IF you own an automatic transmission car, this article is not for you. This particular article is for people who drive with three pedals and not two. While auto transmissions do have clutches but they are not of the type we are looking at here.
Drivers who own three-pedal cars will know (or soon know) the feeling of a “baggy”, or slipping clutch. This is a common problem but easily rectifiable by replacement of said component.
Clutches are the link between your powerplant and gearbox. As such, they lead hard lives and barely see any maintenance bar the odd fluid top-up or clutch cable replacement.
A basic clutch consists of a pressure plate, a friction disc and a release bearing. These components allow the clutch to engage or disengage from the flywheel (connected directly to your engine).
Basically, pressing the clutch pedal will apply pressure to the release bearing which in turn will press upon the pressure plate and also release the friction plate from the flywheel. This type of clutch (a single-plate dry clutch) is found in most cars but there are a few different types as well.
A wet clutch is found in high performance cars and is partially submerged in oil. The oil lubricates and also cools the components. Usually if your car’s output exceed 250 lb/ft of torque it will require a wet clutch in order to control clutch temperatures. Generally, this type of clutch also has multiple plates.
A different and new form of clutch is the dual clutch system. This type employs a large clutch for the odd-numbered gears and a smaller clutch for the even-numbered gears. Used in automatic and semi-automatic gearboxes, the two multiplate clutches are the wet-type and is renowned for smooth and seamless gearchanges. This is because the output from the engine is unbroken as one clutch engages while the other is disengaging. Any supercar or hot hatch worth its salt will employ this type of clutch.
The most common problem with clutches is wearing down of the friction plate. Every time the friction plate engages the flywheel, it will need to accelerate to the same speed as the flywheel. Springs in the pressure plate take some of the force and also allows the clutch engagement to be smoother. Over time, the friction material will start getting worn and the springs will also lose their youthful bounce. The pressure plate springs will also be less forceful (or even break off). Usually, most clutches last up to 100,000km before needing attention.
As the friction plate gets thinner, the rate of wear also increases due to its inability to counter heat. Then, a slipping clutch will introduce itself to you by allowing the engine revs to rise without any marked increase in acceleration when you press on the accelerator somewhat vigorously and in the lower gears. A truly worn out clutch will not allow any drive at all. Sometimes, you may also encounter slipping clutches due to a worn-out output shaft seal. This allows oil to contaminate the plate and make it slip.
Another favourite trick of clutches is to rattle when you press the pedal. This means the release bearing (or sometimes called the throw out bearing) is damaged. There have also been cases when the release bearing lever pivot wearing out (classic cars) or the release bearing lever getting bent (accident damage or poor design). Pressure plate springs breaking and damping springs sagging will also result in slipping clutches in the former and jerky engagement in the latter.
There is no remedy for these ailments except wholesale replacement of the parts. However, it is important to go to a reputable dealer or specialist foremen as assembly of any clutch will require a clutch alignment tool. A misaligned clutch will judder on engagement and promote vibration in the chassis and engine.
It is also important not to skip replacement of the output shaft seal otherwise your brand new clutch might quickly become secondhand due to oil leakage.
There are a few ways to increase the lifespan of your clutch. First and foremost is the condition of your clutch master and slave pump (if hydraulic) or the condition of the cable. Hydraulics mean automatic adjustment but also means a half yearly fluid change and/or bleeding of the system. A cable requires none of that but requires manual adjustment once in a while. Neglecting this step will allow your clutch to drag and wear it out prematurely.
Avoid harsh engagement of the clutch (or in racing terms, dumping the clutch) at any time. Smoking tyres may look cool but they wear out a myriad of components, namely your clutch and tyres. This is important especially in first gear when the inertia of the car is highest. Release the clutch smoothly in each gear to lengthen the clutches’ life. Towing a trailer or frequenting uphill resorts will also reduce the lifespan of your clutch. So will “riding” the clutch pedal or resting your foot on the clutch pedal while driving.
The key to prolonging your clutch is regular maintenance and gentle treatment of it. So take the car out and try a few hard accelerations in second or third gear. If your clutch starts acting up, I will see you soon at the shop.