Clutch Disc Loss of Drive

Burst clutch disc/no transmitted power.

    • The clutch was engaged while coasting downhill causing the facings to burst through extreme shock.
    • Gear being shifted down when the vehicle engine is revving lower than the transmission ratios, resulting in excessive RPM at the driveline end. This is beyond the capacity of the burst strength specifications of the friction material.
    • Lack of free travel caused by faulty clutch slave cylinder or air over hydraulic system (common in Japanese truck applications). With a new clutch kit installed keeping in mind the diaphragm tips/release lever tips are further down due to the thickness of the new clutch disc. The slave cylinder piston will now be operating further towards the end of the cylinder where it has not worked for some time, depending on adjustment and travel. This area in the cylinder may possibly be corroded, again keeping in mind that brake fluid is a hydroscopic liquid, which is very absorbent of moisture and moisture corrodes and could result in the piston jamming and not returning, therefore, causing the release mechanism to activate the clutch in a semi disengaged position.
    • Driver resting foot on clutch.
    • Lack of free travel and proper adjustment.
    • Wrong differential speed selected to match with chosen gear (trucks with 2 speed differentials).
    • Driver education for 1, 2, 4, and 6.
    • Check clutch release mechanism, air system and hydraulics for 3.
    • Adjust clutch to manufacture's specifications for 5.

No drive, noisy clutch.

  • Parts of the disc friction material are broken from rivet to rivet along with part of the cushioned segment. This is due to down shifting of gear i.e. the speed of the vehicle at the rear wheels was travelling faster than the engine RPM, when gear was changed down.

  • Driver education.

Power not transmitting to drive train because of broken facings.

    • Overloading vehicle.
    • Clutch disc has been replaced but not clutch pressure plate cover assembly.
    • Lack of applied load (inefficient diaphragm spring pressure or coil spring pressure).
    • Do not overload vehicle.
    • Replace with complete clutch kit.

Noisy and cannot transfer power/splines completely disintegrated.

    • Clutch disc not tested on spline before installation.
    • Missing spigot/pilot bearing or bushing.
    • Always check clutch disc for smooth sliding on spline.
    • Check and replace spigot/pilot bearing or bushing. (Mini UK & Europe: Check primary gear for worn bushing; if worn replace).