Lost drive in traffic?
If the car stops moving, won't go into gear or a gearbox warning light comes on with a loud noise or a burning smell, get to the side of the road if you can, switch off and put the hazard lights on. Call roadside assistance if you have it. If anyone is hurt or in danger, call 000.
What kind of transmission does your car have?
It matters, because each one goes wrong differently. A conventional automatic uses a torque converter and sets of gears. A CVT (continuously variable transmission) has no fixed gears: CarsGuide describes pulleys and metal belts instead. A dual-clutch gearbox works like two manuals run by computer. A manual has a clutch you control, and our clutch page covers that part.
If you're not sure, the owner's manual will say, and the mechanic can tell from the make, model and year.
What the gearbox is telling you
| What it can mean | What to do | |
|---|---|---|
| Revs climb but the car doesn't pick up | Slipping: low fluid or internal wear | Check for leaks and see a mechanic soon |
| A pause before it goes into gear | Low fluid, or wear in the hydraulic parts | Get the fluid checked first |
| A shudder at low speed, or under gentle power | Torque converter, fluid, or a CVT shudder | Get it scanned and road tested |
| A whine that gets louder over time | On a CVT, worn pulleys and belts | Stop putting it off: driving on risks more damage |
| Red or brown fluid on the driveway | A leak | See transmission fluid leak |
Do I need a transmission fluid change?
Check your maker's schedule. Some list a fluid change at a set distance. Others call it sealed or don't list one for normal driving. Towing, heat and heavy stop-start work are harder on fluid, so ask the mechanic if your driving fits that.
RACV lists a transmission check in a minor service, and a major service can include changing fluids where the schedule asks for it. Going by the book matters here because automatics, CVTs and dual-clutch boxes each take their own specified fluid, and the wrong one can do real harm.
Ask if it's a drain and refill or a full exchange, and if the filter is included. On a sealed system, CarsGuide says the fluid should not need regular topping up, so a low level suggests a leak. Finding that leak comes first.
What does the mechanic do?
A good diagnosis comes before any quote for a rebuild. The mechanic reads the fault codes, checks the fluid's level and condition, looks for leaks and road tests the car. A lot of problems end there: a sensor, a wiring fault, a leaking seal or a software update.
If it's internal, the gearbox comes out and goes on the bench. The options are usually a repair, a reconditioned unit or a replacement. NSW even has a tradesperson class called Transmission specialist, covering gears, clutches, drive shafts and differentials. That's the kind of mechanic a general workshop will often send this work to.
The car's age and condition decide which option makes sense, so ask for all of them.
What a good written transmission estimate shows
- The fault found and how it was tested.
- Repair, reconditioned or replacement, and which part is which.
- The fluid being used and that it meets the maker's specification.
- Removal and refit, seals, mounts and any software work.
- The warranty on the unit and on the labour, in writing, plus how far it runs.
What you can do, and what to leave
You can
- Stop fully before changing from drive to reverse. RAC WA calls doing it on the move poor practice.
- Look for fresh spots of fluid where you park.
- Note when it happens: cold, hot, uphill, towing.
- Check the owner's manual for what it says about fluid.
Leave to the mechanic
- Checking fluid on sealed gearboxes, which often needs the car on a hoist at a set temperature.
- Topping up, because the wrong fluid can do damage.
- Scan tool work and software updates.
- Anything inside the gearbox.
If it were our car
We'd stop driving it hard the moment the gearbox felt wrong, because a small fault can turn into a big one quickly. We'd pay for a proper diagnosis before agreeing to any rebuild, and we'd want the fluid and codes checked first. If it's a CVT or a dual-clutch box, it's worth going to someone who sees that make's gearbox regularly. Tell us the car, and there's no harm in asking for a second look on a job this size.