Why does the clutch slip?

It’s a common problem: you’re driving along a road and it doesn’t feel like your car is quite hitting the speed you’re used to, or it’s taking longer to reach it. Perhaps climbing hills and inclines is harder than usual, or changing gears is tough work.

If you’ve experienced one or more of these, then chances are your clutch is slipping.

But what exactly is a slipping clutch? Why does it happen? And how can you avoid it? To answer that, first we need to understand what role the clutch plays in a car:

Your car’s clutch transfers power from the engine to the wheels, enables you to change gear, and ensures the engine doesn’t stop when your car is stationary. The clutch is made up of three main parts:

• The clutch centre plate
• The pressure plate
• The release bearing

When the pedal is up and your car is moving, the clutch is engaged. This means that the pressure plate is applying a constant force to the clutch centre plate, to keep it touching the flywheel and allowing power to flow from the engine through the transmission.

When you press the clutch pedal, the pressure plate is separated from the clutch centre plate, which in turn disengages the transmission and prevents any transfer of power. This is what allows you to change gear.

When the clutch starts to slip, it means that your clutch centre plate isn’t fully engaging with the pressure plate or flywheel, causing a temporary loss of drive.

There are a few warning signs to look out for that indicate a slipping clutch:

• Sudden loss of momentum or acceleration
• Difficulty accelerating or reaching high speeds
• High engine RPM matched with low vehicle speed
• Difficulty changing gears
• Spongy or sticking clutch pedal
• A burning smell

There are a few reasons that your clutch might be starting to slip, most often due to wear on one or more parts of your clutch.

Your clutch centre plate will naturally accumulate wear over time due to friction, and so if its lining’s thickness is excessively reduced, then it cannot maintain the connection between the engine and the gearbox, causing a slip.

The diaphragm spring provides the force behind the pressure plate, which pushes the clutch centre plate against the flywheel. If the diaphragm spring is worn or damaged, then it may not be able to produce enough force against the pressure plate to properly connect the clutch centre plate and flywheel.

If grease or oil has made its way into your clutch mechanism, then this may be causing a slip. Oil will reduce the friction between your clutch plate and flywheel, making it more difficult for the clutch to work properly.

If your clutch is slipping, then you’ll need to have your clutch inspected by an expert to find the exact problem. Thankfully, at Halfords you can book our Free Clutch Inspection.

One of our trained technicians will assess the operation of your clutch to find the route of the problem, and advise you on next steps.

If there is something wrong, then you can find the right kit for the job at Halfords.com, with our range of car parts. We only use quality, original-spec parts, each with a 2 year or 24,000-mile guarantee, whichever is sooner.

In our clutch kits, you’ll find a clutch centre plate, pressure plate and release bearing, so you’ll have everything you need to replace a slipping clutch.