Valeoscope Commercial Vehicles Clutch 2020

Diagnosis Lack of smoothness

3.3 Lack of smoothness Rough clutch engagement

3.3.1 Judder caused by shiny spots on the facing

10. Friction marks on the retainer plates Clutch inspection ●● Friction marks on flywheel (at inner diameter or on bolt holes). ●● Friction marks on damper hub. ●● Burned facings. Vehicle behavior ●● Noise in clutch. ●● Insufficient torque capacity (vehicle stops).

11. Broken disc

●● Facing material quality: depending on facing quality, (organic or cerametallic) torque transfer may be more or less sudden. ●● Damaged clutch linkage Reasons due to the clutch ●● Grease on facings: Oil leakage Over-greasing (tube-guide, splines…) Contaminant on facings (during storage or during handling…) Substance on friction surfaces of facings (anticorrosion, cleaning substance) ●● Geometric defects of parts: Clutch disc: deformation, run out Cover assembly (Pressure plate parallelism, finger tips run out) Release bearing (Wrong contact) ●● Unsuitable type of facing:

Parts inspection ●● The facings surface have 2 different types of aspects (shiny, glazed spots and rough, dark spots). ●● Glazed mainly happens to the contact area of the cushion disc on the facing. Vehicle behavior ●● The vehicle shuffles when it starts up.

Disc broken

Clutch inspection The disc is broken at the cushion pad. Vehicle behavior ●● Metallic noise in clutch. ●● The clutch cannot be released. ●● No torque transmission (vehicle cannot move). Reasons ●● Disc damaged during assembly of gearbox (gearbox hang on hub). ●● Gearbox is mis-aligned after mounting. ●● Abnormal axial vibrations from the engine crankshaft. Diagnosis ò ò The damper can rotate freely as it is completely disconnected from facings. Attention Ɂ Ɂ The gearbox must be assembled smoothly. Advice   Use appropriate tool to assemble the gearbox, (example: support with height adjustment).  Check the injection and the axial clearance of the crankshaft. 12. Diaphragm radial breakage ª ª Refer to chapter 3.2 13. Dust or pieces of the facing between the cover and the pressure plate ª ª Refer to chapter 3.1

Cerametallic instead of organic Organic instead of cerametallic

Friction marks on the retainer plate

Reasons ●● Clutch disc mounted on the wrong side ●● Wrong part number, wrong disc. Diagnosis

Shiny spots on the facing

Reasons ●● This uncomfortable behavior happens when the clutch slips. ●● Facings are not suitable for the working conditions of the clutch. Diagnosis ò ò Some types of facings become glazed when the clutch frequently works under non severe conditions. ò ò The friction coefficient becomes unstable. ò ò The variations of friction coefficient make it difficult to operate the vehicle precisely (both in forward and in backward operations), especially with towing vehicle. This phenomenon occurs when thermal stress is rather low (long haul vehicle). Attention Ɂ Ɂ Avoid to fit repaired or adaptable clutch discs. Advice   Use Valeo clutch discs as they are fitted with performing facings for optimal performance.

ò ò The gearbox side was fitted on the flywheel side. ò ò The clutch disc thickness is not compatible (with flywheel or cover assembly). ò ò By visual inspection through the housing holes, it is possible to see that the clutch disc is still rotating in declutching position. Attention Ɂ Ɂ Check the mounting side. Ɂ Ɂ In general the damper is on cover assembly side (unless there is other specification). Advice   Make sure that the part numbers match with vehicle type (engine, gearbox…).

44

45