Clutches

If you are finding it difficult to get your car into gear or the revs are going up but the vehicle is not accelerating, this may indicate that you need a new clutch. The clutch makes and breaks the drive between engine & gearbox. There are four parts to a clutch operation, these are as follows:
The flywheel, the friction disc, the pressure plate and the release bearing
In most cases you only need the clutch kit replaced, the flywheel is normally ok.

Description of a Clutch

A clutch is a mechanical device which provides for the transmission of power (and therefore usually motion) from one component (the driving member) to another (the driven member). The opposite component of the clutch is the brake.

Clutches are used whenever the ability to limit the transmission of power or motion needs to be controlled either in amount or over time (e.g. electric screwdrivers limit how much torque is transmitted through use of a clutch; clutches control whether automobiles transmit engine power to the wheels).
In the simplest application clutches are employed in devices which have two rotating shafts. In these devices one shaft is typically attached to a motor or other power unit (the driving member) while the other shaft (the driven member) provides output power for work to be done. In a drill for instance, one shaft is driven by a motor and the other drives a drill chuck. The clutch connects the two shafts so that they may be locked together and spin at the same speed (engaged), locked together but spinning at different speeds (slipping), or unlocked and spinning at different speeds (disengaged).

Dual Mass Flywheel (DMF)

Modern engines can be driven at extremely low rpms. The trend is toward ever increasing engine torques. Wind-tunnel-optimized bodies are creating less wind noise. New calculation methods are helping reduce vehicle weights and weight-saving concepts are boosting engine efficiency as well. The addition of a fifth or a sixth gear can also reduce fuel consumption. Thinner oils are making precise shifting easier. In short: The sources of noise are increasing and natural damping is decreasing.

What has remained is the principle of the internal combustion engine whose cyclical combustion processes excite torsional vibrations in the drive train – the unpleasant consequences of which are gear rattles and body booms. Drivers who are accustomed to increased comfort no longer accept such background noises. The job of the clutch is now more important than ever – in addition to engaging and disengaging, it must effectively insulate the engine’s vibrations.

Physically, this is easy to solve: The mass moment of inertia of the transmission must be increased without increasing the mass to be shifted. This dampens the engine’s torsional vibrations and brings about the desired comfort level. The process reduces load on the transmission at the same time.

It’s all in the name
LUK was the first manufacturer in Europe to develop and sell a dual-mass flywheel in large-scale standard production that was able to realize this physical principle. The name says it all: The mass of the conventional flywheel was simply split in two. One part continues to belong to the engine’s mass moment of inertia, while the other part now increases the mass moment of inertia of the transmission. The two decoupled masses are linked by a spring/damping system.

One clutch disc, without a torsion damper, between the secondary mass and the transmission handles the engaging and disengaging functions. A favorable side effect is that the transmission is easier to shift because of the low mass to be synchronized, and there is less synchronization wear.