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Re: [Spridgets] 1275 pressure plate question

To: spridgets@autox.team.net
Subject: Re: [Spridgets] 1275 pressure plate question
From: Dave Grandeffo <davegran@tds.net>
Date: Thu, 07 May 2009 07:25:34 -0500
David Riker wrote:
> You would be right on most cars.  But the throw out bearing on a stock 
> A-series car doesn't have a true "throw out bearing".  It has a self 
> sacrificing carbon disc. More like a throw out bushing.  It does not 
> spin. Each of the parts of the MG clutch system were carefully 
> minimized by bean counters to last no longer than 30,000 miles and to 
> be completely worn out at almost the exact same time.  I also said 
> constant contact, not constant pressure.  The system is self 
> adjusting.  If a spring is added to pull the carbon disc away from the 
> mating surface on the pressure plate diaphram, it ceases to be self 
> adjusting. A return spring would always pull the throw out bearing 
> away from the pressure plate the maximum amount, requiring an 
> adjustable push rod be substituted for the non adjustable one, and you 
> would have to gradually lengthen the rod as the carbon bushing and 
> friction surfaces wear out.
> David R.
>
Let me qualify this then. *Disclaimer! Disclaimer!* *Opinion Follows!*

In.. my.. opinion,* *bearing or bushing, rotating or sliding; if there 
is no clutch free pedal then wear on both the throwout "device", 
pressure plate fingers, and the clutch plate will be accelerated. Since 
the master cylinder and the clutch cylinder always retract to the same 
position, in order for there to be "constant contact" throughout the 
life of the clutch and TO, there would have to be heavy contact when 
first installed. Furthermore, a clutch disk shouldn't wear much after 
its initial bedding in unless it's being slipped and overheated a lot, 
something that can happen if the pressure plate fingers are being 
depressed since the clutch isn't being clamped fully. Bean counters or 
not, if you are not getting more than 30 thousand miles out of a clutch 
assembly then the installation and/or the driver is at fault. As long as 
the clutch releases when you want it to, there is no reason not to have 
free pedal. By the way, free pedal will also help prevent overtraveling 
the pressure plate and wrecking it that way.

*Opinion Off*

-- 
Dave Grandeffo
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