Pressure Plate Finger Grooves, caused by the throwout bearing Options

[McMark]

Hey guys, check my logic here. I see this type of grooving all the time, on nearly every pressure plate I see - regardless of engine type, horsepower, etc. I hadn't given it too much thought other than, "I don't like it, but it happens every time." But I was just talking with someone and it occurred to me that this might be wear caused by a bad throwout bearing. If the grease is sticky, or if dirt has infiltrated the bearing, it may not be able to rotate/spin correctly and would slip causing wear.

The point of the throwout bearing should be to stop exactly this type of wear, right?
Doest this mean bad throwout bearings are super common?
Or is this a symptom of a loose clutch cable, not holding the throwout bearing tight to the fingers and that lets them slip?

[aircooledboy]

The point of the throwout bearing should be to stop exactly this type of wear, right?
Doest this mean bad throwout bearings are super common?
Or is this a symptom of a loose clutch cable, not holding the throwout bearing tight to the fingers and that lets them slip?

I always understood this was the opposite of a loose cable. I thought ideally your throw out should hover just out of contact with the pressure plate fingers to avoid premature wear to both the bearing and the pressure plate springs, but since many cars have their clutch cable too tight, you get this. (IMG:style_emoticons/default/confused24.gif)

[Dave_Darling]

I thought ideally your throw out should hover just out of contact with the pressure plate fingers ...

Not on a 914, at the very least! Remember, the 914 has a spring on the pedal cluster that pulls the pedal down in the "press the pedal" direction. That means there is always pressure on the throwout bearing--though not a lot.

This kind of wear is exceedingly common--maybe universal? I don't know why, because it seems to me that the T/O bearing should be there to prevent that. Especially if the bearing is always in contact with the fingers on the plate, so it should not have a chance to slip.

Maybe it would be worse without a real bearing in place?

Do you have photos of the throwout bearing?
What does the bearing surface look like?

The top of the bearing has a rounded surface. Basically it's just the inverse of the wear that you see in the pressure plate fingers in the pics above.

Here's a pic:
(IMG:http://www.914world.com/bbs2/uploads_offsite/www.pelicanparts.com-121-1418175958.1.jpg)


--DD