Touching clutch and pp surfaces

[Russell Reay]

Originally Posted by BRENT in 10-uh-C

So what causes 'clutch chatter'? As mentioned, it can be an alignment issue however generally speaking, the gyro effect of a rotating mass always seeks a centerline which masks the alignment issue. So in other words, the chatter is usually light & subsides quickly.

The biggest cause of chatter in a Model-A driveline from my experiences is due to a worn Clutch Pilot Bearing, or a worn end of the Main Drive Gear (-a/k/a Input Shaft) where it enters the Pilot Bearing, or a worn Main Shaft Bearing. Any one of these (-or combination of the 3) allows the Clutch Disc to be outside of the Pressure Plate centerline. When the Clutch is engaged, it is trying to seek a centerline, and therefore causes chatter until it becomes centered with the P/P. It was mentioned that the chattering does not happen once at operating speeds and during shifting, ...which this is because the Main Drive Gear (-Input Shaft) is already rotating within the centerline and the gyroing effect basically maintains that centerline of the input shaft and clutch disc even when the pressure of the Pressure Plate has been momentarily released.

I am also skeptical of the significance of body oils, but I don't have the experience or credentials to argue the point. The pilot bearing is new as is the throwout bearing. When installing the flywheel and AA flywheel housing I recall checking everything with a dial indicator, but I foolishly did not record the results. I do remember that there was a little variation, but decided at the time they were not significant. After teardown and re-examination I may find my chatter source.