When To Change The Clutch Plate On A Bike

“Clutch is used to engage and disengage the engine from transmission while shifting the gears or while to run the engine at idle speed (gearless vehicles). A clutch is a flexible or releasable coupling which connects the adjacent ends of two coaxial shafts. Out of these two shafts, one shaft is crank shaft of an engine and another is an input shaft of a gear box.

It is said to be engaged or in, when the shafts are coupled and disengaged or out, when they are released. We in fact disengage the clutch when we press the clutch lever, otherwise it always remains in engaged position. All of us know that most of the bikes use wet multi plate type clutch to transmit the torque and power.

The use of multi plates is almost universal because there not as much of room is available in bikes to design the single plate clutch. So as a final point, designers uniformly share out the torque and power transmission between numbers of plate instead of single plate. Designers also foretell the life of clutch at the time of designing. Life of the clutch solely depends on frequency and handling of its exercise. Let us have brief outlook about the multi plate clutch assembly. Multi plate clutch assembly consists following components:

  • Clutch Housing
  • Clutch Boss
  • Clutch Springs
  • Clutch Plates (Friction Plates)
  • Pressure Plates
  • Bearings
  • Bushes
  • Oil Seals

Out of above listed parts, commonly we have to replace the clutch plates and oil seals. Other components survive for very long time. Worker or service supervisor suggests us to replace the clutch plates and we blindly accept his proposal as genuineness. Many of you have also faced this procedure at service stations. Likewise, many a times we could have saved our money. Therefore, let us discuss when we really need to replace the clutch plates in our bikes.

Clutch Slips While in Engagement

Clutch slip is the most objectionable fault arises during ride. In clutch slip, friction between clutch plates and pressure plates diminish somehow. Slip causes the loss of torque and power. You can feel it by twisting the throttle hard but not getting enough power at rear wheel.

Possible Causes and Remedies

It is advisable to first check the adjustment of clutch wire with lever (engine casing). If the wire is over stretched, it results in poor engagement of clutch. It the wire is under stretched, it results in poor disengagement of the clutch. Both these practices are harmful to the friction surfaces of clutch plates.

So, it is better to get acceptable tension in clutch wire as soon as you feel the slip. This also adjusts the free clutch lever play (Free play is the initial small distance of lever up to which the clutch remains inoperative). If you let go this fault, it leads to worn out clutch facing after few weeks and you have to replace the clutch plates as a result.

Another possible reason for clutch slip is weak or broken clutch springs. Clutch springs maintain the engagement of clutch plates and pressure plates. These springs drop their stiffness after long time. So, if you are having this fault in your old bike, just replace the springs, not the clutch plates.

Clutch Drag or Burn

Contradictory to clutch slip, friction between clutch plates and pressure plates increases than the required. You can feel this as a difficulty in disengagement of the clutch. Disengagement becomes sticky because of melted friction surfaces. In excess cases, friction surfaces start burning because of overheating.

Possible Causes and Remedies

The very fundamental source of this fault is lack of lubricating oil. Friction between clutch plates and pressure plate increases because of less lubrication and so as the heat. High thermal stresses in plates increase the propagation of cracks on clutch plates and warping of pressure plates. It also tries to seize the clutch plates on the splined clutch shaft.

These all factors lead to the spongy and partly disengagement of clutch. Because of incomplete disengagement, clutch plates and pressure plates always remain in contact generating more and more heat. This becomes a cyclic process and finally at critical temperature, clutch starts burning.

But before a complete burn, the heated friction surface generates typical odour which you can use as a sign to save the clutch. Clutch drag is possible even if your bike is sufficiently topped up with lubricating oil. This happens when the rider is used to shift the gears by partly or without operating the clutch. So, the best possible remedy for clutch drag is to check the level of lubricating oil frequently.

Clutch Judder

It is due to offensive engagement of the clutch. Most of the drivers take it as a power of their machines. If the forward jumping of the bike becomes habitual then you have to think it as a clutch judder. You can feel the judder as an unsmooth engagement with vibration that causes the vehicle to suddenly jump forward. It is not at all result of worn out clutch plates. So don’t change the clutch plates on the spot if somebody suggests you as remedy of clutch judder.

Possible Causes and Remedies

Clutch judder is the result of misalignments or under tightened blots. Misalignment could be possible between plates, bearings and shafts, locks and pressure plates, spring seats and housing. Loose housing bolts, loose housing on flywheel, worn out shaft splines can also produce clutch judder. Sometimes engagement becomes jumpy because of distorted clutch plates also. In that case you don’t have any other options, change the clutch plates.

Clutch Rattle and Knock

Clutch rattle and knock are kind of noise during engine idling and operating conditions respectively. You have to improve your examination skills to draw out the clutch rattle and knocking noise from overall vehicle noise.

Possible Causes and Remedies

Both the undesirable noises are produced from worn out parts. These parts are worn bearings, worn clutch plates, worn out splines of shafts or plates. Here, worn out plates doesn’t mean the friction surfaces. Many times, it happens that friction surfaces remain as it is, but internal or external metal splines got worn out early.

This cause little free movement of plates over the shafts and produces knocking noise at the time of engagement or disengagement. Same thing happens to the shaft bearings which produces rattle noise when engine runs idle. You can also replace these parts from secondary market if friction surfaces are still serviceable. That reduces the cost.

Each of the above listed fault results in worn out friction surfaces and you have to change the clutch plates. But you can save your money by identifying the fault in initial stage. I hope this will be useful to you all in future. Waiting for your valuable comments.”

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