by RS13 » Wed May 21, 2014 11:35 pm
How I see it, when you install a new clutch, the pressure plate "fingers" are more or less perpendicular to the longitudinal axis of the input shaft. There is a very small clearance as you say, however as a clutch plate friction surface wears, the "fingers" begin to move toward the thrust bearing, closing the clearance until they're constantly touching the bearing surface. As the thrust bearing is now constantly spinning with effectively no thrust load, with worn races/bearings its' going to chatter/rattle.. however when you push the clutch pedal in the force applied to the thrust bearing now loads it up, the chattering stops and the clutch disengages. A good way to diagnose this is to gradually rest your foot on the clutch, the noise should lessen and disappear as the load is taken up. Often a very worn one will squeak/grind when the clutch pedal is pushed as well.
Have a listen to this;
http://www.youtube.com/watch?v=YCkk-hgNI2EAlso, I'd doubt that a later-model 1500cc Toyota would have an input shaft bearing/gear failure at 120kms.. although, it is easy to check the condition of the gearbox oil and oil drain magnet as there are likely indications of this. But if it were my car, changing the clutch is the cheapest starting point when it comes to rotational transmission noises, especially if it had done 120kms!
Daily driver: Toyota RunX/Toyota Caldina
Ex: 2x AE101, 5x KP60, KP61, EP71, 3x KE70, KE72, AE70, AE82, 2x TE71, AE90, AE92, ST170, plus 11 Hondas, 12 Nissans, 6 Fords, 4 Mazdas, 3 Mitsis, an Isuzu and a Lada!