Gearboxes explained

Gearboxes Explained

Is your gearbox whining?

Struggling to get out of gear?

These are some serious signs it’s time for you to get your gearbox repaired. Your gearbox, or transmission, is a highly efficient system essential for the smooth and safe running of your vehicle.

Lose it, and you lose the ability to drive.

This article covers all these questions and more about gearboxes, how they work, what it means when it’s leaking oil and more.

What is a gearbox?

In the most basic sense, a gearbox is a mechanical device that, like any system of gears, is used to increase the output of torque and change the motor's speed.

Your vehicle’s gearbox contains a gear train or a mechanical unit consisting of a series of integrated gears within a housing. These gears are of different sizes, mainly because of the vehicle’s varying demands depending upon the road, terrain & load.

The gearbox is a part of the ‘transmission’ system, where the gears play an essential role in transmitting the engine power to the wheels.

It is, quite literally, a box containing gears.

Signs your transmission needs a repair

Your gearbox is essential for the smooth and safe running of your vehicle, but there may come a time when it needs to be repaired or replaced.

A vehicle’s transmission system is highly efficient. Still, frequent use may mean that it needs professional repairs from time to time. A fully functional gearbox is essential for your safety on the road, so if you notice any of the signs below, take your car to a professional garage as soon as possible.

Whining or rattling noise:

If you hear unusual whining, buzzing or clunking noises coming from your transmission system, this is a sign that your gearbox is in trouble. There are other possible reasons for these noises. Still, if the vehicle is excessively noisy in neutral gear, it shouldn’t be ignored.

Leaking Fluid:


Transmission fluid has a red hue, so consult a professional straight away if you notice any leaking red fluid. Leaking fluid doesn’t necessarily mean the whole gearbox needs to be replaced, but the leak can cause further damage to other vehicle components if left.

Problems shifting gears.

Do you find that you get stuck in gear, stiffer than usual, or seem to ‘fall’ out of gears while driving? Suppose there is any hesitation or resistance when shifting gears. In that case, this is usually a sign of something wrong with a typically highly efficient transmission system.

Burning smell:

A burning smell is usually the symptom of the gears being overheated when in use. This is caused by excess friction due to a lack of transmission fluid. The smell of burnt transmission can also indicate other issues within your gearbox. Still, you should take your vehicle to your local mechanic for further examination in either case.

How often should my gearbox be serviced?

It would be best to get your automatic transmissions serviced every 15 months or 25,000 kms. This can be quicker if your vehicle has sustained heavy use as it causes your transmission to run hot more often.

What does it mean if my gearbox is making a rattling noise?

Vehicle noises differ, depending on the vehicle’s make and model. However, if you hear a sound resembling rattling, buzzing or humming, these are common signs of transmission failure. These noises can relate to various components within the gearbox and should be looked at by a professional.

What does it mean if my gearbox is stiff?

There are several different components within the gearbox that, if damaged, can cause it to become stiff:

  • A master cylinder or release cylinder is damaged or leaking.
  • Damage or malfunction of a synchroniser ring
  • Damaged hub gear
  • Damaged Hub sleeve
  • Not enough gear oil

If your gears feel sticky or stiff, you should see a professional as soon as possible.

What does it mean if my gearbox is leaking oil?

A vehicle’s gearbox system is highly efficient, but frequent use leads to eventual wear and tear.

The gearbox can reach 90 degrees Celsius, which can cause the wearing or cracking of the transmission system’s seals, pipelines and transmission pump, which can lead to fluid leaking. Transmission fluid has a red hue, so you should consult a professional straight away if you notice any leaking red fluid in or around your vehicle.

Visit your local JAX Tyres, and we’ll fix the issue for you.

What does it mean if my gearbox is whining?

Whining from your engine does not point to a specific problem with the transmission as the cause could be several things. However, suppose you hear unusual whining, buzzing or clunking noises coming from your transmission system. In that case, this is a sign that your gearbox is in trouble, and you should get it checked by a professional.

My gearbox is stuck in gear. What do I do?

If your gearbox is stuck in gear, it’s often a sign that a solenoid has gotten stuck.

A solenoid is a coil of wire used to power a starter, and your vehicle’s computer uses them to figure out which gear should be used. Over time, tiny bits of metal and other debris can get stuck in your transmission fluid, which eventually causes a solenoid to become stuck. This often turns your usually red transmission fluid to black.

If this happens or you’re having any trouble with your vehicle’s gearbox, chat to your local JAX to diagnose and fix your transmission issues.

How long should transmission fluid last?

Like other vital automotive fluids, your transmission fluid will deteriorate over time. It can become impaired by tiny bits of metal and other debris from general wear. Transmission fluid will usually last between 50,000-100,000 km. If your vehicle has sustained heavy use, you may need to change your transmission as quickly as 25,000kms.


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