How can I tell if my car's clutch is slipping, and what should I do?

As a component of the vehicle subject to wear, the clutch in cars with a manual gearbox requires a series of care if you don’t want to visit the workshop prematurely and, above all, face a high expense to fix the possible problem. This is because the lifespan of the clutch, which acts as the “link” between the engine and the gearbox to transmit power to the wheels, depends greatly on how the vehicle is used and, to some extent, also on the driver’s “skill” in day-to-day driving, so as not to subject it to excessive wear.

To give you an idea: a clutch in a conventional car that is well “driven” can last well over 300,000 km without problems. But simply subjecting the clutch to a serious overheating, for example by abusing its slipping when starting off on a steep ramp, can make the clutch of a new car say “this is as far as we go” much sooner than expected.

How can I tell if my car’s clutch is slipping?

To answer this question, it helps to understand the basic operating principle of the clutch. This component engages and disengages the transmission from the engine so that you can change gear and, once a gear is selected, continue transmitting power to the wheels.

To do this, the clutch has friction discs, the friction linings. When you depress the clutch pedal, we disengage the clutch discs from the flywheel and the transmission of power to the wheels is interrupted. Once the gear is selected, we release the pedal, and the discs come back into contact with the flywheel, transmitting power to the wheels again.

Knowing this, it’s easy to understand that if the discs are worn, they will not have the capacity to transmit power, and then the clutch literally slips. But be careful, because you can also make a new clutch with perfectly good friction linings slip if you don’t have a light touch on the accelerator and the clutch pedal and don’t coordinate the action of accelerating and releasing the pedal, or if you accelerate too abruptly.

When the clutch discs cannot transmit power to the transmission, either because the friction lining they are made of is worn, or because we are subjecting the clutch to excessive stress it cannot handle, the clutch “slips”.

If the clutch discs are starting to wear, you will notice it because when accelerating in higher gears, for example from fourth gear onwards, the engine will rev up but the car will not gain speed as it should, or it will do so in jerks. This is the time to take the car to the workshop for an inspection, before greater disc wear can cause bigger failures.

In a situation of excessive stress, such as the one mentioned above when accelerating too much with the clutch still pressed when pulling away in first gear on a steep ramp, the clutch can slip even if it is new. In these cases, a clear symptom is a strong, distinctive burning smell, and smoke may even appear from the engine bay. This situation is the one that subjects the clutch to the most wear, and it also suffers more during manoeuvres, the more so the greater the load or weight you have to pull, especially if you need to tow a caravan or a trailer.

A one-off clutch slip, in which that burning smell or smoke caused by excessive friction appears, will put the discs under greater wear, but this does not necessarily mean you have to take the car to the workshop. You will have to, however, as we mentioned at the beginning, if you notice that in higher gears the car does not gain speed while the engine revs up, or that the car struggles to start moving from a standstill when you release the pedal.

Other clutch problems

Other possible problems that may arise related to the clutch are the following:

• If the pedal stays down and does not return to its position, it may be due to a fault in the return spring, a loss of hydraulic fluid in the clutch slave cylinder, or a fault in the pressure plate.
• If the clutch does not slip but the car jerks and shudders when you release the pedal and start moving, the cause may be a warped clutch disc, which could be caused by overheating, for example from excessive slipping.
• If the pedal loses feel and becomes very soft, the fault is most likely in the clutch slave cylinder, which is responsible for engaging and disengaging the disc through the hydraulic system.
• Conversely, if the pedal is excessively hard, the disc will struggle to disengage and changing gear will be harder than normal, because it is worn or because the clutch control needs adjusting to “tension” it.