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Discussion Starter · #1 · (Edited)
I am interested in peoples experience with the size of the M/C they have used. The standard Dodge one is 7/8" , has anyone got away with a 3/4" M/C and with a 13" clutch do you need a 1" M/C? or has someone had experience with a different size. Basically what works & what doesn't.

Gaza
 

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Discussion Starter · #3 · (Edited)
CrewCab59 I looked on rockauto's web site and all the clutch's for the fords you mention are 7/8" is this correct? this is the same size as the Dodge ones. The cheapest one was a Raybestos item for $38. Which ones have you had. What connector do these clutch masters have?

Gaza
 

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The ford master that I listed is a 7/8 bore and dodge 94 up .The line is the same as well,I just have my line made to length that I need.

The Gm master is 17mm,just not enough bore to push the SBC,and it bolts up insame location.

Take a look a J10 conversion that I did ,you'll see the master and line set up.

Thanks
CrewCa59
 

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Take a look at a hydraulic bottle jack: there's a very small pump cylinder at the handle, and a much larger slave cylinder at the ram section. If these two were equal there would be no hydraulic advantage. The greater the difference in size between the two, with the master being smaller than the slave, the greater the hydraulic advantage.

Small bore master, easy pedal effort; large bore master, hard pedal effort. It's backwards from what we want to think! Note that a slave cylinder is usually a shorter ram section, and larger in diameter than master. Master's longer stroke and smaller diameter allows the ease of clutch disengagement while still providing sufficient fluid to do the job.
 

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Discussion Starter · #6 ·
My master cylinder is 3/4"(19mm) which is bang in the middle of the 2 that CrewCab59 has mentioned, not sure here but I think it needs to move the slave a min of 1" to operate clutch properly so it seems to have more to do with volume. If my wife drove my camper I would be concerned about increased pedal pressure but she wont so as long as it can shift enough fluid I will be happy. The MC I have is easily available and very cheap everywhere in England if it works I will be very happy, if not I will sharp order a couple of MCs from the states that CrewCab59 recomended. I am finding it almost impossible to find a MC larger than 3/4" here. Would a Brake MC be OK? fluid is just fluid. on the other hand they are usually split and I would probably be guessing and getting a known one from the states that works is still quite cheap. I should soon be at the point where I will find out.

Gaza
 

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The only American vehicles with a single reservoir master cylinder will be pre-1967. A Federal Law mandated that all brake masters be dual chamber reservoir in '67 and beyond.

The main difference between a clutch master and a brake master, when they're similar bore diameter, is bore depth. A brake master usually has a deeper bore so it moves a larger volume of fluid. You can still get '60's Dodge truck single clutch master cylinders, or brake masters. The hot ticket is to get the right one then have it lined with brass or stainless steel as a lifetime master cylinder. Stock up on a few rebuild kits and never have to worry about it again! I can provide a link for a man that relines masters with stainless over here.
 
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