Section 2 Clutch Assembly - Testroete

1 Manual Transmissions & Transaxles Course 3021. Identify the purpose and function of the clutch2. Identify and describe the operation of the following clutchcomponents:a. Clutch discb. Clutch cover assemblyc. Flywheeld. Hydraulic systeme. Release bearings and forkf. Clutch cover assembly3. Identify and describe Clutch service proceduresa. Clutch pedal free travelb. Clutch slippagec. Clutch spin downd. Clutch pedal noise4. Identify and describe Clutch component inspection procedures5. Identify and describe Clutch removal and replacement procedures6. Identify and describe Clutch Assembly procedures7. Describe hydraulic system repair proceduresSection 2 Clutch AssemblyLearning Objectives:Component Testing2 TOYOTA Technical TrainingThe Clutch Assembly interrupts the power flow between the engine and thetransmission when the vehicle is brought to a stop with the engine runningand when shifting gears.

2 The Clutch Assembly consists of the followingcomponents: Clutch disc Flywheel Clutch cover Assembly Clutch release bearing Clutch release forkThe Clutch disc is connected to the input shaft of the transmission,and is located between the flywheel and Clutch cover Assembly . Theflywheel is connected to the engine crankshaft and the Clutch coverassembly is attached to the flywheel. The Clutch release fork forcesthe Clutch release bearing against the diaphragm spring of theclutch cover Assembly ComponentsThe Clutch Assembly contains several majorparts: flywheel, Clutch disc, Clutch coverassembly, Clutch release bearing, and clutchrelease 2 Clutch AssemblyClutchAssemblyTRX ESP Troubleshooting GuideManual Transmissions & Transaxles Course 302 The flywheel is connected to the engines crankshaft.

3 A flywheel isvery similar to a brake rotor in appearance. It is a large metal disc thatstores and releases energy pulses from the crankshaft. It drives theclutch by providing a friction surface for the Clutch disc. In addition,the flywheel provides a mounting surface for the Clutch cover, and alsodissipates flywheel is verysimilar to a brake rotor inappearance. It is a largemetal disc that stores andreleases energy pulses fromthe pilot bearing supports the engine side of the input shaft. The pilotbearing used on Toyota vehicles is a ball bearing located in a bore inthe end of the crankshaft. The pilot bearing only turns when the clutchis Clutch disc is the connecting link between the engine and thetransmission. A Clutch disc provides a large surface area made offriction material on both sides.

4 In the center, a damper assemblyabsorbs torsional facing, or friction material is riveted to the cushion plate on bothsides and is similar to the composition of brake lining. The cushionplate has a wave design that allows the facings to compress when thepressure plate is engaged. This provides a smooth engagement ofengine and BearingClutch DiscComponent Testing4 TOYOTA Technical TrainingClutch DiscThe Clutch disc connectsthe engine and thetransmission providingfor smooth are provided in the Clutch disc facing to eliminate the problemof the Clutch disc adhering to the flywheel and the pressure plate of theclutch cover Assembly . Air is trapped in the grooves when the Clutch isengaged. When the Clutch disc is released, the centrifugal force of theturning disc causes the trapped air to push against the flywheel andpressure plate.

5 This action breaks the adhesion created between theflywheel, Clutch disc facing and pressure GrooveTo eliminate the problem ofthe Clutch disc adhering tothe flywheel and pressureplate, grooves are providedin the Clutch disc ESP Troubleshooting GuideManual Transmissions & Transaxles Course 302 The internal splines of the Clutch hub fit over the external splines ofthe transmission input shaft allowing the Clutch hub to move back andforth smoothly. Most Clutch discs include a damper Assembly toreduce or eliminate torsional vibrations that occur from uneven engineand drivetrain power the engine power cycle, the crankshaft speeds up andslows down during each revolution. The damper removes slight speedfluctuations, which prevent vibration, gear rattle, noise and wear tothe transmission and damper Assembly consists of a hub flange that pivots between thedisc plate, and cover plate.

6 Each of these components have four to sixopenings in which the torsion dampers are located, allowing torque topass from the disc plate and cover plate to the hub flange and hub. Thetorsion dampers absorb the shock of: Clutch engagement, accelerationand deceleration and power pulses from the Hub &DamperAssemblyThe damper reducesor eliminates torsionalvibrations that resultfrom uneven engine anddrivetrain power Hub &Damper AssemblyComponent Testing6 TOYOTA Technical TrainingThe Clutch cover Assembly is bolted to the flywheel and provides thepressure needed to hold the Clutch disc to the flywheel for proper powertransmission. It is important that the Assembly be well balanced andable to radiate the heat generated when the Clutch disc is uses two types of Clutch cover assemblies: Diaphragm spring Diaphragm Spring Turnover (DST)ClutchCover AssemblyThe Clutch cover assemblyis bolted to the flywheeland provides the pressureneeded to hold the clutchdisc to the diaphragm spring is a round, conical shaped spring thatprovides the clamping force against the pressure plate.

7 Pivot ringsare installed on both sides of the diaphragm spring. They serve as apivot point when the release bearing is forced against the diaphragmspring. The pivot stud connects the diaphragm spring to the clutchcover. The retracting springs connect the diaphragm spring and thepressure plate. The straps connect the pressure plate to the clutchcover and do not allow the pressure plate to move out of position. Whenthe release bearing is pushed against the diaphragm spring, the springfolds inward and the pressure plate moves away from the Clutch CoverAssemblyDiaphragm SpringTRX ESP Troubleshooting GuideManual Transmissions & Transaxles Course 302 The Diaphragm Spring Turnover (DST) type of Clutch cover assemblydiffers from the conventional type only in construction. The DST coverdoes not use a separate pivot stud to connect the diaphragm spring tothe cover.

8 The cover is shaped so that the pivot points are part of theclutch cover. Since the retracting springs have been eliminated, thestrap springs are used to disengage the pressure plate from theclutch disc. The diaphragm spring fingers are chrome plated in thearea where the release bearing rides to help eliminate wear and this design, the Clutch cover gives optimum release performanceand is Turnover (DST)The DST cover does not use a separatepivot stud to connect the diaphragm springto the engagement begins when the pressure plate of the Clutch coverand flywheel begin to rub against the Clutch disc. The amount of torquetransferred to the Clutch increases as spring pressure against thepressure plate increases. When the Clutch is engaged, pressure fromthe Clutch cover diaphragm forces the pressure plate against theclutch disc and SpringTurnover (DST)Component Testing8 TOYOTA Technical TrainingThe purpose of the Clutch release bearing is to transfer themovement of the Clutch release fork into the rotating diaphragmspring and Clutch cover to disengage the Clutch disc.

9 There are twomajor types of release bearings used by Toyota. They are: Conventional Self centeringA sealed ball bearing is pressed on the release hub, which is attachedto the release fork. The hub and release bearing slide on thetransmission front bearing retainer sleeve. As the Clutch pedal isdepressed, the release fork moves the hub and release bearing towardthe diaphragm spring of the Clutch cover. When the release bearingcomes in contact with the rotating diaphragm spring, the outer race ofthe bearing will begin to rotate. The outer race is made of a sinteredalloy to reduce wear and noise during contact. The release forkcontinues to move the release bearing into the Clutch cover and thepressure being applied to the Clutch disc is released. On self adjustingclutches, the release bearing is in constant contact with the diaphragmspring.

10 The outer race of the bearing is always rotating with the BearingThe main components ofthe conventional releasebearing are the releasebearing, Clutch releasebearing hub, retaining clipand Clutch release ReleaseBearing & ClutchRelease ForkConventional ReleaseBearingTRX ESP Troubleshooting GuideManual Transmissions & Transaxles Course 302A self centering release bearing is used to prevent noise caused bythe release bearing pressing unevenly on the diaphragm spring. Thisnoise occurs when the centerline between the crankshaft, Clutch coverassembly, transaxle input shaft and release bearing is not the same. Itis used on transaxles because the input shaft does not fit into a pilotbearing in the crankshaft like a transmission input shaft does. Thetransaxle input shaft is supported by bearings in the case.