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Re: MY Answer--Clutch Slave Cylinder "Throw"

To: "David R. Conrad" <conrad1@gte.net>, <datsun-roadsters@autox.team.net>
Subject: Re: MY Answer--Clutch Slave Cylinder "Throw"
From: bill <wschaibe@ucsd.edu>
Date: Mon, 29 Sep 2003 20:06:27 -0700
This is interesting as I just did the opposite swap.  The gizmo that threads
onto the adjustable push rod disintegrated on me so that my clutch pedal did
nothing.  My solution was to take the single piece push rod off an old stock
master cylinder and install it on my after market replacement.  I also had
another adjustable push rod but decided not to chance another one going bad
on me.  There is a slightly different feel to the clutch now but at least I
have a solid connection.

Bill
San Diego
70 16t00


>> 
> 
> I was hopeful, but I wasn't exactly "overwhelmed" by the number of answers to
> my question ;-).  I'll share my findings.
> 
> From the geometry of the linkage, and my own measurements of one SPL-311, I
> calculated that the maximum (theoretical, no "slop") slave cylinder "throw"
> should be 0.92 inches.  Because of the 5/8" to 3/4" piston diameters of the
> master and slave respectively. the slave moves 69.5% of the master movement.
> Mine traveled about 9/16ths inch which was not sufficient to provide release
> bearing clearance, and at the same time, sufficient "release" to allow non
> interference, that is, "grindingless" shifting.
> 
> In my spare parts, I had a "mystery" clutch master cylinder (also made by
> Tokico) which was, in many respects, very similar to that which is stock in
> the
> SPL-311.  It had a unique feature, an adjustable "push rod".  (It is shown in
> the "attachment", which will be "stripped" for List addressees.  I will be
> happy to supply to individuals if requested.)
> 
> I modified this adjustable push rod so that it could be substituted to the
> stock cylinder push rod, then installed the MC in the car.
> 
> I adjusted this push rod so that it would start immediately moving hydraulic
> fluid at the normal start  position of the clutch pedal.
> 
> Measurement of slave cylinder movement at full depression of the clutch pedal
> was a throw of 3/4 inch.  I figure that's about the "upper limit" of what the
> slave cylinder "throw" should be.
> 
> I returned slave cylinder clearance (to the release bearing) to be
> approximately 1/8th inch, where I had set it when I did my last clutch
> replacement.  This clearance had apparently "gone away" over time, unnoticed
> by
> me.
> 
> My clutch/shifting performance is greatly improved over what it has been for a
> long time.  (One of those things that gradually occurs and you don't realize
> the amount of degradation, until you "fix it".)
> 
> Dave
> '68 1600
> Kailua-Kona





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