The original hydraulic clutch system on the Spridgets is self adjusting. The
slave cylinder piston retracted just enough to keep the release bearing in
the immediate proximity of the pressure plate. This worked because of a lack
of a return spring on the release bearing arm. The pressure plate pushed the
slave cylinder piston back.
Since the Datsun release bearing arm assembly incorporates a return spring,
the slave cylinder piston is always fully retracted at rest. Depressing the
master cylinder moves the slave cylinder from a fully retracted position.
That means that the piston in the slave cylinder must move some amount
before the release bearing contacts the pressure plate. This lost motion is
likely why the clutch will not release.
IMHO, the answer is to use an adjustable rod on the slave cylinder and
adjust it to where you have about 1/8 to 1/4 inch of free play between the
release bearing and the pressure plate with the system at rest. I don't
believe this is an issue with cylinder diameter. Rather, it is a clutch
adjustment problem.
If you don't have and adjustable slave cylinder rod, I believe that Gerard
has them available.
Jim
-----Original Message-----
From: spridgets-bounces at autox.team.net
[mailto:spridgets-bounces at autox.team.net] On Behalf Of Hal Faulkner
Sent: Wednesday, August 03, 2011 4:10 PM
To: miniac7 at aol.com
Cc: spridgets at autox.team.net
Subject: Re: [Spridgets] Master cylinder
The confusion here stems from the fact that we are not being precise: we
have two cylinders and therefore need to be careful which end we are
talking about.
At the MASTER, a larger master moves more fluid with the same travel, but
needs more force to produce the same hydraulic pressure.
At the SLAVE, a larger cylinder (slave) needs more fluid to travel the same
distance, but will do so with less hydraulic pressure.
Since Joe is experiencing insufficient travel at the slave, he needs a
longer push rod to take up the excess slack. If this doesn't prove
sufficient he could use a smaller SLAVE to get more travel. OR he could use
a larger MASTER to move more fluid and get the same effect.
Joe apparently replaced his slave cylinder with one from Rivergate, if the
new SLAVE is larger it will move less. If the MASTER is smaller (*e.g*.,
3/4 instead of 7/8) it will mot move the slave cylinder as far.
He could possibly solve the situation with a longer pushrod at the slave.
Hal
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