CLUTCH FAULT FINDER

FAULT POSSIBLE CAUSES REMEDYDriven plate sticking on splined Spline damaged during fitting. Remove burrs/Fit new clutch. input shaft. Hub splines/Gearshift damaged. Replace clutch/shaft or both. Hub spline rusted. Clean/grease hub and spline. Worn spline on shaft. Replace shaft.

Clutch plate is too thick. Incorrect plate fitted. Fit correct clutch.

Spigot bearing seized or defective. Defective part not replaced when Replace the spigot bearing. new clutch fitted.

Driven plate bent or buckled. Misalignment during fitting. Fit new clutch. Handling or transit damage. Gearbox allowed to ‘hang’ unsupported during fitting.

Driven plate scored by Release bearing pushing diaphragm Fit new clutch. spring fingers. on to driven plate (overstroking). Possible defective cover assembly or driven plate. Over adjustment of clutch release mechanism.

Driven plate run-out is excessive. Driven plate damaged prior to or Check driven plate is not distorted during fitting. maximum allowance is 1.0mm.

Incorrect cable adjustment. Stretched, wrongly adjusted or Adjust cable to specified setting or incorrect cable fitted. replace with correct part.

Faulty hydraulic system. Defective hydraulic parts, old or air Check hydraulics, replace defective impregnated fluid. parts, bleed system.

Worn cover assembly Release bearing seized/misaligned Replace clutch unit and ensure diaphragm fingers. during fitting Clutch overadjusted. correct adjustment.

Clutch does not disengage correctly. Release bearing clearance too great. Where possible adjust to specified setting.

Insufficient travel on release Self adjusting system not adjusting Check operation and correct or renew. mechanism. or resetting. Check and correct adjustment. Incorrect adjustment of clutch free play. Check fluid level, check for fluid leaks Air in fluid or leak in hydraulic systems. and bleed system. Renew fluid if necessary. Clutch release mechanism worn. Renew defective parts. Diaphragm fingers or release levers Replace defective parts. damaged or bent.

Broken diaphragm spring. Incorrect fitment/adjustment Renew defective parts and check clutch overstroked. adjustment/clutch stop.

Cover assembly drive Tow starting in too low a gear. Renew defective components. strap damaged. Excessive driveline wear. Check engine rotation in relation to clutch cover assembly. Incorrect part fitted. Fit correct parts.

Cover assembly Damaged or misaligned during Fit new clutch unit. flange distorted. fitting fouling dowel pin.

> Drag/NoN-releaSe

FAULT POSSIBLE CAUSES REMEDYUneven wear to driven Worn/grooved flywheel/cover Replace defective parts. plate facing. /dropped plate.

Driven plate facings Faulty oil seal on engine or gearbox. Locate / correct leak, renew clutch. contaminated with oil. Hub/spigot overgreased. Clean all parts, renew clutch. Release bearing losing grease. Clean all parts, renew clutch.

engine or gearbox mountings. Damaged, broken, worn mountings/stabiliser. Replace defective parts.

Clutch plate fitted with wrong Wrong fitment. Fit correct part. friction material.

Worn spigot bearing. Worn/missing bearing, worn spigot shaft. Replace defective parts.

Misalignment of release bearing. Incorrect fitting, worn release mechanism. Replace defective parts.

Clutch linkage stiff/partially seized. Faulty cable/hydraulics, faulty Replace or repair defective parts.

Clutch cover not parrallel Cover incorrectly fitted to flywheel or Renew clutch, ensure correct with flywheel. wrong part fitted. fitment/dowel location.

Broken driven Damaged when fitting. Incorrect Renew clutch. plate linings. driving practice.

FAULT POSSIBLE CAUSES REMEDYClutch is running partly disengaged. Release bearing clearance too tight. Reset adjustment to specified setting. Too much friction in release mechanism. Repair or replace. Slave cylinder not returning. Renew defective parts. Cable binding/partially seized. Renew defective parts.

Clutch plate facings Normal wear life. Renew clutch. worn out. Driver misuse, resting foot on pedal Renew clutch. whilst in motion or riding clutch Sticking release mechanism. Check release mechanism, cable/hydraulic system. Renew defective parts. Clamp load of cover indufficient or Renew clutch. weak spring. Flywheel refaced on wearing Machine cover mounting surface by surface only. same amount. Clutch fitted to worn/grooved flywheel. Machine or replace flywheel. Insufficient free play in release mechanism. Adjust to specified setting.

Clutch facings Excessive use of spline grease Clean off all surfaces and renew clutch. contaminated with during fitting. grease/oil. Oil leakage from gearbox or engine oil seal. Cure oil leak, replace complete clutch. Ensure all parts are clean.

Pressure plate Overheated through prolonged use Fit new clutch. broken into when slipping. segments.

Uneven driven Flywheel face worn/grooved. Renew defective parts, fit new clutch. plate wear.

Broken driven Damaged when fitting. Incorrect Renew clutch. plate linings. driving practice.

Flywheel damaged or out of true. Machining error when refinishing flywheel. Machine or replace flywheel.

> SlIP

> JUDDer

FAULT POSSIBLE CAUSES REMEDYWorn spline in driven plate. Primary gear bush worn, excessive Replace defective parts, reset end float. gear end float.

Distorted/broken Tow starting, excessive transmission Replace defective parts. cover drive strap. wear, wrong part fitted.

Cover assembly pressing distorted. Damage caused fitting compression Replace cover assembly. clips prior to fitting (GM units). Fit compression clips correctly.

FAULT POSSIBLE CAUSES REMEDYDriven plate distorted. Misalignment during fitting. Fit new clutch.

Stiff or erratic clutch Faulty cable/hydraulics, faulty Check/replace cable or hydraulics, release mechanism. release mechanism. renew/repair release mechanism.

oil contaminated Faulty oil seal on engine or gearbox. Locate and correct leak, renew clutch. clutch plate.

FAULT POSSIBLE CAUSES REMEDYWorn or broken Poor driving practice, causing excess ‘load’. Renew clutch. torsion spring/worn driven plate hub.

Driven plate fouling flywheel. Driven plate fitted wrong way round. Renew clutch. Overmachined flywheel. Fit new flywheel/clutch.

Wrong driven plate fitted. Torsion spring not suitable/hub too Fit correct part. high and catching.

Worn driven plate spline. Misalignment of engine to gearbox, Renew driven plate, check spline/primary worn primary gear. gear for wear, ensure correct aligment.

release bearing noise. Faulty/overheated bearing. Renew bearing, adjust free play. Insufficient bearing pre-load. Adjust release mechanism to correct setting. Misaligned bearing. Check alignment and correct. Misaligned engine/gearbox. Check dowels, ensure correct alignment.

Spigot bearing noise. Spigot bearing is worn or unlubricated. Renew parts and lubricate. Worn spigot shaft. Fit new part. Spigot bearing missing. Fit new part.

release mechanism worn or Worn parts not checked, lubricated Renew defective parts, ensure partially seized. or replaced. correct operation.

Primary gear noise. Bush worn in primary gear sleeve, Renew defective parts. Reset end excessive end float. float to correct specification.

Cover assembly noise. Loose/worn components in cover. Renew clutch. Overstroking of release mechanism. Adjust to correct specification.

FAULT POSSIBLE CAUSES REMEDYDriven plate hub Damaged during fitting due to ‘hanging’ Replace driven plate/clutch, ensure centre broken away. of gearbox. correct fitting procedure. Driver abuse of clutch during engagement. Advise driver.

Splines of driven plate Misalignment of engine to gearbox. Replace clutch/spigot shaft, ensure stripped or worn. Loose bellhousing bolts. correct fitting procedure.

> JUDDer

> SNaTCh

> NoISe

> ClUTCh DoeS NoT DrIve

FAULT POSSIBLE CAUSES REMEDYDriven plate spline riding over spigot Incorrect part fitted for application, Fit correct parts, renew any shaft spline. spline too large. damaged components.

Driven plate splines Damaged/badly worn bush on Replace primary bush/sleeve and stripped. primary gear sleeve. renew clutch.

FAULT POSSIBLE CAUSES REMEDYexcessive slip during Driver abuse allowing slip. Renew defective parts. clutch engagement. Incorrect adjustment. Renew defective parts and ensure correct adjustment.

Insufficient cover assembly clamp Normal wear life. Replace clutch. load, weak spring. Cover not replaced last fitment. Replace clutch. Excessive clutch slip. Replace clutch.

Damaged or scored friction surface Flywheel not machined or replaced. Fit new flywheel/clutch. of flywheel.

FAULT POSSIBLE CAUSES REMEDYlack of resistance from clutch pedal. Air/fluid leak in hydraulic systems. Trace fault, renew defective parts. Stretched clutch cable. Renew cable, reset adjustment.

Weak/broken Cover not replaced during last fitment. Renew clutch. diaphragm spring Cover damaged during installation. Renew clutch. in cover assembly. Cover incorrectly fitted. Renew clutch. (Fig. 19).

Since friction clutches are dry clutches, and wear during the slipping phase, i.e., while the rotational speed of the driven plate is being brought up to that of the flywheel, is normal. The basic prerequisite for a long clutch life is ensuring that the

clutch release mechanism is in a perfect working order and that the clutch is not abused while driving. Clutch life may be adversely affected by the following:• Revvinguptheenginewhenstartingoff

or starting off in the wrong gear;

• Stop-and-godrivinginheavytraffic;• Manoeuvringincloseconfines;• Preventingthevehiclefromrollingback

on inclines by slipping the clutch, and failing to use the accelerator pedal to match speeds when downshifting.

NATIONAL AUTO PARTS Willow Road, Lenton, Nottingham NG7 2TA, England. Tel: +44 (0) 115 97 38 100 Fax: +44 (0) 115 97 38 104

Email: info@national-auto.co.uk Web Site: www.national-auto.co.uk

The ServICe lIFe oF ClUTCh FaCINgS

> ClUTCh DoeS NoT DrIve

> PreMaTUre/aBNorMal FaCINg Wear

> SoFT/SPoNgy ClUTCh oPeraTIoN

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