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Re: Roller throwout bearing (WARNING!!)

To: "Bob" <Bob@itgonline.com>, "spridgets" <spridgets@Autox.Team.Net>
Subject: Re: Roller throwout bearing (WARNING!!)
From: "Mike Gigante" <mikeg@vicnet.net.au>
Date: Fri, 12 Dec 1997 08:39:36 +1100
Reply-to: "Mike Gigante" <mikeg@vicnet.net.au>
Sender: owner-spridgets@Autox.Team.Net
By rotating the bearing in the fork, I mean attach the bearing to the
throwout
fork, attach circlips, then try and swivel it. The 4-5 o'clock position and
the
7-8 o'clock positions may touch the throwout fork. If so, grind away the
plastic casing until you get at least 30-40 degrees of movement. I have a
ground
down bearing in the shed. I'll check later to see exactly what angle I
needed
to support.

The geometry of the fork, and the thickness of the roller bearing combine to
cause the "natural resting position" of the fork/bearing not to be flat, but
rather
something like

    pressure plate bearing face
   /
 /
*
*
*+++++++
*+           +
*+           +
*+    +     +      <- bearing
*+     |      +
*+    |       +
*++|+++++
*   |
   |    <- throwout fork
  |


I hope you get the idea. You can hopefully see that the resting position
of the bearing is "rotated" in the throwout fork and will press on the face
of the pressure plate if it can't rotate freely.

Note that there is *plenty* of spare plastic on the casing of the roller
bearings!!!

Caveat: the bearings we get here are probably the same ones you
get, but in case they aren't and you grind through to the bearing itself
I bear no responsibility!!!!

Mike

----------------------------------------------------------------------------
--------------------------------------
Mike Gigante                                       mikeg@vicnet.net.au
Watsons Creek Vineyard                     http://www.vicnet.net.au/~mikeg
----------------------------------------------------------------------------
--------------------------------------
-----Original Message-----
From: Bob <Bob@itgonline.com>
To: Mike Gigante <mikeg@vicnet.net.au>; spridgets <spridgets@autox.team.net>
Date: Friday, December 12, 1997 12:06 AM
Subject: Re: Roller throwout bearing (WARNING!!)


>Mike,
>
>Thanks for the heads up on the bearing.  I am not quite sure what you mean
by
>rotate the bearing in the fork.  I hve installed the bearing on the fork
and it
>seems to rotate freely.  Does the bearing actually make contact with
>the surface of the fork?
>
>Bob Magnotti
>59 RHD Sprite
>Fairfax, VA
>
>_______________________ Reply Separator _______________________
>
>Subject: Roller throwout bearing (WARNING!!)
>Author:  Mike Gigante <mikeg@vicnet.net.au> at internet
>Date:    12/10/97 8:04 PM
>
> I have used these successfully for a couple of years now, but my first
> experience with it was disasterous. It caused me to totally lose my
> clutch while sitting on the dummy grid at the annual six hour relay race.
> (Long time members of the british cars list may remember my report)
> I had to replace the pressure plate, clutch plate and roller bearing as a
> result of the failure.
>
> It turns out that the plastic casing (which is significantly larger around
> the back)
> can interfere with the throwout fork. This means that the throwout bearing
> is
> never fully dissengaged and spins at engine rpm. Also because of the
> geometry, the pressure isn't uniform, but is only on the lower part of the
> bearing.
>
> This will overheat the bearing causing it to fail with melted plastic and
> free ball
> bearings. It will also ruin the engagement face of the pressure plate.
>
> Fortunately, the cure is quite simple. You merely have to grind away the
> lower rear
> plastic until the bearing rotates freely in the fork. here is a very crude
> ascii form
>
>  *****
> *      *
> *      *
> *      *
> *  +  *
> *      *
> *     *
> *    *
> *  *
> ***
>
> Does that make sense? Anyhow rotate the bearing in the throwout fork
> until you are sure you've ground enough off.
>
> Once you have done this, you'll have no problems with them at all.
>
> Mike
>
> --------------------------------------------------------------------------
--
> --------------------------------------
> Mike Gigante                                       mikeg@vicnet.net.au
> Watsons Creek Vineyard                     http://www.vicnet.net.au/~mikeg
> --------------------------------------------------------------------------
--
> --------------------------------------
> -----Original Message-----
> From: Bob <Bob@itgonline.com>
> To: spridgets@autox.team.net <spridgets@autox.team.net>
> Date: Thursday, December 11, 1997 8:37 AM
> Subject: No Subject
>
>
> >I had purchased the new roller throw out bearing from MiniMania for my
> standard
> >LBC 4 speed.
> >I will not be installing the four speed in my Bugeye because I have
decided
> to
> >install
> >the Rivergate 5 speed conversion.  I was wondering if any of the
> >list readers has experience with the roller bearing throw out.  Several
> days
> >ago
> >there was a discussion about RPM drop when the standard clutch bushing is
> >engaged.  I have always
> >experienced this drop also and was wondering if the roller eliminated the
> drop.
> >
> >Also I have not yet completed my restoration and was  wondering  if the
> roller
> >bearing in the Rivergate conversion eliminates the RPM drop.
> >
> >Bob Magnotti
> >59 RHD Sprite
> >Fairfax, VA
> >
> >(This is the 4th time I sent this message, is the list adress case
> sensitive?)
> >
> >
>
>
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> From: "Mike Gigante" <mikeg@vicnet.net.au>
> To: "Bob" <Bob@itgonline.com>, <spridgets@autox.team.net>
> Subject: Roller throwout bearing (WARNING!!)
> Date: Thu, 11 Dec 1997 10:54:42 +1100
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