Explained: How a gearbox works in a car

For the majority of drivers on the road, the gear stick is one of their most used items in a car after the steering wheel and pedals, but quite often it’s not explicitly clear how one works.

Within your car’s gearbox, as the name suggests, is a collection of gears that allow the driver to manipulate the speed of the car owing to the conditions – such as driving up tall hills. The speed your engine rotates is much higher than that of your wheels, so the gearbox is necessary to help maintain the speed you intend for the wheels.

A shaft running from the engine, via the clutch, is connected to a separate shaft sending power to the driving wheels via a series of cogs, or gears. When you press the clutch, it disconnects the engine from the gearbox, allowing the engine to continue turning without powering the wheels. Each time you change gear, you engage another gear within the gearbox, which is set to send power to the driving wheels at different rates depending on which gear you’re in.

If your gearbox is giving you too much trouble to consider repairing, or it just doesn’t seem to be able to shake a recurring issue, you may find that scrapping your car – or selling for salvage – is the quickest, easiest and most cost-effective solution available to you. By selling your car with Scrap Car Comparison you’re guaranteeing the very best price available, and we’ll even come and collect it from you, totally free of charge.

How much does a new gearbox cost?

If you’ve found yourself in a position where the only option is to get a new gearbox, then you should be bracing yourself for a large sum of money leaving your bank account and heading to the nearest garage. As is often the case with predicting the price of repairs or replacements, everything depends on the age, make, model and level of specification of your car itself. As a general figure though, you should be prepared to be spending north of £1000 to get yourself a new gearbox in place of the broken old one. 

Why is my gearbox making noise?

Hearing noises from your car that you weren’t expecting never feels great, particularly if it’s coming from something as significant as your gearbox. While quite often the cause of unwanted sounds can be attributed to bearings, gears or shaft wear, we’ve made a list of some of the common sounds you could hear and what might be causing them. 

  • Grinding – the grinding of gears is often a sign that someone hasn’t used their clutch correctly and can often be quite a shocking sound and feeling. While it can often be user error, if you’re finding that you’re grinding your gears at an alarmingly regular rate, you could be seeing signs of a clutch problem. If you’re concerned, take it to your local garage to have a look at your clutch.
  • Slamming – if your gears make an unnerving slamming sound every time you change gear, it could be a sign that your transmission pressure or fluid is low. If you’re capable, check the levels of your transmission fluid and you could sort the problem, however for the safest option take it to an expert. Slamming could also be a sign of worn components.
  • Slow shifting – while not a sound, as such, if you’ve noticed that your gear changes are slower than usual, you might find you have a clogged transmission filter. Simply cleaning the filter out should result in your changes reverting back to their usual pace.
  • Humming – a humming sound tends to suggest that a gearbox bearing is wearing out. Beware, though, as these sounds could actually be coming from a wheel bearing instead – if unsure get a professional to check it over.
  • Whining – whining sounds could be a sign that your transmission fluid pump, however, like humming, it could actually be coming from somewhere else within the car, so if you’re unsure, it’s again best to ask a professional.
  • Clunking, Clicking or Rattling – If your gearbox is making a clunking, clicking or rattling sound, take it to a garage as soon as possible. These are the worst possible sounds that you can hear from a gearbox and are telltale signs that it’s very close to failing altogether. Repairing, or replacing, before it can cause any knock-on effects is key to keeping your bill down.

How to check gearbox oil level

Checking the level of your gearbox oil is a key maintenance tip to ensure that your gearbox is working at optimum levels. The method for carrying this task out is very much like that of the engine oil.

  • Unlike checking engine oil, this check should be made while the engine is running, and has been doing so for long enough to warm the gearbox oil.
  • Park your car on a flat surface, place the handbrake on and open the bonnet.
  • Locate your gear oil dipstick – often near the back of the engine bay – and remove it.
  • Clean the dipstick with a rag, and then reinsert it back into its holster.
  • Remove once again and you shall receive a reading of your oil levels.

Your dipstick should not only have hatchings showing the level that the oil is sitting at, but also ‘hot’ and ‘cold’ lines – the oil should never go above the hot line. If it is low on the reading, then top up using a long-nosed funnel.

Do electric cars have a gearbox?

Anyone who has driven an electric vehicle (EV) will know that the accelerator pedal has a far greater response than that of a traditional internal combustion engine (ICE) car. Whereas an engine needs to work its way up to its optimum power band, an electric car offers instant torque at all levels, negating the need for any gearing. As a result, EVs often only have the single gear, and thus a gearbox is no longer needed.

Get the best price with Scrap Car Comparison

If the gearbox is just one of a number of issues plaguing your car, then it might be time to say goodbye. By selling your car as scrap or salvage with Scrap Car Comparison, you’ll be put through to a team of experts who’ll find a specialist scrap or salvage dealer to buy the car from you, at the very best price available.

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