Analysis of clutch component problems
Contents
1. the races will skid rather than rotate the ball bearings Failure Input Shaft Drive Gear Spline Wear Possible Causes Drive gear spline wear will cause clutch release problems since the driven discs cannot slide freely on the splines This is espe cially true if new driven discs are installed on a worn input shaft Figure 84 Excessive spline wear can be attributed to torsional vibrations This type of wear can be eliminated or lessened by the use of dampened driven discs Spline wear will also occur on the mating driven disc hubs see Figures 61 62 Misalignment can also be a factor in abnormal spline wear It is important to always inspect the input shaft for wear before installing a new clutch If worn it is recommended that a new input shaft be installed to eliminate possible clutch problems later on Failure Galled Input Shaft Possible Causes This failure resulted when the clutch s release sleeve was being side loaded onto the input shaft Figure 85 A worn linkage system and or excessive wear on the release bearing wear pads and release yoke fingers can cause this side loading con dition A galled or rough input shaft in the non splined area will dam age the bushing s of not only the original clutch but also that of the newly installed clutch As a result make sure you replace the input shaft and any worn linkage components to prevent the fail ure from being repeated 31 32 Rel2. failure would be the over torquing of the mounting bolts Doing so can cause the bolts to fracture and eventually separate from the flywheel Combining this scenario with low grade mounting bolts will increase the chances of failure Note Refer to the Eaton Installation Instructions packaged with each clutch to determine the proper mounting bolt torque minimum grade of bolt etc for the specific Eaton Fuller Clutch model you are installing See Torque Specs on page 73 Correct mounting bolt torque 45 ft Ibs on 15 35 ft Ibs on 14 Improperly machined flywheel may leave a tapered edge at raised guide lip of flywheel keeping the clutch from seating properly to the wear surface of flywheel This condition will also affect clutch release and allow slippage Fig 8 Fig 9 Miscellaneous Failure Worn Fingers on Release Yoke Possible Causes The yoke at the left is brand new The yoke at the right is worn excessively and should be replaced This wear can be the result of constant riding of the clutch pedal by the driver and or failure to maintain free play up in the cab see Figures 28 and 29 for the resulting damage that can occur to the release bearing Consequently there will be continual contact between the release yoke fingers and the release bearing wear pads A yoke that is worn excessively may hinder the engagement control of the clutch See Figures 1 5 and 10 for additional photos and de scriptions of
3. the clutch to allow it to continue adjusting CLPISOLOTOOL can be obtained by calling 800 826 HELP 4357 Failure Worn Wear Pad on Release Bearing caused by Running the Truck without Free Pedal Possible Causes When the clutch is properly maintained there should always be free pedal in the cab This will prevent fork contact with the bear ing wear pads and reduce the wear to the pads and the release fork Figure 81 Follow adjustment instructions for correct clutch and linkage adjustment Adjust the clutch before free pedal is lost Apply grease to the yoke fingers to reduce friction when the clutch pedal is stroked 29 30 Miscellaneous Failure Cross Shaft Wear Possible Causes Figure 82 is an example of a worn cross shaft release shaft A worn cross shaft see circle will occur after high mileage and will be accelerated by a lack of lubrication Some problems associat ed with worn cross shafts and or worn linkage systems are e Sporadic changes in the amount of free play in the cab e A binding condition in the linkage system e Erratic engagement of the clutch e Side loading of the release bearing housing As a result a typical complaint might be that it is impossible to maintain proper clutch adjustment To prevent future clutch problems always inspect the linkage system for excessive wear and or binding conditions before installing the new clutch Be Sure to replace any worn components that might hinder
4. 20 Flywheel Flywheel gee O Too Much Runout or Taper on Friction Surface See Figure 14 Driver Notices Clutch engagement is erratic Clutch drags when disengaged Observations The runout is more than engine manufacturer s specifications An abnormal wear pattern is in the area where the disc touches the flywheel Causes The flywheel is damaged or not machined correctly Correction Machine or replace the flywheel according to procedure and specifications of vehicle or engine manufacturer This condition is not covered under Meritor warranty Too Much Runout in Pilot Bearing Bore See Figure 15 Figure 15 Driver Notices Clutch disengagement is erratic and a squeal noise is heard The clutch drags Observations The pilot bearing outer surface is damaged Heat damage is visible Causes Runout of the pilot bearing bore is out of specification Correction Check the runout of the pilot bearing bore Service the flywheel according to the procedure of the vehicle or engine manufacturer Replace the pilot bearing This condition is not covered under Meritor warranty Flywheel Flywheel Housing Figure 16 Too Much Runout on Outer Surface See Figure 16 Driver Notices Clutch is difficult to en gage and disengage Observations The runout is more than engine manufacturer s specifications Causes The engine and the transmission are not correctly aligned Correction Replace the flywh
5. BEARING RETAINER CAP Dimension A based on SAE standards is 8 657 219 9 mm nominal and should not be greater than 8 71 221 5 mm Ref 1990 S A E handbook 4 36 106 Figure 3 Clutch Cover Intermediate Plate Failure Yoke Fingers Rubbing into Clutch Cover Possible Causes Figures 4 5 show the damage that results when the release yoke contacts the clutch cover More specifically the fingers have be come pinched between the clutch cover and release bearing re sulting in one or more of the following e A broken cracked release bearing housing not shown e Damage to the clutch cover See arrows Figure 4 e Wear to the backside of the yoke fingers See arrows in Figure 5 top yoke e Broken yoke finger s see arrow in Figure 5 bottom yoke Some causes of the above failure are e Linkage system broke allowing the loose yoke to con tact cover e Linkage system was improperly reinstalled example forgetting to reinstall the cotter key allowing the clevis pin to come out e Adjusting the clutch with the linkage instead of internal ly using the adjusting ring e Rotating the ring the wrong direction counterclockwise instead of clockwise when adjusting for clutch wear Note The above conditions may be preceded by a noise com plaint Failure Cracked Broken Clutch Cover Possible Causes Referring to the arrow in Figure 6 this brand new clutch Easy Pedal 1402 D was damaged dur
6. ake in front of a worn rough transmission bearing retainer cap e Clutch brake is simply worn out Note A worn clutch brake should be replaced Be sure to always check the transmission bearing retainer cap for any wear and replace if necessary See Figure 3 Clutch Brake Burnt see Figure 79 Driver Notices The transmission is hard to shift into first or reverse gears The clutch may drag Observations Clutch brake is heavily burnt Causes The driver uses the clutch brake when the vehicle is moving A worn or damaged pilot bearing may cause the clutch to drag Correction Replace the clutch brake Inspect the transmission input bearing retainer and replace if required Inspect the pilot bearing and the flywheel and replace if necessary Make sure the driver uses the clutch brake correctly This condition is not covered under warranty Broken Tabs See Figure 80 Driver Notices The transmission is hard to shift into first and reverse gears Alsoa noise may be heard when the clutch is operated Observations Clutch brake tabs are broken Causes The driver uses the clutch brake when the vehicle is moving Correction Replace the clutch brake Inspect the transmission input bearing retainer and replace if required Make sure the driver uses the clutch brake correctly This condition is not covered under warranty Figure80 27 28 Solo Clutch Failure Solo Cam Tab Broken Off Possible Cau
7. clutch operation Also remember to lubricate the linkage pivot points Failure Seized Dry Pilot Bearing Possible Causes Once removed from the flywheel a failed pilot bearing can be identified by one or more of the following conditions e The bearing is dry it is difficult to turn rough or com pletely seized Any condition which causes a dry bear ing will have been accompanied by a noise complaint while it was in the vehicle e Adamaged ball bearing cage See arrow in Figure 83 e A step is worn into the inner race The step is caused when the input shaft spins within the inner race a direct result of the seized pilot bearing e The seal is missing and or damaged because of exces sive heat generated by the dry bearing A typical complaint associated with a failed pilot bearing other than noise is poor release Poor release can be the result of one or more of the following conditions e The outer race of the bearing fits too tightly in the fly wheel e The inner race of the bearing fits too tightly on the input Shaft Fig 83 Miscellaneous Fig 85 e A seized or rough pilot bearing will allow the input shaft to continue rotating even when the clutch is completely disengaged As a result the clutch brake can become damaged and eventually fail see Figure 73 of Worn Clutch Brake e If the bearing fits too loose the end of the input shaft won t be properly fitted Also if the fit is loose
8. ease Fork Wear Is Not Even on Tips See Figure 75 Figure 75 Driver Notices The clutch pedal is hard to push Observations Wear is very different on each tip The ends of the tip are polished The cross shaft and the cross shaft bush ings are worn or damaged Causes The capscrews that fasten the release fork to the cross shaft were too tight or not tightened evenly The cross shaft may be damaged The bushings were not lubricated Correction Replace the release fork Inspect the cross shaft and the bushings and replace if required Make sure the bushings are lubricated at the correct intervals This condition is not covered under warranty Release Fork Cross Shaft Release Fork Cross Shaft Figure 77 Seized aa See Figure 77 Driver Notices The clutch pedal is hard to push and does not return Observations The cross shaft and the bushings are worn or damaged Causes The cross shaft bushings were not lubricated at the specified intervals or with the correct grease dia aS Te l Correction Replace the cross shaft and the FORK DOES bushings Lubricate the bushings at NOT MOVE the specified intervals with the correct grease This condition is not covered under warranty Wear Is Not Even See Figure 78 Driver Notices The clutch pedal is hard to push down The clutch may drag or not disengage Observations Wear is different on either side of the shaft Driver Notices There is a rattle n
9. eel housing Check the engine to transmission alignment This condition is not covered under Meritor warranty 21 22 Clutch Cover Intermediate Plate Clutch Cover Intermediate Plate Failures Failure Yoke Bridge Rubbing into Cover Fig 1 Possible Causes The arrows in Figures 1 and 2 show the areas of contact between the release yoke bridge and the clutch cover Overstroking of the yoke in an attempt to obtain the required 1 2 1 clutch brake Squeeze is a typical cause of this failure The reason that normal clutch brake squeeze cannot be obtained may be due to one or more of the following situations e Worn clutch brake e Broken or missing clutch brake e Worn or incorrect transmission bearing retainer cap refer to Figure 3 e Excessive wear on release bearing wearing pads and or the fingers of the yoke refer to Figure 1 e Improper set up of the linkage system Consult your OEM service manual e Incorrect yoke installed Note The clutch cover can be reused if the above items are cor rected a new yoke is installed and there are no broken or cracked parts on the cover The above failure is typically preceded by anoise complaint and or vibrating clutch pedal at the point where the clutch pedal is fully depressed De pending upon the amount of wear at the bearing cap and or yoke fingers wear pads it may be possible to adjust the linkage to eliminate the noise complaint TRANSMISSION
10. ing transmission installation More specifically the release yoke fingers were elevated to the straight out position and were allowed to jam into the clutch cover Subsequent damage might be a broken finger s Figure 5 or bent release yoke cross shafts As a result it is important that these parts be inspected for damage and replaced if damaged before installing a new clutch Failure Broken Retainer Assembly Possible Causes Figure 7 shows what can happen when the levers break through the retainer s nose The primary cause of this failure is allowing the transmission to hang unsupported in the driven disc during transmission installation 23 24 Clutch Cover Intermediate Plate Failure Clutch Cover Detached from Flywheel Possible Causes The broken mounting bolts show in Figure 8 are the direct result of insufficient torquing of these 8 bolts to the flywheel More specifically these bolts were loose enough to allow the clutch cover to hammer back and forth against each bolt until they broke Also the 8 mounting bolt holes in the clutch cover were egg shaped as a result of the constant hammering Additional damage occurred to both the clutch cover and the re lease yoke as a result of their interference with each other refer to the arrows in Figures 9 and 10 It is worth noting that this ser vice clutch had accumulated 50 000 miles before it failed Another potential cause of the above
11. oise coming from the area of the clutch Light pressure on the clutch pedal makes the noise go away Figure 78 Observations Excessive clearance between the cross shaft and the cross shaft bushings Radial movement is present Causes The cross shaft bushings were not lubricated at the specified intervals or with the correct grease Correction Replace the cross shaft and the bushings Lubricate the bushings at the specified intervals with the correct grease This condition is not covered under warranty 33
12. rease with E P additives 325 degree operating temperature Apply ample lube and let it flow out of the opening from the bearing housing Apply additional lube onto the transmission shaft to ensure the bushing will have proper lube Apply lube to the tips of the release yoke See Fig 85 on page 31 e Misalignment of input shaft can cause a side load on bushing which will pull it out e Worn cross shaft bushings will allow the cross shaft to pull back unevenly resulting in a side load condition on the bushing causing it to come out Solo Clutch Fig 79 t VAR YAN i DRS Failure Solo Cam Tab Spring Broken Solo Stops Adjusting Possible Causes e There is an immediate loss of free pedal in the cab e The release bearing is touching yoke and too far from transmission Consult troubleshooting guides for help There will be no tension pulling the cam wear indicator toward replace Troubleshooting guides CLTS 1296 Medium Duty and CLTS 1295 Heavy Du ty Failure Solo Adjustment Rings Contaminat ed Solo Stops Adjusting Possible Causes lf there is excessive amounts of contamination allowed into the clutch housing the Solo may stop adjusting and there will be a loss of free pedal in the cab see Figure 80 Check to see if the inspection cover has been removed In severe dust applications it may be necessary to seal all openings in the clutch housing Eaton has created a tool that may help free up
13. release yoke failures 25 26 Adjusting Mechanism and Clutch Brake Ei Failure Bent Broken Kwik Adjust Mecha 97 nism Possible Causes Referring to Figure 71 the kwik adjust mechanism at the right is a normal and properly functioning adjuster while the one at the left has been damaged as evidenced by the bent mounting bracket The one pictured in Figure 72 also has a bent mounting bracket in addition to some broken gear teeth see arrow Some causes of these failures can be e Forgetting to depress the kwik adjuster while attempt ing to rotate the gear Fig 72 e Only partially depressing the mechanism while attempt ing to rotate the gear e Attempting to rotate the gear while the clutch pedal is in the up position clutch is not released Failure Worn Clutch Brake Fig 73 Possible Causes As shown in Figure 73 the facing material on this clutch brake is completely worn away Figure 74 shows a clutch brake that is partially worn See arrows Both types of failures can be attrib uted to one or more of the following e A clutch that is releasing poorly for corrective action see the troubleshooting section titled Poor Release thus making it more difficult for the clutch brake to stop the transmission input shaft e Hitting or engaging the clutch brake when the trans mission is in gear and the vehicle is in motion e The clutch brake was set too high e Installing the new clutch br
14. ses In Figure 75 the tab was broken when someone was attempting to change the adjustment of the clutch The clutch cannot break the tab Many times the tab is broken to change the bearing to clutch brake distance when it is in the proper position Do not at tempt to change the clutch adjustment before measuring the re lease bearing to clutch brake distance Note Consult the troubleshooting guides for help If the release bearing is set to the correct dimension do not attempt to use the cam tab to change the adjustment to the wrong di mension and break off the tab Troubleshooting guides CLTS 1296 Medium Duty and CLTS 1295 Heavy Duty Failure Solo Over Adjust Problem Possible Causes Measure the distance between the release bearing and clutch brake Correct distance should be between 490 and 560 with the pedal up Figure 76 If the bearing is close to the clutch brake and the clutch has not been removed and re installed on the fly wheel then an overadjust might have occurred Consult trouble Shooting guides for help Follow the fault tree for proper diagnosis and correction Failure Bushing Wear and Bushing Failure Possible Causes As shown in Figures 77 and 78 incorrect lube or not enough lube can cause a failure External contamination will also cause wear to the bushing The transmission input shaft may be rough and require replacement Use approved compatible lube High qual ity N L G 1 2 or 8 lithium soap g
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