How are you bleeding the system? The preferred method is to pull a
vacuum on the top of the reservoir and drawing out any air.
When you pump the pedal is the effort different than when the clutch
It almost has to be on the top if your not using any fluid.
Perhaps pull the master and see what the bore looks like, it almost
sounds like the piston seals are bypassing fluid.
I don't know this application - on the cars I am familiar with with
hydraulic clutch, there is no "pump" in the master cylinder, so any air in
the system is critical - the only and I mean ONLY way to bleed these (on
this particular car) is via a pressure bleeder. Air in the system will
cause the kind of effect described.
Normal pedal bleeding, depress, open bleeder, close bleeder, release
pedal, repeat... over and over and over.
Not noticeably, I think it's applying pressure to the clutch, but that
the reservoir valve in the MC isn't sealing properly at the start of the
stroke, so it doesn't have the displacement to fully release the clutch.
The bores are fine and no fluid is leaking from the MC, so not bypassing
those seals. The design of the MC is pretty crappy IMNSHO, with a
coaxial seal at the front of the piston that is supposed to seal off the
hole to the reservoir at the start of the stroke and then the spring
behind it just compresses as the stroke continues. Worse yet is this is
just a round pseudo-o-ring seal on a flat surface, not a real hard seat
soft seat seal setup. I think I could fab a much better design as well
as increasing total displacement a bit to provide more headroom.
Unless its a 94 or later Ford Ranger clutch...(Mazda included)
Then you have to mount the master...and pull the circlip that holds in
the clutch piston..and very gently pull it out until fluid starts to
drain on your floorboards. Only way.
'In the first place, we should insist that if the immigrant who comes here in
becomes an American and assimilates himself to us, he shall be treated on an
equality with everyone else, for it is an outrage to discriminate against any
because of creed, or birthplace, or origin. But this is predicated upon the
person's becoming in every facet an American, and nothing but an American...
There can be no divided allegiance here. Any man who says he is an American,
but something else also, isn't an American at all. We have room for but one flag,
the American flag... We have room for but one language here, and that is the
English language.. and we have room for but one sole loyalty and that is a
loyalty to the American people.'
Theodore Ro osevelt 1907
Try vacuum bleeding it. MUCH easier and you only need a hand pump to do it.
TSB - 01-07-31-002B
Improved Bleeding Procedure for Hydraulic Clutch Release System
Covers 2007 and prior GM cars and light trucks.
The basics are that you use a hand pump and a cover adapter and pull a
15-20 inch vacuum on the reservoir. Fill reservoir. Repeat as needed
until the bubbles stop or the fluid level doesn't drop.
Could be that the piston has a small tear or defect that prevents a seal.
Tim, that's about as simple a hydraulic project as there is.
The pressures are laughable. The only real consideration is whether the
volume of the MC is sufficient to move your slave piston the required
There are dozens of of clutch master cylinders available in the
aftermarket hot-rod catalogs. I'd bet money you aren't the first one
to do this exact project.
Persoanlly, I'd call Craig Taylor at Taylor Engineering in Dallas.
Nice guy, very helpful, and I bet he can tell you exactly what you
need off the top of his head.
You need the same overall mechanical advantage - main thing is the
bore of the master cyl - assuming the leverage on the pedal is the
Measure the bore of the clutch slave and the master of the original
install - calculate ratio. Then calculate the mechanical advantage of
the clutch pedal as a lever. Multiply them for the total MA.
If your replacement setup is close, you are OK. Low MA makes a heavy
On Tue, 21 Jul 2009 12:03:46 -0500, Tim Wescott wrote:
Comments here, plus perusal of some ads in Street Rodder (_why_ didn't I
think of that before?) lead me to think that I can make a suitable
linkage to place the clutch MS in decent place, then I'll use whatever
seems to have the right bore (hopefully cheap, from a junkyard).
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