[Mgs] clutch slave cylinder question

[Paul Hunt]

Firstly new slave cylinders come with the bleed nipple in the wrong place.
The hose should be screwed into the port that faces forwards and the bleed
nipple in the one that faces across the car and is at the top.  This and the
drillings in the slave casting mean that any air in the *cylinder* will be
expelled from the bleed nipple as expected.  However the long vertical run of
large bore pipe from the master to the slave, together with the loop in the
pipe that is above the master, means that it isn't easy to bleed the *pipe*
from the top down even with a continuous flow system like the EeziBleed, and
more difficult again if you try to do it with the pedal.  If you have any air
left in the system at all it will compress of course so you won't get as much
movement of the slave piston as you should for the full travel of the pedal.
You should be getting about 1/2".  The design of the hydraulic system is such
that the first pump or two of the pedal will take up all mechanical play at
the clutch end, after that *any* movement of the slave push-rod should move
the clutch release arm, albeit not enough if there is air in the system.  Some
say wear in the slave clevis pin causes insufficient clutch travel, it
doesn't, that happens when the one at the *pedal* is worn and the push-rod and
pedal it connects, as I say the design of the hydraulic system takes account
of any and all mechanical wear at the slave end.

Reverse bleeding is best, this can either be done with the EeziBleed
jury-rigged to the slave nipple and using very low air pressure, but is
actually easier if you connect the slave and right caliper nipples with a
length of tubing (they are the same size), open both, then you can use the
brake pedal gently and slowly to reverse bleed the clutch.  This transfers
fluid from the brake master to the clutch, so you may need to drain some out
of the clutch to start with to make room, and make sure you don't bleed so
much that it lowers the level in the brake master too much.  Literally 3 or 4
strokes should be all that is required, then you can top off both masters as
required.

There is another method often mentioned which involves pushing the slave
piston all the way into the cylinder using the end of the clutch arm, which
can indeed move enough fluid from the cylinder to displace any air gathered in
the loop of pipe up by the master into the master and out of harms way.  But
you need to be careful releasing the clutch arm, there is a spring inside the
cylinder that will push the piston out again, and this can draw air past the
hydraulic seal in the slave cylinder so you are back where you started.  If
you do push the piston in with the clutch arm, then hold it there while
someone operates the *pedal* to push it back out again.

PaulH.
  ----- Original Message -----
  from underneath i see the rubber on the end of the slave unit expanding
when
  she pumps, but i don't see the arm move.  is that normal?