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Clutch Master Cylinders 
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Joined: Thu Mar 06, 2008 1:47 pm
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Location: West Midlands
Post Clutch Master Cylinders
Can either a metal or plastic clutch master cylinders be fitted or is there a difference in height


Mon May 19, 2008 1:48 pm
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Post Re: Clutch Master Cylinders
As far as I know they're the same height but I wouldn't trust me if I were you. I'm the one that had to make a bonnet bulge to get clearance for the master cylinders even when the originals seemed to fit fine.

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Mon May 19, 2008 4:35 pm
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Post Re: Clutch Master Cylinders
Was that with fitting the original ones back in - as i have noticed that the ones of the one i have have been rubbing on the bonet


Mon May 19, 2008 7:35 pm
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Post Re: Clutch Master Cylinders
I fitted the plastic reservoir cylinders during the rebuild but even with low line banjo fittings for the plumbing I still had to make a bulge to clear the cylinders.
I still don't know why.
Somebody must have moved something when I wasn't looking. I measured everything ever so carefully too.

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Tue May 20, 2008 6:43 pm
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Post Re: Clutch Master Cylinders
Has anyone found a cure to a heavy clutch pedal, I remember my race mini having a heavy pedal but nothing like the Coupe one, I know the pedals have be reduced in length effectively making the ratio different but with the grey diaphram and paddle clutch plate its a monster. Any suggestions,

I was thinking of using a remote master cylinder with a smaller bore say .625"????


Thu Jul 24, 2008 1:26 pm
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The Terrible Tims

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Post Re: Clutch Master Cylinders
I'm going to be using 1/4" pipe to run the length of the car, rather than the standard brake pipe. I think a proportion of the heavy pedal is the fluid dragging in the pipe.

If you are using 3/16", then it may be worth a try to reduce the effort.

I'm fitting a grey diaphragm, so I'll need all the help I can get!

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Thu Jul 24, 2008 1:35 pm
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Post Re: Clutch Master Cylinders
I swapped a tin master for a plastic one at Avon Park - no difference in height as far as I could see.

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Thu Jul 24, 2008 3:15 pm
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Post Re: Clutch Master Cylinders
Andy wrote:
Has anyone found a cure to a heavy clutch pedal, ..

Did you set the clutch up properly when you built it?
It makes a tremendous difference, we're running an Orange plate in my sons S and it's lighter than the un-setup std. plate he had before.

Quote:
..I was thinking of using a remote master cylinder with a smaller bore say .625"????

Well that would give a lighter pedal of course but could you cater for the longer throw?

I think Tim's suggestion of bigger piping is also a good point.


Thu Jul 24, 2008 5:44 pm
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Post Re: Clutch Master Cylinders
The pipe bore really won't make that much difference.

If all the mechanical pivots are moving freely then the pressure needed depends on the strength of the clutch pressure plate, the length of the clutch pedal and the relative diameters (piston areas) of the master and slave cylinders.

If you use a smaller master cylinder you will need less pedal force but more pedal travel will be needed to fully separate the clutch.

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Thu Jul 24, 2008 8:15 pm
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Post Re: Clutch Master Cylinders
I use a Grey on my engine not sure if it makes any odds but it always seems to get easier as the engine warms up :shock: :lol:

The clutch line runs close to the water pipes :?:

You get use to it being stiff tho

Ooo err :shock:

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Thu Jul 24, 2008 10:05 pm
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Post Re: Clutch Master Cylinders
Yeah the clutch is setup properly, and there is a significent difference between the orange and the grey, I'm not to fussed about it but you wouldn't want to be sitting in a traffic jam for too long, I'm going to try the smaller ID cylinder, there is plenty of room for pedal travel. A can't see the larger pipes making the clutch any easier to opperate, as someone said its all to do with the pivot points and relative pressure created between the master and slave combo. My wife struggles to depress the clutch so I'm trying to compromise between the two. If I keep her happy then I get more money to spen on the car!!!!!


Fri Jul 25, 2008 8:46 am
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Post Re: Clutch Master Cylinders
Isn't a lot of it to do with the angle of dangle of the pedal itself?

Mine feels a bit stiff because of the direction of push onto the pedal is far from ideal - again Ooo err!!

I'd have thought that at the speed the fluid travels down the pipe the losses would be minimal.

A decent braided flexi instead of the standard rubber will help a little. Ensuring everything pivot wise on the clutch actuation is adjusted correctly, moving freely, clean and properly greased will also help.

Also check the alignment of the clutch pedal pivot to the master cylinder. A slight misalignment would cause (Theoretically) a good bit more force required.

If you re-drilled the pivot point on the pedal to master slightly closer to the pedal main pivot it'd have the same effect as reducing the bore of the master - as long as you could keep the alignment.

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Fri Jul 25, 2008 10:13 am
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Post Re: Clutch Master Cylinders
also worth noting,

USe the shortest braided lines possible so there is less compliance in the system, a flexible hoe expands a littel under pressure unlike a solid line. thinking of changing a couple of my braided hoses as they are a little long.

I prob have the heaviest clutch :lol: :shock: as when i drove stuarts the other year it was sooo liight compared to mine and thats a gray :lol: but mine is far from the standard

the key is nice free moving linkages and good ratios/arcs, and the minimal flex in the system,

if you want a really small master cylinder there is a 14mm one available from ap, but is not cheap

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Fri Jul 25, 2008 1:00 pm
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Post Re: Clutch Master Cylinders
The flex (expansion) you will get in braided line is miniscale and not worth worrying about. I would keep the braided line as it is far stronger than the copper equlivant. I'm going to have a look to see if I can increase the lever ratio at the pedal box first but if that doesn't work I will be changing the master cylinder. I'm also going to change the angle of the pedal as its not the most user friendly. West why is yours so heavy??? Aren't you running a Honda engine??? I wouldn't have thought it would be as bad as a grey + diaphram.


Fri Jul 25, 2008 2:56 pm
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The Terrible Tims
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Post Re: Clutch Master Cylinders
Anyone considered a concentric slave cylinder in a mini :?:

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Fri Jul 25, 2008 5:43 pm
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