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A clutch is an integral component of a vehicle’s transmission system, serving to connect or disconnect its engine from other parts of its transmission.
A clutch is comprised of several parts, including a flywheel, pressure plate, disc and release bearing. The flywheel attaches directly to the crankshaft of your engine; center splines on the pressure plate secure it to input shaft; disc clamped between these members – these four elements form its structure.
Flywheel
A flywheel, also referred to as a ring gear, is an integral component of the clutch system, used to smooth over uneven crankshaft rotation and transfer torque from engine to transmission.
The engine’s flywheel serves dual roles; it both balances and dampens vibrations that occur while it runs, as well as being connected directly to its crankshaft for easy transmission of power. As an important component, its purpose should also be considered when considering weight reduction efforts for vehicles with transmission.
One mass flywheel is ideal for most vehicles, while dual mass flywheels are made for high performance applications with lighter and stronger clutch disks – these kits can be found for Corvette, Porsche and BMW cars.
Dual mass flywheels may be more costly than their single piece counterparts, but their investment pays dividends when it comes to power delivery and performance. As their friction surfaces wear down more rapidly than normal flywheels, it is vital that when worn they be replaced as soon as possible.
Flywheels may become overheated and damaged from repeated exposure to extreme temperatures, leading to overheating and damage. Inspection should take place during clutch replacement for cracks, hard spots and grooves.
Warped flywheels may also produce a burning smell and chatter sound when releasing clutches, often due to being warped themselves.
Pressure Plate
The pressure plate is an integral component of your manual transmission’s clutch assembly. Constructed from heavy metal, its springs and lever apply pressure against the primary clutch disc while you engage or disengage gears, keeping it securely against the flywheel.
Power from your engine passes through an engaged clutch to your transmission or gearbox system, driveshafts, and ultimately wheels. However, this process places a considerable amount of strain and friction on the pressure plate that could eventually wear away its surface over time.
Clutch pressure plates come in either spring- or diaphragm-type configurations. Spring clutches are most often seen in production cars; however, older V-8 domestic cars, trucks, and pure drag racers may utilize diaphragm clutches instead.
Diaphragm pressure plates employ a cast iron pressure ring that applies pressure from a diaphragm spring to the clutch disc. When depressing the clutch pedal, this pressure ring compresses this disc into the flywheel and forces its thrust bearing to release its load.
When the clutch is released, this thrust bearing reengages with its diaphragm spring and returns power transmission. For maximum performance clutching power transferability some models employ Long or Borg and Beck pressure plates which include centrifugal weights to add clamping force as engine revs increase.
No matter its pressure plate design, clutches are complex machines requiring careful assembly. If parts in your clutch aren’t balanced evenly then its components may become unstable and likely fail; this is particularly likely if driving on rough roads or shifting through high gears has compromised it.
Disc
The clutch is a system designed to connect an engine to its transmission. Additionally, it serves as a protection for the drivetrain when mishandled clutch components are misused or handled incorrectly. Components of a clutch include its flywheel, pressure plate, clutch disc and throw-out bearing.
The disc is an integral component of clutch assembly, controlling how and when the clutch engages or disengages. Made of friction material to provide frictional forces between clutch and flywheel to help regulate rotational speed of car.
Clutch discs can be constructed out of both organic and metallic materials, though ceramic or metallic compounds like sintered iron and bronze tend to provide superior performance and longevity.
High-performance discs often feature springs encasing their center to help dampen engine vibrations and initial engagement shock, as well as any engine vibrations arising during use. Unfortunately, however, such features are seldom found on street vehicles due to increased risks associated with failure.
Dependent upon their purpose, clutch discs may consist of either one or multiple discs. High-performance applications often utilize two or three discs that increase surface area and grip without increasing pressure.
Puck-style discs are often chosen for performance applications due to their higher coefficient of friction, yet aren’t recommended as street discs because they lack smooth engagement capabilities like OEM ones do.
Diaphragm-type pressure plates are the go-to choice in street applications, featuring a sheet metal cover, long springs, and an integral metal pressure ring which serves as the friction surface for clutch discs and release bearings. Some diaphragm springs also have semi-centrifugal weights attached that increase clamping force with engine revolutions increases.
Release Bearing
The release bearing, commonly referred to as a throw-out bearing, is an essential element of your clutch system. Situated between the pressure plate and clutch fork, this bearing helps disengage your car’s clutch when you press on its pedal.
The clutch assembly comprises three main parts: flywheel, pressure plate and disc. This assembly connects directly with both engine and transmission via linkage and allows drivers to change gears with complete control over their vehicle.
To make a clutch work, the pressure plate must be attached to the flywheel and exerting force onto the clutch disc. Pressing down on the clutch pedal causes this force to clamp down onto the disc, transferring power from engine to transmission and vice versa.
After this step is completed, the clutch fork pushes the release bearing against the pressure plate’s springs to disengage the clutch. This process is made possible via cable-type connection which eliminates mechanical links and pivot balls typically found on traditional clutches.
Release bearings also play an integral role in evenly dispersing pressure across the clutch plate, helping reduce vibration and noise in the clutch pedal. When they wear out, you may hear rattling or grinding noises when pressing your clutch pedal.
If you hear these sounds when pressing the clutch pedal, it may be time to replace your release bearing. Though small in size, release bearings have a significant effect on overall vehicle performance and it’s essential they be replaced as soon as possible.
Faulty release bearings can create numerous issues for your vehicle, including clutch drag – wherein the clutch remains engaged when shifting gears – if this issue remains unattended to, leading to more severe complications that require professional diagnostic and repair work.
Fork
Forks are integral components of any clutch, collaborating with other components to ensure smooth operation of its pedal. When activated by pressing on its clutch pedal, forks move throw-out bearings on input shafts which, in turn, force diaphragm springs to disengage clutch plates as per clutch pedal pressurisation.
Clutch forks are made of hardened steel and must be capable of withstanding extreme pressure – often over 1500 pounds – without showing signs of wear and tear. Therefore, it’s extremely important that any problems with your clutch fork be rectified immediately.
As time passes, your clutch fork may wear away at its pivot ball and contact points with the release bearing, and could crack or snap if not properly maintained and lubricated.
An improper fork can create numerous issues, from difficulty changing gears and burning clutches, to making the clutch pedal feel heavy or stiff.
If the clutch fork cannot fully disengage when you press your clutch pedal, this could result in burnt clutch plates and damage to either the flywheel or pressure plate as well as vibrations traveling back through your clutch pedal. If this occurs, vibrations may also travel back up through it causing discomfort to those using it.
O’Reilly Auto Parts provides replacement clutch forks to help quickly resolve clutch problems at a fraction of the cost of purchasing an entirely new clutch system. We carry an assortment of forks designed to address clutch problems quickly and conveniently as well as many other clutch parts to help your car remain in top condition.