<VV> Topic: Odd noise and pressure plate

[Brian]

hen the car is in gear, the fingers on the pressure plate aren't touching anything.  Yet as I drive the car, there is a very pronounced knocking noise.  The balancer has not slipped.  All bearings were measured and correct bearings installed.  Ring gap measured correctly.  Entire assembly---crank, pressure plate and flywheel --balanced.  Engine torn down twice but nothing found.  Engine vibrates badly.  Pulls like crazy.  No smoke.  I'm bewildered and frustrated.

---------- Original Message ----------
From: MarK Durham via VirtualVairs <virtualvairs at corvair.org>
To: Ken Schifftner <scrubbr at ix.netcom.com>
Cc: virtualvairs at corvair.org
Subject: Re: <VV> Topic: Odd noise and pressure plate
Date: Wed, 21 May 2014 12:46:29 -0700

Ken, when you torque down a pressure plate all of the fingers should be the
same height so the throwout bearing can ride on all of them at the same
time. Also, the fingers should form a concentric hole that the t/o bearing
shaft fits into. I suggest the plate be inspected. Also, I would take a
good look at the harmonic balancer to make sure it has not started to come
apart. A out of balance pressure plate will cause the balancer to fail
because it is not designed to take those stresses.

Mark Durham Hauser Idaho
62 2Door Coupe 4speed Red/Red
On May 21, 2014 9:20 AM, "Ken Schifftner via VirtualVairs" <
virtualvairs at corvair.org> wrote:

> Gang:
>
> I recently was part of a crew that ran a rebuilt 140hp on an engine stand
> wherein the flywheel and pressure plate was exposed (just engine, bell
> housing, no transaxle). The engine had, when installed in the car, an odd
> rattle...random, not rhythmic. On the stand, there was perhaps some of the
> noise but not like the noise was when installed.
>
> While looking at the running engine from the point of view that the
> throwout bearing would have (if said bearing were installed), the pressure
> plate fingers were not cycling as if they had a common center. In other
> words, if you tried to put a pipe (or the like) on the same centerline as
> the crankshaft bushing, some of the fingers would hit. It was almost like
> some of the fingers were loose and centrifugal force was spreading them,
> while others didn't want to move. If the throwout bearing were to be
> installed, the fingers would not touch smoothly on the bearing but instead
> be eccentric and make like a polishing motion rather like a rotating motion
> (I hope I described this OK).
>
> Having never seen a running engine from this vantage point, I don't know
> if what I saw is "normal", "abnormal", or "panic inducing".  I'm thinking
> that the pressure plate may be shot...or at least has weak springs.  The
> flywheel seemed to be running smoothly however. Loose rivets?
>
> Other oddity. When using a timing light that provides a strobe like effect
> and shooting it towards the harmonic balancer, the image was
> fluttering....usually the image is fairly steady. Maybe the two things are
> related, I don't know.
>
>
> Ken Schifftner
>
> Kenneth Schifftner, Consultant, LLC
> 210 Indian Hollow Court
> Mahwah, NJ 07430
>
> 201-236-0786 hm/bz
> 201-749-3063 cell
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