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 Posted: Feb 23, 2018 05:44AM
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CA
Quote:
Originally Posted by Alex

Wear in any part of the assembly - pedal hole, clevis pin, or pushrod yoke - will affect it in the same manner as raising the master cylinder with thicker components, but to put it in basic principles to get the idea across we forget about it.

It's a bit like taking gravity as 10 m/s/s instead of 9.81 m/s/s to make things easier while learning about acceleration.

So, what you are saying is that a Mini will fall just as fast as any other car. Take that Ferrari.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Feb 23, 2018 05:21AM
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That's it, an adjustable master push rod, then do some testing. Just need warmer weather.

 Posted: Feb 22, 2018 11:36PM
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GB

Wear in any part of the assembly - pedal hole, clevis pin, or pushrod yoke - will affect it in the same manner as raising the master cylinder with thicker components, but to put it in basic principles to get the idea across we forget about it.

It's a bit like taking gravity as 10 m/s/s instead of 9.81 m/s/s to make things easier while learning about acceleration.

 Posted: Feb 22, 2018 08:29PM
 Edited:  Feb 22, 2018 08:34PM
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Quote:
Originally Posted by Alex

Forget slack in the linkages.

The clutch pedal is held in the up position by the master cylinder sitting on its bottom stop - unconnected the pedal will spring up and nigh-on touch the dashboard.

If the master cylinder is raised vertically by means of a thicker gasket and/or a thicker baseplate, the pedal will naturally sit closer to the floor.

As the pedal is closer to the floor before you depress it, it has a shorter distance to travel before it hits the floor and therefore displaces less fluid to the slave.  

I suspect this is what i have inadvertantly done, as the clutch is sooo neeeearly disengaging but crunches if you're not super careful.

I don't buy that argument either.... (re slack in linkages being irrelevant)

If the master piston is stopping the pedal moving up (if.....well it obviously is  then the master push rod linkage is in tension.  When you press the pedal down the master push rod linkage moves into compression.  Any wear in the master clevis pin or its holes shows as lost motion as the linkage moves from tension to compression.  Lost motion means the pedal moves down some distance before the piston starts moving.  

Ie ..you've used up some of your pedal travel with no useful motion passed to the release bearing..... 

I hadn't fully thought out the implications of the master piston always sitting on the bottom of the cylinder (even though the workshop manual shows this).

So it would appear that the solution is not to add gaskets but to remove them (not forgetting the metal plate ... but noting that on RHD cars this is also the engine steady anchor) .... or maybe lengthening the master push rod ..but maybe I already suggested that....

Cheers, Ian

Shouldn't be too smug ... Was suggesting it for the wrong reason

 Posted: Feb 22, 2018 06:46PM
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Finally, someone comes up with a new to me idea about why my clutch pedal has to nearly go to the floor before the clutch releases! I'll go look at my master cylinder right now. But just before I do I'll tell you all that I adjust the small stop bolt to .005" to maximize clutch pedal throw. Does anyone have a nominal gasket thickness?

'72 Morris Mini - 1310cc, K1100 head conversion

 

 

 

 Posted: Feb 22, 2018 03:04PM
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GB

Forget slack in the linkages.

The clutch pedal is held in the up position by the master cylinder sitting on its bottom stop - unconnected the pedal will spring up and nigh-on touch the dashboard.

If the master cylinder is raised vertically by means of a thicker gasket and/or a thicker baseplate, the pedal will naturally sit closer to the floor.

As the pedal is closer to the floor before you depress it, it has a shorter distance to travel before it hits the floor and therefore displaces less fluid to the slave.  

I suspect this is what i have inadvertantly done, as the clutch is sooo neeeearly disengaging but crunches if you're not super careful.

 Posted: Feb 22, 2018 01:50PM
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Quote:
Originally Posted by Dan Moffet
Quote:
Originally Posted by 1963SV2
Quote:
Originally Posted by Rosebud
Quote:
Originally Posted by Alex
Quote:

Wonder if I've raised the master cylinder too high which is why I've got release issues on the raceweight flywheel/clutch assembly ?
Assuming that increasing the gasket thickness would increase the travel of the cylinder thus decreasing the throw of the clutch arm, then yeah. Makes sense to me.
Can you explain how/why?????

cheers, ian
Increasing the gasket would reduce the movement IN the master cylinder because it increases the distance and slack between the pedal and the bottom end of the master cylinder piston. The only way adding a gasket would improve m/c piston travel would be if there was no slack at all, resulting in the pedal not allowing the piston to return fully, limiting the total travel. Like engine valves, there is a need for some slack (= valve lash) for things to work properly.
I don't think I buy that argument..  Piston travel is independent of the cylinder itself - unless the pistons sits on the bottom of the cylinder.  If this happens then lifting the cylinder will actually pull the pedal down thereby reducing travel.  

If the piston is not bottoming out then its travel is determined by the top and bottom (pedal hits floor) od pedal travel.

AIUI (and would much appreciate guidance if I'm not thinking this right) What is important is "effective" piston travel.  Inside the cylinder is a port that allows fluid to travel between the cylinder and the fluid reservoir (the tin can).  As you press the pedal the piston rises and pushes fluid out of the cylinder into the reservoir.  The clutch diaphragm is the load that stops fluid moving towards  the slave while it can otherwise escape freely into the reservoir..... disregarding any wear/slop that allows the pedal to travel before the piston starts to move..... As pedal travel continues, this port is closed as the main cup moves past it.  Further pedal travel now pushes fluid down to the slave and at this point the clutch starts to release (again assuming no slop in the linkages).  The "effective" piston travel is the distance from the top of the port to the top of piston travel.

This gets smaller as you lift the cylinder ....by adding gaskets under it.

Extra gaskets are only a benefit if the "as assembled" arrangement sees the transfer port below the lip of the seal....

Discuss...  

Cheers, Ian

 Posted: Feb 22, 2018 05:05AM
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CA
Quote:
Originally Posted by 1963SV2
Quote:
Originally Posted by Rosebud
Quote:
Originally Posted by Alex
Quote:

Wonder if I've raised the master cylinder too high which is why I've got release issues on the raceweight flywheel/clutch assembly ?
Assuming that increasing the gasket thickness would increase the travel of the cylinder thus decreasing the throw of the clutch arm, then yeah. Makes sense to me.
Can you explain how/why?????

cheers, ian
Increasing the gasket would reduce the movement IN the master cylinder because it increases the distance and slack between the pedal and the bottom end of the master cylinder piston. The only way adding a gasket would improve m/c piston travel would be if there was no slack at all, resulting in the pedal not allowing the piston to return fully, limiting the total travel. Like engine valves, there is a need for some slack (= valve lash) for things to work properly.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Feb 22, 2018 03:46AM
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Quote:
Originally Posted by Rosebud
Quote:
Originally Posted by Alex
Quote:

Wonder if I've raised the master cylinder too high which is why I've got release issues on the raceweight flywheel/clutch assembly ?
Assuming that increasing the gasket thickness would increase the travel of the cylinder thus decreasing the throw of the clutch arm, then yeah. Makes sense to me.
Can you explain how/why?????

cheers, ian

 Posted: Feb 21, 2018 07:03AM
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US
Did you really think I'd be that easy? Thinking is required on the under master gasket. I ordered a bag of them from MSC and they are a hard paper/fabric material about 1/8 thick. If for some reason the master piston is pushed in without the spacer then there would be more travel, I don't see it that way and have come up with my own solution. I aim for release at half travel or slightly less. You know when removing carpet and sound deadening and get release before the floor what has to be done. Steve (CTR)

 Posted: Feb 20, 2018 08:37PM
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Quote:
Originally Posted by minimans

Quote:
Increasing the travel of the master would increase the travel of the slave??
No, increasing the travel of the master would decrease the travel of the slave.

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports

 Posted: Feb 20, 2018 08:35PM
 Edited:  Feb 20, 2018 08:50PM
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Quote:
Originally Posted by Dan Moffet
Quote:

What I think he meant was increasing the gasket thickness would increase the pedal travel to actuate the master (AKA more slack) which would reduce the effective movement of the slave, arm etc.
Yeah, that's what I meant. So, is this true? Simple way to get more peddle play, which seems to be a common problem. If I understand Alex correctly, it sounds like he may have overdone it a bit.

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports

 Posted: Feb 20, 2018 05:28PM
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CA
Quote:
Originally Posted by minimans
Quote:
Originally Posted by Rosebud
Quote:
Originally Posted by Alex
Quote:

Wonder if I've raised the master cylinder too high which is why I've got release issues on the raceweight flywheel/clutch assembly ?
Assuming that increasing the gasket thickness would increase the travel of the cylinder thus decreasing the throw of the clutch arm, then yeah. Makes sense to me.
Increasing the travel of the master would increase the travel of the slave??
What I think he meant was increasing the gasket thickness would increase the pedal travel to actuate the master (AKA more slack) which would reduce the effective movement of the slave, arm etc.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Feb 20, 2018 05:16PM
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Quote:
Originally Posted by Rosebud
Quote:
Originally Posted by Alex
Quote:

Wonder if I've raised the master cylinder too high which is why I've got release issues on the raceweight flywheel/clutch assembly ?
Assuming that increasing the gasket thickness would increase the travel of the cylinder thus decreasing the throw of the clutch arm, then yeah. Makes sense to me.
Increasing the travel of the master would increase the travel of the slave??

Mini's are like buses they come along in a bunch

 Posted: Feb 20, 2018 05:13PM
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CA
Quote:
Originally Posted by Rosebud
Quote:
Originally Posted by Alex
Quote:

Wonder if I've raised the master cylinder too high which is why I've got release issues on the raceweight flywheel/clutch assembly ?
Assuming that increasing the gasket thickness would increase the travel of the cylinder thus decreasing the throw of the clutch arm, then yeah. Makes sense to me.
+1

.

"Hang on a minute lads....I've got a great idea."

 Posted: Feb 20, 2018 04:36PM
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US
Quote:
Originally Posted by Alex
Quote:

Wonder if I've raised the master cylinder too high which is why I've got release issues on the raceweight flywheel/clutch assembly ?
Assuming that increasing the gasket thickness would increase the travel of the cylinder thus decreasing the throw of the clutch arm, then yeah. Makes sense to me.

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports

 Posted: Feb 20, 2018 02:58PM
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GB
Quote:
Originally Posted by onetim
There is a gasket called for under the master, and it's fairly thick.
Lightbulb moment.

The standard gasket under the master cylinder and engine steady plate is actually really thin, I've replaced one of mine with the DSN cover and a pretty cork gasket that I cut out...  Wonder if I've raised the master cylinder too high which is why I've got release issues on the raceweight flywheel/clutch assembly ?

 Posted: Feb 19, 2018 08:38PM
 Edited:  Feb 19, 2018 08:47PM
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US
Quote:
Originally Posted by Dan Moffet

...I believe he was asking about the small bolt that holds the clutch lever out to remove excess slack.
Correct. I was in fact asking about the clutch return arm stop. But now I'm curious about...

Quote:
Originally Posted by CooperTune

...I also do something else I won't share here. 

Just what was it that you did, Steve? 

 

Michael, Santa Barbara, CA

. . . the sled, not the flower

      Poser MotorSports

 Posted: Feb 19, 2018 06:29AM
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There is a gasket called for under the master, and it's fairly thick.

 Posted: Feb 19, 2018 05:56AM
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Seems I recall having this topic come up while Jemal was still around. He claimed putting the spacer under the clutch master would improve the pedal throw issue. If I have replaced all parts in the clutch system ( and I mean all parts ) and have a very low release point, I remove the clutch pedal check the clevis bore ( weld it up drill and ream it to size ) I also do something else I won't share here. 

As for the over throw nuts, I bought a old open end wrench the right size and ground it down to the correct thickness so I can truly jamb the nuts together. I know some people just saw the threaded part off and go on. Steve (CTR) 

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