Why do my gears keep grinding?

Any driver knows that feeling and hearing your gears grinding is a very unpleasant sensation and can set alarm bells ringing. There are a few reasons why you might be experiencing grinding gears, and it’s important to identify the cause before serious, long-term damage is done to any of your car’s key components.

A car with manual transmission features an input shaft, output shaft and countershaft. In order for the driver to successfully and smoothly change gear, the shafts need to be going at the same speeds and the clutch needs to fully disengage then re-engage. You will hear a grinding noise from your gears if the clutch isn't completely disengaging from the engine while the gears are rotating or if the shafts are moving at different speeds. Grinding gears can occur if your clutch has gone bad, if your gear synchronisers have worn out, or if your transmission fluid is low, old, dirty or poor quality.

What are the common causes of grinding gears?

Worn, damaged or faulty clutch

Risk level - Medium

What to do - If your car only makes a grinding noise when changing gear, and not at any other point, such as when braking or accelerating, you’re likely dealing with a clutch problem. With a manual car, you’ll feel or hear the grinding noise when you shift into a different gear. You’re hearing this grinding noise because the clutch is not properly disengaging with the engine, preventing you from changing gears smoothly. Your clutch which may need to be replaced or readjusted to resolve this problem.

Transmission Fluid

Risk level - Medium

What to do - Another common cause of grinding gears is low or poor quality transmission fluid. If there isn't enough fluid to lubricate your gear system or the fluid itself is old, dirty, or poor quality, then there won't be enough lubrication. Your car will struggle to change gears, causing a grinding noise, and key components of your gear system may be damaged if you continue to drive with bad or low levels of transmission fluid.

Driver error

Risk level - Low

What to do - A grinding noise does not always signal an imminent problem. The noise can occur when a driver fails to properly engage the clutch. Inexperienced and experienced drivers alike occasionally forget to engage the clutch fully when changing gear. When the driver attempts to move up or down a gear while the clutch is not fully engaged, the car will make a grinding noise.

To avoid this be sure to press down fully on the clutch pedal when changing gears and remember to shift smoothly and softly. Grinding your gears too much or trying to force a gear change could cause long-term damage to your car.

How long should a clutch last for?

There isn’t a set amount of time or mileage that your clutch should last for, as it can depend on both the car and your driving style. Most clutches are designed to last approximately 60,000 miles, however they can remain healthy and in good condition after covering anywhere between 30,000 and 100,000 miles.

There are a range of factors that can affect the lifespan of your clutch:

• Quality of driving – if you do a lot of stop-start driving or fancy yourself a bit of a “boy/girl racer”, i.e. revving your engine excessively and harsh acceleration without climbing up the gears first, this is likely to wear down your clutch more quickly

• Quality of vehicle – the car’s age and the mileage it’s done can affect how often the clutch needs replacing

• Maintenance of your car – regular services and checks to ensure the car is in good health and operating as it should be

Can you drive with grinding gears?

If your gears grind frequently when driving, and it’s not due to driver error, it’s not a good idea to carry on driving your car. The grinding noise you hear is most likely due to a worn or faulty clutch, which will only get worse or more damaged the longer you continue to drive. If you have a bad clutch it's only a matter of time before your car won't be able to drive anywhere, so you need to get it checked out by a mechanic as soon as possible. They will be able to diagnose the issue and may recommend a clutch kit replacement.

How do I stop my gears from grinding?

There are multiple ways to try to resolve grinding gears. The solution could be as simple as topping up your transmission fluid or could involve having to replace one or more parts of the clutch mechanism. If you’re handy with cars you may be able to check and top up your transmission fluid yourself (it might also be a good idea to check for any fluid leaks coming from your car). If you think your transmission fluid could be old or dirty, it might be a good idea to book your car in for a flush and replacement.

How much does it cost to fix grinding gears?

If you think your grinding gears could be a result of insufficient, old or dirty transmission fluid, you can book your car in for a flush and replacement. In the UK this typically costs between £163 - £176.

It is also likely that grinding gears could be a result of a worn, damaged or faulty clutch, which will need to be inspected and possibly replaced by a mechanic. The price of a clutch replacement can range between £300 to £700, and will be at the higher end of that range if your flywheel needs to be changed. From our research, we’ve determined that the average price of a clutch replacement in the UK is £474.