I'll ask my _second_ question _first_, so you can think about it while
you read my first question: What's a good newsgroup to post this sort of
question? I hate fora, so if there's an active newsgroup that'd be
vastly preferred.

My _first_ question is: are all clutch master cylinders created equal?

I'm putting a 2.8L V-6 into a Vega (to be followed by a 3.4L V-6 from GM
Performance Parts, if they survive the bankruptcy). I'm doing this
instead of a small block V-8 because I'm crazy, because the 2.8 block
lets be get at the spark plugs without jacking the motor up, and because
it'll help retain a halfway decent balance fore and aft (I hope).

Because I'm crazy I'm retaining the stick shift of the original, so I
need a clutch linkage. The transmission that fits well is from an '87
Camero (with 2.8L V-6), but it wants a hydraulic clutch instead of the
cable clutch which came on the Vega and the S-10 that donated the engine.

For a variety of reasons (mostly having to do with the advisability of
welding on unknown alloy cast aluminum) I don't want to modify the Camero
bellhousing. The S-10 bellhousing won't fit.

So I'm planning on finding the correct Camero clutch slave cylinder parts
that'll just bolt onto the bellhousing, but that leaves me with needing
to get the master cylinder mounted onto the firewall. I already know
it'll be a bitch; I'm planning on getting all of the Camero parts I can
(both pushrods, both cylinders, even bolts and tubing if I can). But if
the Camero master cylinder just won't fit, how much leeway do I have in
finding something that will? Do I get just any old thing? Is there an
interchange book that's accessible? Are different master cylinders with
different bores readily available, and how much can I compensate for
differing pedal-to-pushrod mechanical advantages by changing the master
cylinder bore? Are there any other differences I need to know (surely
there are some valving issues -- anything else?).

TIA.

--
www.wescottdesign.com

The Camaro unit is supposedly the "hot setup" for street rods because it
is so compact, but Wilwood also offers master & slave cylinders:
http://www.wilwood.com/Products/006-...SBMC/index.asp


"Tim Wescott" wrote in message
...
I'll ask my _second_ question _first_, so you can think about it while
you read my first question: What's a good newsgroup to post this sort of
question? I hate fora, so if there's an active newsgroup that'd be
vastly preferred.

My _first_ question is: are all clutch master cylinders created equal?

I'm putting a 2.8L V-6 into a Vega (to be followed by a 3.4L V-6 from GM
Performance Parts, if they survive the bankruptcy). I'm doing this
instead of a small block V-8 because I'm crazy, because the 2.8 block
lets be get at the spark plugs without jacking the motor up, and because
it'll help retain a halfway decent balance fore and aft (I hope).

Because I'm crazy I'm retaining the stick shift of the original, so I
need a clutch linkage. The transmission that fits well is from an '87
Camero (with 2.8L V-6), but it wants a hydraulic clutch instead of the
cable clutch which came on the Vega and the S-10 that donated the engine.

For a variety of reasons (mostly having to do with the advisability of
welding on unknown alloy cast aluminum) I don't want to modify the Camero
bellhousing. The S-10 bellhousing won't fit.

So I'm planning on finding the correct Camero clutch slave cylinder parts
that'll just bolt onto the bellhousing, but that leaves me with needing
to get the master cylinder mounted onto the firewall. I already know
it'll be a bitch; I'm planning on getting all of the Camero parts I can
(both pushrods, both cylinders, even bolts and tubing if I can). But if
the Camero master cylinder just won't fit, how much leeway do I have in
finding something that will? Do I get just any old thing? Is there an
interchange book that's accessible? Are different master cylinders with
different bores readily available, and how much can I compensate for
differing pedal-to-pushrod mechanical advantages by changing the master
cylinder bore? Are there any other differences I need to know (surely
there are some valving issues -- anything else?).

TIA.

--
www.wescottdesign.com

Tim Wescott wrote:
I'll ask my _second_ question _first_, so you can think about it while
you read my first question: What's a good newsgroup to post this sort of
question? I hate fora, so if there's an active newsgroup that'd be
vastly preferred.

My _first_ question is: are all clutch master cylinders created equal?

I'm putting a 2.8L V-6 into a Vega (to be followed by a 3.4L V-6 from GM
Performance Parts, if they survive the bankruptcy). I'm doing this
instead of a small block V-8 because I'm crazy, because the 2.8 block
lets be get at the spark plugs without jacking the motor up, and because
it'll help retain a halfway decent balance fore and aft (I hope).

Because I'm crazy I'm retaining the stick shift of the original, so I
need a clutch linkage. The transmission that fits well is from an '87
Camero (with 2.8L V-6), but it wants a hydraulic clutch instead of the
cable clutch which came on the Vega and the S-10 that donated the engine.

For a variety of reasons (mostly having to do with the advisability of
welding on unknown alloy cast aluminum) I don't want to modify the Camero
bellhousing. The S-10 bellhousing won't fit.

So I'm planning on finding the correct Camero clutch slave cylinder parts
that'll just bolt onto the bellhousing, but that leaves me with needing
to get the master cylinder mounted onto the firewall. I already know
it'll be a bitch; I'm planning on getting all of the Camero parts I can
(both pushrods, both cylinders, even bolts and tubing if I can). But if
the Camero master cylinder just won't fit, how much leeway do I have in
finding something that will? Do I get just any old thing? Is there an
interchange book that's accessible? Are different master cylinders with
different bores readily available, and how much can I compensate for
differing pedal-to-pushrod mechanical advantages by changing the master
cylinder bore? Are there any other differences I need to know (surely
there are some valving issues -- anything else?).

TIA.


The Camaro set-up should fit without much work. I used the set-up from
an S-Series on the 4.3 in a Vega I had a few years ago. Plenty of room.

--
Steve W.

On Tue, 21 Jul 2009 12:03:46 -0500, Tim Wescott
wrote:

snip
So I'm planning on finding the correct Camero clutch slave cylinder parts
that'll just bolt onto the bellhousing, but that leaves me with needing
to get the master cylinder mounted onto the firewall. I already know
it'll be a bitch; I'm planning on getting all of the Camero parts I can
(both pushrods, both cylinders, even bolts and tubing if I can). But if
the Camero master cylinder just won't fit, how much leeway do I have in
finding something that will?

Hydraulic clutches have been around for some time. It was
the slick way to go years ago when friends were building
their own dune buggy's. Back then they had pedal kits
(clutch, brake and throttle too as I recall) and slaves to
go with. A quick Google search brings up a bunch of stuff.
Maybe some place like this:

http://www.classicchevy5speed.com/Hy...lutch-Kit.aspx

Your the best one to decide if you want to get a ready made
aftermarket kit or piece something together and hope for the
best (shrug).

--
Leon Fisk
Grand Rapids MI/Zone 5b
Remove no.spam for email

I can't help on you question, but if there are any GM clutch master
cylinder experts out there I'd like to hear from them. I've been
fighting with the POS GM clutch MCs on my truck for quite some time and
am about ready to fabricate my own MC and be done with their garbage.
I'm not sure the slave cylinder is much better either, but it's more
work to try to fabricate one. The problems I keep having are with
intermittent failure to release, very irritating.

"Tim Wescott" wrote in message
...

You might also try alt.trucks.chevy, since a truck part is involved.

On Tue, 21 Jul 2009 14:16:24 -0400, Steve W. wrote:

Tim Wescott wrote:
I'll ask my _second_ question _first_, so you can think about it while
you read my first question: What's a good newsgroup to post this sort
of question? I hate fora, so if there's an active newsgroup that'd be
vastly preferred.

My _first_ question is: are all clutch master cylinders created equal?

I'm putting a 2.8L V-6 into a Vega (to be followed by a 3.4L V-6 from
GM Performance Parts, if they survive the bankruptcy). I'm doing this
instead of a small block V-8 because I'm crazy, because the 2.8 block
lets be get at the spark plugs without jacking the motor up, and
because it'll help retain a halfway decent balance fore and aft (I
hope).

Because I'm crazy I'm retaining the stick shift of the original, so I
need a clutch linkage. The transmission that fits well is from an '87
Camero (with 2.8L V-6), but it wants a hydraulic clutch instead of the
cable clutch which came on the Vega and the S-10 that donated the
engine.

For a variety of reasons (mostly having to do with the advisability of
welding on unknown alloy cast aluminum) I don't want to modify the
Camero bellhousing. The S-10 bellhousing won't fit.

So I'm planning on finding the correct Camero clutch slave cylinder
parts that'll just bolt onto the bellhousing, but that leaves me with
needing to get the master cylinder mounted onto the firewall. I
already know it'll be a bitch; I'm planning on getting all of the
Camero parts I can (both pushrods, both cylinders, even bolts and
tubing if I can). But if the Camero master cylinder just won't fit,
how much leeway do I have in finding something that will? Do I get
just any old thing? Is there an interchange book that's accessible?
Are different master cylinders with different bores readily available,
and how much can I compensate for differing pedal-to-pushrod mechanical
advantages by changing the master cylinder bore? Are there any other
differences I need to know (surely there are some valving issues --
anything else?).

TIA.


The Camaro set-up should fit without much work. I used the set-up from
an S-Series on the 4.3 in a Vega I had a few years ago. Plenty of room.

Do you have a picture or ten? One thing I didn't mention is that it
looks like the push rod from the pedal needs to go right through the fuse
panel.

Or did you just move/replace the fuses as a matter of course?

--
www.wescottdesign.com

Tim Wescott wrote:
My _first_ question is: are all clutch master cylinders created equal?

So I'm planning on finding the correct Camero clutch slave cylinder parts
that'll just bolt onto the bellhousing, but that leaves me with needing
to get the master cylinder mounted onto the firewall. I already know
it'll be a bitch; I'm planning on getting all of the Camero parts I can
(both pushrods, both cylinders, even bolts and tubing if I can). But if
the Camero master cylinder just won't fit, how much leeway do I have in
finding something that will? Do I get just any old thing? Is there an
interchange book that's accessible? Are different master cylinders with
different bores readily available, and how much can I compensate for
differing pedal-to-pushrod mechanical advantages by changing the master
cylinder bore? Are there any other differences I need to know (surely
there are some valving issues -- anything else?).

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
distance.
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.

On Tue, 21 Jul 2009 13:26:27 -0500, "Pete C."
wrote:


I can't help on you question, but if there are any GM clutch master
cylinder experts out there I'd like to hear from them. I've been
fighting with the POS GM clutch MCs on my truck for quite some time and
am about ready to fabricate my own MC and be done with their garbage.
I'm not sure the slave cylinder is much better either, but it's more
work to try to fabricate one. The problems I keep having are with
intermittent failure to release, very irritating.

Any chance that you have had the flywheel ground?

Way back, when GM first went to the hydraulic clutch in
there pickup trucks this caused headaches. My brother-inlaw
had his flywheel ground when he replaced the clutch. Then he
had problems getting it to release. Back then they had two
special spacer plates to solve the problem. That was what he
ended up having to do, tear it back down and install a
spacer plate (between the flywheel and motor side).

Personally, I would much rather have a mechanical clutch

--
Leon Fisk
Grand Rapids MI/Zone 5b
Remove no.spam for email

Leon Fisk wrote:
On Tue, 21 Jul 2009 13:26:27 -0500, "Pete C."
wrote:

I can't help on you question, but if there are any GM clutch master
cylinder experts out there I'd like to hear from them. I've been
fighting with the POS GM clutch MCs on my truck for quite some time and
am about ready to fabricate my own MC and be done with their garbage.
I'm not sure the slave cylinder is much better either, but it's more
work to try to fabricate one. The problems I keep having are with
intermittent failure to release, very irritating.

Any chance that you have had the flywheel ground?

Way back, when GM first went to the hydraulic clutch in
there pickup trucks this caused headaches. My brother-inlaw
had his flywheel ground when he replaced the clutch. Then he
had problems getting it to release. Back then they had two
special spacer plates to solve the problem. That was what he
ended up having to do, tear it back down and install a
spacer plate (between the flywheel and motor side).

Personally, I would much rather have a mechanical clutch

Not me! I've dealt with bent forks, bent bellcranks, stretched and
broken cables for decades.
Make mine hydraulic. For that matter, the concentric slave cylinders
are pretty slick if they weren't so hard to change out.

Was it Saab that mounted it on the front of the engine where it was easy
to get to?

Leon Fisk wrote:

On Tue, 21 Jul 2009 13:26:27 -0500, "Pete C."
wrote:


I can't help on you question, but if there are any GM clutch master
cylinder experts out there I'd like to hear from them. I've been
fighting with the POS GM clutch MCs on my truck for quite some time and
am about ready to fabricate my own MC and be done with their garbage.
I'm not sure the slave cylinder is much better either, but it's more
work to try to fabricate one. The problems I keep having are with
intermittent failure to release, very irritating.

Any chance that you have had the flywheel ground?

Way back, when GM first went to the hydraulic clutch in
there pickup trucks this caused headaches. My brother-inlaw
had his flywheel ground when he replaced the clutch. Then he
had problems getting it to release. Back then they had two
special spacer plates to solve the problem. That was what he
ended up having to do, tear it back down and install a
spacer plate (between the flywheel and motor side).

Personally, I would much rather have a mechanical clutch

No grinding or anything, just continual clutch no-release problems.
Clutch replaced once, coaxial slave cylinder replaced another time, MCs
replaced like four times. Never had a problem with clutch slip, only
failure to release.

Now that I have a new truck, I'm getting ready to pull the clutch on the
old one myself and see if I can fix it for good. This truck also ate
rear axle seals until I got into it. Axles seals replaced under warranty
several times, when they went again out of warranty I replaced them
myself and haven't had a problem since (195k+ now).

Tim Wescott wrote:
On Tue, 21 Jul 2009 14:16:24 -0400, Steve W. wrote:

Tim Wescott wrote:
I'll ask my _second_ question _first_, so you can think about it while
you read my first question: What's a good newsgroup to post this sort
of question? I hate fora, so if there's an active newsgroup that'd be
vastly preferred.

My _first_ question is: are all clutch master cylinders created equal?

I'm putting a 2.8L V-6 into a Vega (to be followed by a 3.4L V-6 from
GM Performance Parts, if they survive the bankruptcy). I'm doing this
instead of a small block V-8 because I'm crazy, because the 2.8 block
lets be get at the spark plugs without jacking the motor up, and
because it'll help retain a halfway decent balance fore and aft (I
hope).

Because I'm crazy I'm retaining the stick shift of the original, so I
need a clutch linkage. The transmission that fits well is from an '87
Camero (with 2.8L V-6), but it wants a hydraulic clutch instead of the
cable clutch which came on the Vega and the S-10 that donated the
engine.

For a variety of reasons (mostly having to do with the advisability of
welding on unknown alloy cast aluminum) I don't want to modify the
Camero bellhousing. The S-10 bellhousing won't fit.

So I'm planning on finding the correct Camero clutch slave cylinder
parts that'll just bolt onto the bellhousing, but that leaves me with
needing to get the master cylinder mounted onto the firewall. I
already know it'll be a bitch; I'm planning on getting all of the
Camero parts I can (both pushrods, both cylinders, even bolts and
tubing if I can). But if the Camero master cylinder just won't fit,
how much leeway do I have in finding something that will? Do I get
just any old thing? Is there an interchange book that's accessible?
Are different master cylinders with different bores readily available,
and how much can I compensate for differing pedal-to-pushrod mechanical
advantages by changing the master cylinder bore? Are there any other
differences I need to know (surely there are some valving issues --
anything else?).

TIA.


The Camaro set-up should fit without much work. I used the set-up from
an S-Series on the 4.3 in a Vega I had a few years ago. Plenty of room.

Do you have a picture or ten? One thing I didn't mention is that it
looks like the push rod from the pedal needs to go right through the fuse
panel.

Or did you just move/replace the fuses as a matter of course?


Wasn't hard. Just made a simple plate out of 1/8". Welded it in place
and used that plate to mount the clutch master. I did alter the push rod
length so that the mounting flange was inside the firewall and remote
mounted the reservoir. I have also seen one mounted out in the air duct,
that one had a long bell crank shaft to reach it.

Moved the fuse box on mine because I built my own wiring harness anyway.
Used a painless box and universal kit.

The last built rig I had went down the road a few weeks ago. That was an
Olds Starfire GT (Monza clone) that I stuck a well tuned 3.8 turbo in.
That car had a 5 speed behind it and could really stick to the road.

Current project beast is a 70 Nova. It will end up with a perimeter
frame, 'vette rear suspension, tubular A arm front suspension (current
plan is coil overs but may use torsion bars instead)
Current power plant idea is an injected big block. Might make it a green
mobile and burn alcohol!

--
Steve W.

Pete C. wrote:
No grinding or anything, just continual clutch no-release problems.
Clutch replaced once, coaxial slave cylinder replaced another time, MCs
replaced like four times. Never had a problem with clutch slip, only
failure to release.

Now that I have a new truck, I'm getting ready to pull the clutch on the
old one myself and see if I can fix it for good. This truck also ate
rear axle seals until I got into it. Axles seals replaced under warranty
several times, when they went again out of warranty I replaced them
myself and haven't had a problem since (195k+ now).

Step down and no release? If you step down a second time does it release
then?


--
Steve W.

"Steve W." wrote:

Pete C. wrote:
No grinding or anything, just continual clutch no-release problems.
Clutch replaced once, coaxial slave cylinder replaced another time, MCs
replaced like four times. Never had a problem with clutch slip, only
failure to release.

Now that I have a new truck, I'm getting ready to pull the clutch on the
old one myself and see if I can fix it for good. This truck also ate
rear axle seals until I got into it. Axles seals replaced under warranty
several times, when they went again out of warranty I replaced them
myself and haven't had a problem since (195k+ now).

Step down and no release?

Yep, makes it kinds difficult to shift. Bit of a problem when you need
to stop as well.

If you step down a second time does it release
then?

Nope, pump it a half dozen times and you might get it to release enough
to shift with a clunk. Doesn't do it all the time either, can be working
just fine then start acting up.

I have no good way to monitor it for testing, but I suspect the MC
reservoir valve isn't sealing well allowing some of the stroke output to
simply go back to the reservoir.

I expect I could fabricate a better MC setup and add a bit more
displacement as well since I've always felt it bordered on not enough
displacement.

On Tue, 21 Jul 2009 12:03:46 -0500, Tim Wescott
wrote:

I'll ask my _second_ question _first_, so you can think about it while
you read my first question: What's a good newsgroup to post this sort of
question? I hate fora, so if there's an active newsgroup that'd be
vastly preferred.

My _first_ question is: are all clutch master cylinders created equal?

I'm putting a 2.8L V-6 into a Vega (to be followed by a 3.4L V-6 from GM
Performance Parts, if they survive the bankruptcy). I'm doing this
instead of a small block V-8 because I'm crazy, because the 2.8 block
lets be get at the spark plugs without jacking the motor up, and because
it'll help retain a halfway decent balance fore and aft (I hope).

Because I'm crazy I'm retaining the stick shift of the original, so I
need a clutch linkage. The transmission that fits well is from an '87
Camero (with 2.8L V-6), but it wants a hydraulic clutch instead of the
cable clutch which came on the Vega and the S-10 that donated the engine.

For a variety of reasons (mostly having to do with the advisability of
welding on unknown alloy cast aluminum) I don't want to modify the Camero
bellhousing. The S-10 bellhousing won't fit.

So I'm planning on finding the correct Camero clutch slave cylinder parts
that'll just bolt onto the bellhousing, but that leaves me with needing
to get the master cylinder mounted onto the firewall. I already know
it'll be a bitch; I'm planning on getting all of the Camero parts I can
(both pushrods, both cylinders, even bolts and tubing if I can). But if
the Camero master cylinder just won't fit, how much leeway do I have in
finding something that will? Do I get just any old thing? Is there an
interchange book that's accessible? Are different master cylinders with
different bores readily available, and how much can I compensate for
differing pedal-to-pushrod mechanical advantages by changing the master
cylinder bore? Are there any other differences I need to know (surely
there are some valving issues -- anything else?).

TIA.
You need the same overall mechanical advantage - main thing is the
bore of the master cyl - assuming the leverage on the pedal is the
same.

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
pedal.

On Tue, 21 Jul 2009 17:54:04 -0500, "Pete C."
wrote:


"Steve W." wrote:

Pete C. wrote:
No grinding or anything, just continual clutch no-release problems.
Clutch replaced once, coaxial slave cylinder replaced another time, MCs
replaced like four times. Never had a problem with clutch slip, only
failure to release.

Now that I have a new truck, I'm getting ready to pull the clutch on the
old one myself and see if I can fix it for good. This truck also ate
rear axle seals until I got into it. Axles seals replaced under warranty
several times, when they went again out of warranty I replaced them
myself and haven't had a problem since (195k+ now).

Step down and no release?

Yep, makes it kinds difficult to shift. Bit of a problem when you need
to stop as well.

If you step down a second time does it release
then?

Nope, pump it a half dozen times and you might get it to release enough
to shift with a clunk. Doesn't do it all the time either, can be working
just fine then start acting up.

I have no good way to monitor it for testing, but I suspect the MC
reservoir valve isn't sealing well allowing some of the stroke output to
simply go back to the reservoir.

I expect I could fabricate a better MC setup and add a bit more
displacement as well since I've always felt it bordered on not enough
displacement.
How close is the fluid line to a manifold? How old is the fluid? Sure
sounds like vapour fade due to inferior fluid or overheated lines.

wrote:

On Tue, 21 Jul 2009 17:54:04 -0500, "Pete C."
wrote:


"Steve W." wrote:

Pete C. wrote:
No grinding or anything, just continual clutch no-release problems.
Clutch replaced once, coaxial slave cylinder replaced another time, MCs
replaced like four times. Never had a problem with clutch slip, only
failure to release.

Now that I have a new truck, I'm getting ready to pull the clutch on the
old one myself and see if I can fix it for good. This truck also ate
rear axle seals until I got into it. Axles seals replaced under warranty
several times, when they went again out of warranty I replaced them
myself and haven't had a problem since (195k+ now).

Step down and no release?

Yep, makes it kinds difficult to shift. Bit of a problem when you need
to stop as well.

If you step down a second time does it release
then?

Nope, pump it a half dozen times and you might get it to release enough
to shift with a clunk. Doesn't do it all the time either, can be working
just fine then start acting up.

I have no good way to monitor it for testing, but I suspect the MC
reservoir valve isn't sealing well allowing some of the stroke output to
simply go back to the reservoir.

I expect I could fabricate a better MC setup and add a bit more
displacement as well since I've always felt it bordered on not enough
displacement.

How close is the fluid line to a manifold?

Not particularly close, probably 6" from the manifold, 3" from the pipe
heading down to where it crosses under the clutch bellhousing.

How old is the fluid?

A month or so since I last replaced the MC and flushed a good pint
through and out the coaxial slave cylinder breather.

Sure
sounds like vapour fade due to inferior fluid or overheated lines.

Sounds like it, and some of the cases of it acting up have been after
it's had some time to heat up, but other have been acting up from cold.

I suppose I could find some insulating wrap and wrap the line. Not sure
on inferior fluid, it just uses DOT3 brake fluid. The last couple pints
have just been generic DOT3, is there a particular brand I should look
for?

On Tue, 21 Jul 2009 22:11:38 -0500, "Pete C."
wrote:


wrote:

On Tue, 21 Jul 2009 17:54:04 -0500, "Pete C."
wrote:


"Steve W." wrote:

Pete C. wrote:
No grinding or anything, just continual clutch no-release problems.
Clutch replaced once, coaxial slave cylinder replaced another time, MCs
replaced like four times. Never had a problem with clutch slip, only
failure to release.

Now that I have a new truck, I'm getting ready to pull the clutch on the
old one myself and see if I can fix it for good. This truck also ate
rear axle seals until I got into it. Axles seals replaced under warranty
several times, when they went again out of warranty I replaced them
myself and haven't had a problem since (195k+ now).

Step down and no release?

Yep, makes it kinds difficult to shift. Bit of a problem when you need
to stop as well.

If you step down a second time does it release
then?

Nope, pump it a half dozen times and you might get it to release enough
to shift with a clunk. Doesn't do it all the time either, can be working
just fine then start acting up.

I have no good way to monitor it for testing, but I suspect the MC
reservoir valve isn't sealing well allowing some of the stroke output to
simply go back to the reservoir.

I expect I could fabricate a better MC setup and add a bit more
displacement as well since I've always felt it bordered on not enough
displacement.

How close is the fluid line to a manifold?

Not particularly close, probably 6" from the manifold, 3" from the pipe
heading down to where it crosses under the clutch bellhousing.

How old is the fluid?

A month or so since I last replaced the MC and flushed a good pint
through and out the coaxial slave cylinder breather.

Sure
sounds like vapour fade due to inferior fluid or overheated lines.

Sounds like it, and some of the cases of it acting up have been after
it's had some time to heat up, but other have been acting up from cold.

I suppose I could find some insulating wrap and wrap the line. Not sure
on inferior fluid, it just uses DOT3 brake fluid. The last couple pints
have just been generic DOT3, is there a particular brand I should look
for?
DON"T use heat wrap - use a properly positioned heat sheild and you
should be using DOT4 fluid, not DOT3.. The best heat sheild is a
stainless steel sheet midway between the heat source and the tube - or
half of a 2" stainless steel tube mounted so it semi-surrounds the
tubeing, about 1" from the tubing.. Three inches from the crossover
without a heat sheild is TOO CLOSE.
Might get by with DOT4 or DOT5 fluid, but you are still pushing it.

Pete C. wrote:
"Steve W." wrote:
Pete C. wrote:
No grinding or anything, just continual clutch no-release problems.
Clutch replaced once, coaxial slave cylinder replaced another time, MCs
replaced like four times. Never had a problem with clutch slip, only
failure to release.

Now that I have a new truck, I'm getting ready to pull the clutch on the
old one myself and see if I can fix it for good. This truck also ate
rear axle seals until I got into it. Axles seals replaced under warranty
several times, when they went again out of warranty I replaced them
myself and haven't had a problem since (195k+ now).
Step down and no release?

Yep, makes it kinds difficult to shift. Bit of a problem when you need
to stop as well.

If you step down a second time does it release
then?

Nope, pump it a half dozen times and you might get it to release enough
to shift with a clunk. Doesn't do it all the time either, can be working
just fine then start acting up.

I have no good way to monitor it for testing, but I suspect the MC
reservoir valve isn't sealing well allowing some of the stroke output to
simply go back to the reservoir.

I expect I could fabricate a better MC setup and add a bit more
displacement as well since I've always felt it bordered on not enough
displacement.

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
does work?

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.

--
Steve W.

"Steve W." wrote in message
...
Pete C. wrote:

snip

When you pump the pedal is the effort different than when the clutch
does work?

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.

--
Steve W.

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.

wrote:

On Tue, 21 Jul 2009 22:11:38 -0500, "Pete C."
wrote:


wrote:

On Tue, 21 Jul 2009 17:54:04 -0500, "Pete C."
wrote:


"Steve W." wrote:

Pete C. wrote:
No grinding or anything, just continual clutch no-release problems.
Clutch replaced once, coaxial slave cylinder replaced another time, MCs
replaced like four times. Never had a problem with clutch slip, only
failure to release.

Now that I have a new truck, I'm getting ready to pull the clutch on the
old one myself and see if I can fix it for good. This truck also ate
rear axle seals until I got into it. Axles seals replaced under warranty
several times, when they went again out of warranty I replaced them
myself and haven't had a problem since (195k+ now).

Step down and no release?

Yep, makes it kinds difficult to shift. Bit of a problem when you need
to stop as well.

If you step down a second time does it release
then?

Nope, pump it a half dozen times and you might get it to release enough
to shift with a clunk. Doesn't do it all the time either, can be working
just fine then start acting up.

I have no good way to monitor it for testing, but I suspect the MC
reservoir valve isn't sealing well allowing some of the stroke output to
simply go back to the reservoir.

I expect I could fabricate a better MC setup and add a bit more
displacement as well since I've always felt it bordered on not enough
displacement.

How close is the fluid line to a manifold?

Not particularly close, probably 6" from the manifold, 3" from the pipe
heading down to where it crosses under the clutch bellhousing.

How old is the fluid?

A month or so since I last replaced the MC and flushed a good pint
through and out the coaxial slave cylinder breather.

Sure
sounds like vapour fade due to inferior fluid or overheated lines.

Sounds like it, and some of the cases of it acting up have been after
it's had some time to heat up, but other have been acting up from cold.

I suppose I could find some insulating wrap and wrap the line. Not sure
on inferior fluid, it just uses DOT3 brake fluid. The last couple pints
have just been generic DOT3, is there a particular brand I should look
for?
DON"T use heat wrap - use a properly positioned heat sheild and you
should be using DOT4 fluid, not DOT3.. The best heat sheild is a
stainless steel sheet midway between the heat source and the tube - or
half of a 2" stainless steel tube mounted so it semi-surrounds the
tubeing, about 1" from the tubing.. Three inches from the crossover
without a heat sheild is TOO CLOSE.
Might get by with DOT4 or DOT5 fluid, but you are still pushing it.

I'll see what I can find to fab a shield. What about heat wrap on the
pipe where it crosses under?

If I change to a DOT4 or DOT5 fluid what kind of cleaning would I have
to do and would there be seal material compatibility issues? Brands of
fluid to look for?

"Steve W." wrote:

Pete C. wrote:
"Steve W." wrote:
Pete C. wrote:
No grinding or anything, just continual clutch no-release problems.
Clutch replaced once, coaxial slave cylinder replaced another time, MCs
replaced like four times. Never had a problem with clutch slip, only
failure to release.

Now that I have a new truck, I'm getting ready to pull the clutch on the
old one myself and see if I can fix it for good. This truck also ate
rear axle seals until I got into it. Axles seals replaced under warranty
several times, when they went again out of warranty I replaced them
myself and haven't had a problem since (195k+ now).
Step down and no release?

Yep, makes it kinds difficult to shift. Bit of a problem when you need
to stop as well.

If you step down a second time does it release
then?

Nope, pump it a half dozen times and you might get it to release enough
to shift with a clunk. Doesn't do it all the time either, can be working
just fine then start acting up.

I have no good way to monitor it for testing, but I suspect the MC
reservoir valve isn't sealing well allowing some of the stroke output to
simply go back to the reservoir.

I expect I could fabricate a better MC setup and add a bit more
displacement as well since I've always felt it bordered on not enough
displacement.

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.

Normal pedal bleeding, depress, open bleeder, close bleeder, release
pedal, repeat... over and over and over.


When you pump the pedal is the effort different than when the clutch
does work?

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.


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.

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.

Bill Noble wrote:

"Steve W." wrote in message
...
Pete C. wrote:

snip

When you pump the pedal is the effort different than when the clutch
does work?

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.

--
Steve W.

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.

Air in the system will cause a spongy pedal feel (which I don't get) and
will not be intermittent (which this problem is).

"Pete C." wrote:

wrote:

On Tue, 21 Jul 2009 22:11:38 -0500, "Pete C."
wrote:


wrote:

On Tue, 21 Jul 2009 17:54:04 -0500, "Pete C."
wrote:


"Steve W." wrote:

Pete C. wrote:
No grinding or anything, just continual clutch no-release problems.
Clutch replaced once, coaxial slave cylinder replaced another time, MCs
replaced like four times. Never had a problem with clutch slip, only
failure to release.

Now that I have a new truck, I'm getting ready to pull the clutch on the
old one myself and see if I can fix it for good. This truck also ate
rear axle seals until I got into it. Axles seals replaced under warranty
several times, when they went again out of warranty I replaced them
myself and haven't had a problem since (195k+ now).

Step down and no release?

Yep, makes it kinds difficult to shift. Bit of a problem when you need
to stop as well.

If you step down a second time does it release
then?

Nope, pump it a half dozen times and you might get it to release enough
to shift with a clunk. Doesn't do it all the time either, can be working
just fine then start acting up.

I have no good way to monitor it for testing, but I suspect the MC
reservoir valve isn't sealing well allowing some of the stroke output to
simply go back to the reservoir.

I expect I could fabricate a better MC setup and add a bit more
displacement as well since I've always felt it bordered on not enough
displacement.

How close is the fluid line to a manifold?

Not particularly close, probably 6" from the manifold, 3" from the pipe
heading down to where it crosses under the clutch bellhousing.

How old is the fluid?

A month or so since I last replaced the MC and flushed a good pint
through and out the coaxial slave cylinder breather.

Sure
sounds like vapour fade due to inferior fluid or overheated lines.

Sounds like it, and some of the cases of it acting up have been after
it's had some time to heat up, but other have been acting up from cold.

I suppose I could find some insulating wrap and wrap the line. Not sure
on inferior fluid, it just uses DOT3 brake fluid. The last couple pints
have just been generic DOT3, is there a particular brand I should look
for?
DON"T use heat wrap - use a properly positioned heat sheild and you
should be using DOT4 fluid, not DOT3.. The best heat sheild is a
stainless steel sheet midway between the heat source and the tube - or
half of a 2" stainless steel tube mounted so it semi-surrounds the
tubeing, about 1" from the tubing.. Three inches from the crossover
without a heat sheild is TOO CLOSE.
Might get by with DOT4 or DOT5 fluid, but you are still pushing it.

I'll see what I can find to fab a shield. What about heat wrap on the
pipe where it crosses under?

If I change to a DOT4 or DOT5 fluid what kind of cleaning would I have
to do and would there be seal material compatibility issues? Brands of
fluid to look for?

I see that there is a Valvoline brand DOT3/DOT4 fluid rated at 480 deg F
and seems to be compatible with regular DOT3, so I should be able to
upgrade by just flushing that stuff through. I'll also put some heat
wrap around the exhaust pipe in the problem area to try to keep the heat
in there, and fab a radiant shield (probably AL since I have material)
to put between the pipe and clutch line.

On Wed, 22 Jul 2009 08:23:19 -0500, "Pete C."
wrote:

displacement.

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.

Normal pedal bleeding, depress, open bleeder, close bleeder, release
pedal, repeat... over and over and over.

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.


Gunner

'In the first place, we should insist that if the immigrant who comes here in good faith
becomes an American and assimilates himself to us, he shall be treated on an exact
equality with everyone else, for it is an outrage to discriminate against any such man
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

Gunner Asch wrote:

On Wed, 22 Jul 2009 08:23:19 -0500, "Pete C."
wrote:

displacement.

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.

Normal pedal bleeding, depress, open bleeder, close bleeder, release
pedal, repeat... over and over and over.

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.

'97 Chev. clutch. It bleeds and will work properly, the problem is
intermittent.

Pete C. wrote:
"Steve W." wrote:
Pete C. wrote:
"Steve W." wrote:
Pete C. wrote:
No grinding or anything, just continual clutch no-release problems.
Clutch replaced once, coaxial slave cylinder replaced another time, MCs
replaced like four times. Never had a problem with clutch slip, only
failure to release.

Now that I have a new truck, I'm getting ready to pull the clutch on the
old one myself and see if I can fix it for good. This truck also ate
rear axle seals until I got into it. Axles seals replaced under warranty
several times, when they went again out of warranty I replaced them
myself and haven't had a problem since (195k+ now).
Step down and no release?
Yep, makes it kinds difficult to shift. Bit of a problem when you need
to stop as well.

If you step down a second time does it release
then?
Nope, pump it a half dozen times and you might get it to release enough
to shift with a clunk. Doesn't do it all the time either, can be working
just fine then start acting up.

I have no good way to monitor it for testing, but I suspect the MC
reservoir valve isn't sealing well allowing some of the stroke output to
simply go back to the reservoir.

I expect I could fabricate a better MC setup and add a bit more
displacement as well since I've always felt it bordered on not enough
displacement.
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.

Normal pedal bleeding, depress, open bleeder, close bleeder, release
pedal, repeat... over and over and over.

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.


When you pump the pedal is the effort different than when the clutch
does work?

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.

Could be that the piston has a small tear or defect that prevents a seal.


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.

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.


--
Steve W.

"Steve W." wrote:

Pete C. wrote:
"Steve W." wrote:
Pete C. wrote:
"Steve W." wrote:
Pete C. wrote:
No grinding or anything, just continual clutch no-release problems.
Clutch replaced once, coaxial slave cylinder replaced another time, MCs
replaced like four times. Never had a problem with clutch slip, only
failure to release.

Now that I have a new truck, I'm getting ready to pull the clutch on the
old one myself and see if I can fix it for good. This truck also ate
rear axle seals until I got into it. Axles seals replaced under warranty
several times, when they went again out of warranty I replaced them
myself and haven't had a problem since (195k+ now).
Step down and no release?
Yep, makes it kinds difficult to shift. Bit of a problem when you need
to stop as well.

If you step down a second time does it release
then?
Nope, pump it a half dozen times and you might get it to release enough
to shift with a clunk. Doesn't do it all the time either, can be working
just fine then start acting up.

I have no good way to monitor it for testing, but I suspect the MC
reservoir valve isn't sealing well allowing some of the stroke output to
simply go back to the reservoir.

I expect I could fabricate a better MC setup and add a bit more
displacement as well since I've always felt it bordered on not enough
displacement.
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.

Normal pedal bleeding, depress, open bleeder, close bleeder, release
pedal, repeat... over and over and over.

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.

Unfortunately I need to get a rebuild kit for my Mighty-Vac.



When you pump the pedal is the effort different than when the clutch
does work?

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.

Could be that the piston has a small tear or defect that prevents a seal.

On four or five different MCs? Design flaw is my take on it.



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.

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.

--
Steve W.

On Tue, 21 Jul 2009 12:03:46 -0500, Tim Wescott wrote:

I'll ask my _second_ question _first_, so you can think about it while
you read my first question: What's a good newsgroup to post this sort of
question? I hate fora, so if there's an active newsgroup that'd be
vastly preferred.

My _first_ question is: are all clutch master cylinders created equal?

I'm putting a 2.8L V-6 into a Vega (to be followed by a 3.4L V-6 from GM
Performance Parts, if they survive the bankruptcy). I'm doing this
instead of a small block V-8 because I'm crazy, because the 2.8 block
lets be get at the spark plugs without jacking the motor up, and because
it'll help retain a halfway decent balance fore and aft (I hope).

Because I'm crazy I'm retaining the stick shift of the original, so I
need a clutch linkage. The transmission that fits well is from an '87
Camero (with 2.8L V-6), but it wants a hydraulic clutch instead of the
cable clutch which came on the Vega and the S-10 that donated the
engine.

For a variety of reasons (mostly having to do with the advisability of
welding on unknown alloy cast aluminum) I don't want to modify the
Camero bellhousing. The S-10 bellhousing won't fit.

So I'm planning on finding the correct Camero clutch slave cylinder
parts that'll just bolt onto the bellhousing, but that leaves me with
needing to get the master cylinder mounted onto the firewall. I already
know it'll be a bitch; I'm planning on getting all of the Camero parts I
can (both pushrods, both cylinders, even bolts and tubing if I can).
But if the Camero master cylinder just won't fit, how much leeway do I
have in finding something that will? Do I get just any old thing? Is
there an interchange book that's accessible? Are different master
cylinders with different bores readily available, and how much can I
compensate for differing pedal-to-pushrod mechanical advantages by
changing the master cylinder bore? Are there any other differences I
need to know (surely there are some valving issues -- anything else?).

TIA.

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).

--
www.wescottdesign.com

wrote:
On Wed, 22 Jul 2009 08:17:23 -0500, "Pete C."
wrote:

wrote:
On Tue, 21 Jul 2009 22:11:38 -0500, "Pete C."
wrote:

wrote:
On Tue, 21 Jul 2009 17:54:04 -0500, "Pete C."
wrote:

"Steve W." wrote:
Pete C. wrote:
No grinding or anything, just continual clutch no-release problems.
Clutch replaced once, coaxial slave cylinder replaced another time, MCs
replaced like four times. Never had a problem with clutch slip, only
failure to release.

Now that I have a new truck, I'm getting ready to pull the clutch on the
old one myself and see if I can fix it for good. This truck also ate
rear axle seals until I got into it. Axles seals replaced under warranty
several times, when they went again out of warranty I replaced them
myself and haven't had a problem since (195k+ now).
Step down and no release?
Yep, makes it kinds difficult to shift. Bit of a problem when you need
to stop as well.

If you step down a second time does it release
then?
Nope, pump it a half dozen times and you might get it to release enough
to shift with a clunk. Doesn't do it all the time either, can be working
just fine then start acting up.

I have no good way to monitor it for testing, but I suspect the MC
reservoir valve isn't sealing well allowing some of the stroke output to
simply go back to the reservoir.

I expect I could fabricate a better MC setup and add a bit more
displacement as well since I've always felt it bordered on not enough
displacement.
How close is the fluid line to a manifold?
Not particularly close, probably 6" from the manifold, 3" from the pipe
heading down to where it crosses under the clutch bellhousing.

How old is the fluid?
A month or so since I last replaced the MC and flushed a good pint
through and out the coaxial slave cylinder breather.

Sure
sounds like vapour fade due to inferior fluid or overheated lines.
Sounds like it, and some of the cases of it acting up have been after
it's had some time to heat up, but other have been acting up from cold.

I suppose I could find some insulating wrap and wrap the line. Not sure
on inferior fluid, it just uses DOT3 brake fluid. The last couple pints
have just been generic DOT3, is there a particular brand I should look
for?
DON"T use heat wrap - use a properly positioned heat sheild and you
should be using DOT4 fluid, not DOT3.. The best heat sheild is a
stainless steel sheet midway between the heat source and the tube - or
half of a 2" stainless steel tube mounted so it semi-surrounds the
tubeing, about 1" from the tubing.. Three inches from the crossover
without a heat sheild is TOO CLOSE.
Might get by with DOT4 or DOT5 fluid, but you are still pushing it.
I'll see what I can find to fab a shield. What about heat wrap on the
pipe where it crosses under?

If I change to a DOT4 or DOT5 fluid what kind of cleaning would I have
to do and would there be seal material compatibility issues? Brands of
fluid to look for?
DOT4 is a direct compatible replacement. Dot5 requires a flush -
generally alchohol or BrakeKlean.

I'd go with Dot4 for simplicity.
Heat wrap causes premature pipe failure.

there is now a DOT 5.1 that is another breed altogether.
Apparently it's non-silicone and has some compatibility with other types.

www.stoptech.com

DOT 5.1 fluids!

Historically, DOT 5-level performance (specifically boiling points and
viscosity) could only be achieved with silicone-based fluids. However,
modern compounding has created glycol ether-based fluids which now meet
DOT 5 bogeys in these key areas. Consequently, the DOT 5.1 moniker was
created to differentiate between these two very different chemistries
which both meet DOT 5 performance requirements.

In so many words, DOT 5.1 fluids are simply DOT 4-type fluids which meet
DOT 5 performance requirements. Because of this, they typically can be
mixed with DOT 3 or DOT 4 fluids without concern. In some circles, they
are even referred to as ‘DOT 4 Plus’ or ‘Super DOT 4’ fluids because
they are more similar to a conventional DOT 4 fluid by chemistry than
they are to a conventional DOT 5 fluid. In fact, DOT 5.1 is essentially
comprised of Borate Esters.

While it may not be obvious, the big advantage of the DOT 5.1 fluids is
that they contain all of the nifty water-absorbing characteristics of
the DOT 3 and DOT 4 fluids while simultaneously providing for very high
boiling points and relatively stable viscosity over a wide range of
temperatures. The best of all worlds, you could say. The table below
sums it up quite nicely.
PROPERTY DOT 4 DOT 5 DOT 5.1
Dry BP (F)@ 0.0% H2O 446 509 509
Wet BP (F)@ 3.7% H2O 311 356 356
Chemical Composition Glycol Ether / Borate Ester Silicone Based
Glycol Ether / Borate Ester

(As stated earlier, the table data above contains the minimum properties
for a fluid to be called a certain type. For example there are many
racing brake fluids with Dry BP performance at or above 590o F and Wet
BP at or above 390o F.)

So, what is the downside of the DOT 5.1 fluids? Like most things in
life, the good stuff isn’t cheap. DOT 5.1 fluids typically cost three to
four times as much to manufacture as a conventional DOT 4 fluids.
There’s always a catch…

RBnDFW wrote:

wrote:
On Wed, 22 Jul 2009 08:17:23 -0500, "Pete C."
wrote:

wrote:
On Tue, 21 Jul 2009 22:11:38 -0500, "Pete C."
wrote:

wrote:
On Tue, 21 Jul 2009 17:54:04 -0500, "Pete C."
wrote:

"Steve W." wrote:
Pete C. wrote:
No grinding or anything, just continual clutch no-release problems.
Clutch replaced once, coaxial slave cylinder replaced another time, MCs
replaced like four times. Never had a problem with clutch slip, only
failure to release.

Now that I have a new truck, I'm getting ready to pull the clutch on the
old one myself and see if I can fix it for good. This truck also ate
rear axle seals until I got into it. Axles seals replaced under warranty
several times, when they went again out of warranty I replaced them
myself and haven't had a problem since (195k+ now).
Step down and no release?
Yep, makes it kinds difficult to shift. Bit of a problem when you need
to stop as well.

If you step down a second time does it release
then?
Nope, pump it a half dozen times and you might get it to release enough
to shift with a clunk. Doesn't do it all the time either, can be working
just fine then start acting up.

I have no good way to monitor it for testing, but I suspect the MC
reservoir valve isn't sealing well allowing some of the stroke output to
simply go back to the reservoir.

I expect I could fabricate a better MC setup and add a bit more
displacement as well since I've always felt it bordered on not enough
displacement.
How close is the fluid line to a manifold?
Not particularly close, probably 6" from the manifold, 3" from the pipe
heading down to where it crosses under the clutch bellhousing.

How old is the fluid?
A month or so since I last replaced the MC and flushed a good pint
through and out the coaxial slave cylinder breather.

Sure
sounds like vapour fade due to inferior fluid or overheated lines.
Sounds like it, and some of the cases of it acting up have been after
it's had some time to heat up, but other have been acting up from cold.

I suppose I could find some insulating wrap and wrap the line. Not sure
on inferior fluid, it just uses DOT3 brake fluid. The last couple pints
have just been generic DOT3, is there a particular brand I should look
for?
DON"T use heat wrap - use a properly positioned heat sheild and you
should be using DOT4 fluid, not DOT3.. The best heat sheild is a
stainless steel sheet midway between the heat source and the tube - or
half of a 2" stainless steel tube mounted so it semi-surrounds the
tubeing, about 1" from the tubing.. Three inches from the crossover
without a heat sheild is TOO CLOSE.
Might get by with DOT4 or DOT5 fluid, but you are still pushing it.
I'll see what I can find to fab a shield. What about heat wrap on the
pipe where it crosses under?

If I change to a DOT4 or DOT5 fluid what kind of cleaning would I have
to do and would there be seal material compatibility issues? Brands of
fluid to look for?
DOT4 is a direct compatible replacement. Dot5 requires a flush -
generally alchohol or BrakeKlean.

I'd go with Dot4 for simplicity.
Heat wrap causes premature pipe failure.

there is now a DOT 5.1 that is another breed altogether.
Apparently it's non-silicone and has some compatibility with other types.

www.stoptech.com

DOT 5.1 fluids!

Historically, DOT 5-level performance (specifically boiling points and
viscosity) could only be achieved with silicone-based fluids. However,
modern compounding has created glycol ether-based fluids which now meet
DOT 5 bogeys in these key areas. Consequently, the DOT 5.1 moniker was
created to differentiate between these two very different chemistries
which both meet DOT 5 performance requirements.

In so many words, DOT 5.1 fluids are simply DOT 4-type fluids which meet
DOT 5 performance requirements. Because of this, they typically can be
mixed with DOT 3 or DOT 4 fluids without concern. In some circles, they
are even referred to as ‘DOT 4 Plus’ or ‘Super DOT 4’ fluids because
they are more similar to a conventional DOT 4 fluid by chemistry than
they are to a conventional DOT 5 fluid. In fact, DOT 5.1 is essentially
comprised of Borate Esters.

While it may not be obvious, the big advantage of the DOT 5.1 fluids is
that they contain all of the nifty water-absorbing characteristics of
the DOT 3 and DOT 4 fluids while simultaneously providing for very high
boiling points and relatively stable viscosity over a wide range of
temperatures. The best of all worlds, you could say. The table below
sums it up quite nicely.
PROPERTY DOT 4 DOT 5 DOT 5.1
Dry BP (F)@ 0.0% H2O 446 509 509
Wet BP (F)@ 3.7% H2O 311 356 356
Chemical Composition Glycol Ether / Borate Ester Silicone Based
Glycol Ether / Borate Ester

(As stated earlier, the table data above contains the minimum properties
for a fluid to be called a certain type. For example there are many
racing brake fluids with Dry BP performance at or above 590o F and Wet
BP at or above 390o F.)

So, what is the downside of the DOT 5.1 fluids? Like most things in
life, the good stuff isn’t cheap. DOT 5.1 fluids typically cost three to
four times as much to manufacture as a conventional DOT 4 fluids.
There’s always a catch…

Given the small quantities used, I would expect the cost difference is
pretty negligible.

Pete C. wrote:
RBnDFW wrote:
wrote:
On Wed, 22 Jul 2009 08:17:23 -0500, "Pete C."
wrote:

wrote:
On Tue, 21 Jul 2009 22:11:38 -0500, "Pete C."
wrote:

wrote:
On Tue, 21 Jul 2009 17:54:04 -0500, "Pete C."
wrote:

"Steve W." wrote:
Pete C. wrote:
No grinding or anything, just continual clutch no-release problems.
Clutch replaced once, coaxial slave cylinder replaced another time, MCs
replaced like four times. Never had a problem with clutch slip, only
failure to release.

Now that I have a new truck, I'm getting ready to pull the clutch on the
old one myself and see if I can fix it for good. This truck also ate
rear axle seals until I got into it. Axles seals replaced under warranty
several times, when they went again out of warranty I replaced them
myself and haven't had a problem since (195k+ now).
Step down and no release?
Yep, makes it kinds difficult to shift. Bit of a problem when you need
to stop as well.

If you step down a second time does it release
then?
Nope, pump it a half dozen times and you might get it to release enough
to shift with a clunk. Doesn't do it all the time either, can be working
just fine then start acting up.

I have no good way to monitor it for testing, but I suspect the MC
reservoir valve isn't sealing well allowing some of the stroke output to
simply go back to the reservoir.

I expect I could fabricate a better MC setup and add a bit more
displacement as well since I've always felt it bordered on not enough
displacement.
How close is the fluid line to a manifold?
Not particularly close, probably 6" from the manifold, 3" from the pipe
heading down to where it crosses under the clutch bellhousing.

How old is the fluid?
A month or so since I last replaced the MC and flushed a good pint
through and out the coaxial slave cylinder breather.

Sure
sounds like vapour fade due to inferior fluid or overheated lines.
Sounds like it, and some of the cases of it acting up have been after
it's had some time to heat up, but other have been acting up from cold.

I suppose I could find some insulating wrap and wrap the line. Not sure
on inferior fluid, it just uses DOT3 brake fluid. The last couple pints
have just been generic DOT3, is there a particular brand I should look
for?
DON"T use heat wrap - use a properly positioned heat sheild and you
should be using DOT4 fluid, not DOT3.. The best heat sheild is a
stainless steel sheet midway between the heat source and the tube - or
half of a 2" stainless steel tube mounted so it semi-surrounds the
tubeing, about 1" from the tubing.. Three inches from the crossover
without a heat sheild is TOO CLOSE.
Might get by with DOT4 or DOT5 fluid, but you are still pushing it.
I'll see what I can find to fab a shield. What about heat wrap on the
pipe where it crosses under?

If I change to a DOT4 or DOT5 fluid what kind of cleaning would I have
to do and would there be seal material compatibility issues? Brands of
fluid to look for?
DOT4 is a direct compatible replacement. Dot5 requires a flush -
generally alchohol or BrakeKlean.

I'd go with Dot4 for simplicity.
Heat wrap causes premature pipe failure.
there is now a DOT 5.1 that is another breed altogether.
Apparently it's non-silicone and has some compatibility with other types.

www.stoptech.com

DOT 5.1 fluids!

Historically, DOT 5-level performance (specifically boiling points and
viscosity) could only be achieved with silicone-based fluids. However,
modern compounding has created glycol ether-based fluids which now meet
DOT 5 bogeys in these key areas. Consequently, the DOT 5.1 moniker was
created to differentiate between these two very different chemistries
which both meet DOT 5 performance requirements.

In so many words, DOT 5.1 fluids are simply DOT 4-type fluids which meet
DOT 5 performance requirements. Because of this, they typically can be
mixed with DOT 3 or DOT 4 fluids without concern. In some circles, they
are even referred to as ‘DOT 4 Plus’ or ‘Super DOT 4’ fluids because
they are more similar to a conventional DOT 4 fluid by chemistry than
they are to a conventional DOT 5 fluid. In fact, DOT 5.1 is essentially
comprised of Borate Esters.

While it may not be obvious, the big advantage of the DOT 5.1 fluids is
that they contain all of the nifty water-absorbing characteristics of
the DOT 3 and DOT 4 fluids while simultaneously providing for very high
boiling points and relatively stable viscosity over a wide range of
temperatures. The best of all worlds, you could say. The table below
sums it up quite nicely.
PROPERTY DOT 4 DOT 5 DOT 5.1
Dry BP (F)@ 0.0% H2O 446 509 509
Wet BP (F)@ 3.7% H2O 311 356 356
Chemical Composition Glycol Ether / Borate Ester Silicone Based
Glycol Ether / Borate Ester

(As stated earlier, the table data above contains the minimum properties
for a fluid to be called a certain type. For example there are many
racing brake fluids with Dry BP performance at or above 590o F and Wet
BP at or above 390o F.)

So, what is the downside of the DOT 5.1 fluids? Like most things in
life, the good stuff isn’t cheap. DOT 5.1 fluids typically cost three to
four times as much to manufacture as a conventional DOT 4 fluids.
There’s always a catch…

Given the small quantities used, I would expect the cost difference is
pretty negligible.

Agreed.
I have used Dot 5 in the past for my project vehicles.
I'll probably use DOT 5.1 in some now.