky or grey gearbox oil
Water or coolant is getting into the oil. Twin Disc allows no trace of glycol, and a leaking oil cooler is a commonly reported cause. Get it checked before the clutches suffer.
You’ve wrapped a rope or hit something
Twin Disc’s advice is to shut the engine down and inspect the gearbox, and not to run it if in doubt. Carrying on can turn a small problem into a big one.
Timing
Book around the boating season.
A little planning means the boat is ready on the first good weekend, not the third.
78%
of maritime incidents reported in Victoria in 2024–25 were vessel breakdowns, most of them engine failure or running out of fuel.
Source: Safe Transport VictoriaAugust to October
Pre-season service
Book before the rush. November to Easter is our busiest period, so a service in late winter or early spring has the boat ready for the first good weekend.
Book a pre-season serviceNovember to Easter
On the water
Peak boating, and our busiest months. If a gearbox starts slipping, rattling or running hot mid-season, call us.
Easter to July
Bigger jobs
The best time for gearbox rebuilds, coupling and cooler work and haul-outs, with the least boating missed.
Who you're dealing with
An authorised Twin Disc dealer, looking after Melbourne boats since 1995.
We service Twin Disc gearboxes at your berth where possible. Rebuilds come back to our Spotswood workshop, where each gearbox is stripped, measured, rebuilt to Twin Disc specification and pressure-tested before it goes back in the boat.
- Authorised Twin Disc dealer
- Full rebuilds in our Spotswood workshop
- Genuine Twin Disc parts
- Also authorised for Volvo Penta and Yanmar, and a ZF Marine Service Point
Twin Disc gearboxes, old and new
Twin Disc adds letters for the layout: A for down-angle, SC or DC for an offset output, and V or RV for a V-drive. The identification plate on the gearbox shows the model, serial and BOM numbers, and the lubrication plate shows the oil it takes.
Questions
What Twin Disc owners ask us
How much does a Twin Disc gearbox service cost?
It depends on the gearbox model, whether you have one or two, and what’s due on its schedule. We confirm all of that and give you a clear quote before any work starts.
Do I need to bring the boat to you?
Not for a service. We service Twin Disc gearboxes at the berth or on the hardstand around Port Phillip Bay. Rebuilds come out of the boat and into our Spotswood workshop.
How often does a Twin Disc gearbox need servicing?
Twin Disc’s owner’s manual has the oil level checked daily, and the first oil and filter change within 50 hours on a new gearbox. After that, for private boats doing under 500 hours a year, it suggests oil and filter every 1,000 hours or once a year as a starting point (every 500 hours with 15W-40 oil), cleaning the suction strainer at each change. Charter and commercial boats start from every 1,000 hours or six months. Your gearbox’s plates and how you use the boat set the schedule.
When does a Twin Disc gearbox need a rebuild?
Twin Disc recommends overhauling the gearbox at the same time as the engine, and inspecting the bearings then too, so a repower is a natural time to rebuild or replace it. Between overhauls, slipping, new noise, heat or metal in the strainer are reasons to look inside. We strip, measure and rebuild to Twin Disc specification, then pressure-test before it goes back in the boat.
Which Twin Disc gearbox do I have?
Read the identification plate on the gearbox. It shows the model (for example MG-5075A), serial number, bill of material (BOM) number and ratio. Twin Disc parts are matched to the BOM number, so noting the plate details when you book saves time.
I have twin gearboxes. Can you do both at once?
Yes. We service both in the same visit and keep a separate record for each, so the pair stays on one schedule.
How do I book?
Use the booking form at the top of this page or call (03) 9399 5888. We aim to reply within 1 business day.
Ready when the weather is.
Tell us about your Twin Disc gearbox and where the boat is, and we’ll take it from there.