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Re: Clutch Blintzes (Was: weber tuning)

To: zahid@serval.sps.mot.com
Subject: Re: Clutch Blintzes (Was: weber tuning)
From: pwv@tc.fluke.COM (Pat Vilbrandt)
Date: Mon, 2 Dec 91 09:09:05 PST
> Hmmmm which is the pilot bearing? 

It's the bearing (or bushing, possibly) either in the end of the crankshaft 
or the center of the flywheel that the end of the transmission input shaft 
rides in when the clutch is pressed.  Inexpensive little thing that can 
cause havoc when it gives out, since it not only allows the engine to turn 
while the transmission doesn't; it also keeps everything in alignment when 
the clutch is disengaged.  Moral of the story:  ALWAYS replace the pilot
bearing when you do clutch work.

> I replaced the clutch disk, pressure plate and throw-out bearing. The 
> flywheel surface was smooth.

Smooth or not, it's still a good idea to have the flywheel resurfaced when
the clutch disk & pressure plate are replaced.  I don't understand the 
metallurgy (or whatever), but it seems the flywheel surface gets "burnished"
or something, especially when you drive a car hard.  When you just throw in 
a new disk, you can expect it to be worn away quite quickly by the flywheel
surface.

I've seen a couple of extreme cases of this with big-block V8's and manual
transmissions (back when these were still common - oops!  I'm dating myself
again!) - replace the clutch disk & pressure plate, drive it hard, and the 
clutch would be slipping again within a month!  Re-surface the flywheel
along with the second new disk and pressure plate and the clutch would go
for another 30,000 mi+
 
> >(How do you know for sure that the pressure plate is toasted?)
> >   Pat Vilbrandt 
> 
> Well, there is no noise when I press the clutch indicating that the
> thrust bearing is fine oops! I meant throw-out bearing. But when I slowly
> let off the clutch there is a high pitched grinding noise as the clutch
> engages and this noise dissappears when my foot is off the pedal completely.

Sounds like something on the clutch disk is interfering with the flywheel/
pressure plate (or vice versa!).  Or the clutch disk has totally failed.
Let us know what you find.

   Pat Vilbrandt       John Fluke Mfg. Co., Inc.        Everett, Washington USA
UUCP: pwv@tc.fluke.COM  or: { uunet, uw-beaver, sun, microsoft }!fluke!pwv
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