The clutch in your car endures a huge load as every time you use it, whatever power your engine is producing is transmitted through the gear box and diff to change the inertia of over a tonne of car. Obviously the biggest load is applied as you get your car to move off from a stationary position.
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Over the years manufacturers have developed several variances of the automotive clutch but they all consist of at least one plate with a friction surface that gets clamped between machined steel (or similar) plates that are secured to the rotating shaft (usually crankshaft) of the engine. one of these steel drive plates has the ability to be moved away from the others so that the friction plate can then spin freely between the drive plates, allowing for the vehicles transmission to be disconnected from the engine. Originally all systems had a thrust bearing that was pressed against levers or fingers that then pulled the drive plate away from the friction plate. This was done through a series of levers & pivots that were connected to the clutch pedal.
This system of levers was very prone to wear at all pivot points and required frequent adjustment. Before long most vehicles started using cables that gave a more direct transfer of the force require to activate the clutch. The cable was connected directly to the clutch fork, which is a lever that resembles a 2 prong fork and slides the thrust bearing along a shaft to activate the clutch. This saw greatly reduced frequency of adjustment and is still used on some vehicles today, although most now use advanced hydraulic cylinders similar to those used in braking systems. Hydraulic systems are generally self adjusting, and provided that the fluid is changed every 2 years, have proven to be extremely reliable. Many hydraulic systems now have the thrust bearing and slave cylinder built into a single unit, mounted directly to the nose of the gearbox, negating the need of the fork, thus eliminating another pivot (wear) point.
Usually clutch kits are bolted to the flywheel on the rear of the engine, and these days we are seeing an increasing number of what is known as dual mass flywheels. These flywheels consist of 2 metallic sections connected to each other with vulcanised rubber and or springs. The purpose of this is to absorb some of the shock & extreme force applied as the clutch is engaged and generally provide for a quieter & smoother take off & gear changes. The down side of them is the fact that when the clutch does need replacing, the flywheel itself requires replacement as well, where as a solid flywheel will usually only need to have the working face machined so that it is smooth and free from heat induced hard spots, that could cause a clutch shudder.
Commercial vehicles obviously need a much stronger clutch as they move far heavier loads, and this is often achieved by using larger components with heavier springs to apply great clamping forces. Sometimes these are so heavy to push that the vehicle also has booster similar to brake systems to assist the driver to press the pedal down. Another way of achieving the extra clamping force is for the vehicle to be fitted with a multi plate clutch that has several friction plates with drive plate wafers between each of them. This allows for a greater force transfer due to increased surface area within a similar space. The friction plate in commercial vehicles is often made of a harder material as well, to give a longer life to the clutch.
High performance and race cars throw even more complications to the equation due to the fact that they require the extra clamping forces due to higher power being required faster than usual road use driving, but it is also very beneficial if they can remain as light as possible to provide quicker response to a fast revving engine. Usually these have a flywheel that is thinner and lighter than the average car, and the friction plate often consists of small ceramic based friction pads affixed to a steel disc without the spring cushioning centre used in a road going clutch. Often on very high powered competition cars, a 2 or 3 plate multi plate system is used. Vehicles fitted with competition clutches are generally very hard to drive at slow speeds or in traffic situations, as they tend to require a very heavy pedal force to operated and the clutch either on or off, as there is no slippage to take up the drive gradually.
With all these forces placed on a relatively small component, there are many things that can wear and affect the efficiency of your clutch. The friction plate itself will wear out over time & use and this usually shows itself as a slippage where your engine will rev at a faster rate than the vehicle would normally accelerate. This is often accompanied by a burning smell. Maybe your clutch is shuddering or jerking as you take off and change gears and this could be caused by heat damaged components, an oil leak onto the clutch or broken engine mounts. As previously mentioned the clutch is connected to your clutch pedal by way of either mechanical means (cable or linkages) or hydraulic cylinders and if any of these are worn, broken or leaking your clutch has no chance of working as it should. Clutch repairs will often require the removal of the gearbox and with 4 hoists and the necessary lifting equipment, Viva Auto Repairs can do this efficiently and safely, once we have fully diagnose the issues and quoted on the repairs. If your car needs a clutch replacement we can fit a clutch from a wide range, from standard replacement to heavy duty if you regularly tow and even the well renown Extreme competition clutches supplied by Australian Clutch Services, an award winning South Australian business, known for their quality clutch components and great service.