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Slave Cylinder Help

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Old May 31, 2019 | 09:39 AM
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Slave Cylinder Help

Also posted to the clutch/transmission sub forum.

Good morning,

I'm adding a hydraulic clutch setup to my vehicle and am using a slave cylinder from a 1966 P 350... can anyone tell me the line fitting thread size going into this slave cylinder? Coming from the master it's a standard 3/16ths line and fitting, but on the back of the slave it's larger. I'd love to just bring it to NAPA and try different sizes, but it's a bit stuck in place now... don't ask.

Thanks!

 
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Old May 31, 2019 | 02:39 PM
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Originally Posted by RattyFord

I'm adding a hydraulic clutch setup to my vehicle and am using a slave cylinder from a 1966 P350 can anyone tell me the line fitting thread size going into this slave cylinder?
I doubt you'll find anyone that knows, the P series is the 'red headed stepchild' of Ford trucks, very few members have one or know much about them.

C5TZ-7A508-B .. Clutch Slave Cylinder / Obsolete ~ 22 available NOS - 1965/77 P350/500 I-6 & V8 (gas engines).

Pic: See 7A508 (1964 is different):

 
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Old May 31, 2019 | 03:46 PM
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Interesting... I wonder what cylinder I have then?
 
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Old May 31, 2019 | 03:48 PM
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It's probably some standard brake fitting.

I had an earlier version, (different, like nd says) installed for a while and if I'm not mistaken, it was setup for a 1/4" line. Could be the same size.
 
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Old Jun 1, 2019 | 02:08 PM
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Buy the line that fits the slave and put adapter at the master. Buy copper-nickel line and wrap 1 turn in it so it has some give when the engine shifts a little.
 
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Old Jun 3, 2019 | 09:47 AM
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So, buy the line that fits the slave, and adapt to the master... would I be correct in saying then that a thinner line would cause the slave to not extend fully?
 
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Old Jun 3, 2019 | 10:00 AM
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No. The line diameter has no affect on the travel of the slave cylinder. The same amount of fluid will be displaced by the master cylinder. no matter the line size and therefore, the slave will not change either.

If the line is too small by an extreme amount, you might notice additional resistance pushing the pedal and slowness to engage when the pedal is released. I think I used used 3/16" line with mine and it was fine.
 
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Old Jun 3, 2019 | 11:22 AM
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Yeah, I ended up getting line run from master to slave, and it seems the slave is not traveling far enough now... it's been a bit of a headache getting this setup together. The master cylinder I'm using is actually a new brake master cylinder from a 66 F100. I figured this would be sufficient since it normally operates four wheel cylinders but now does only one slave.

Perhaps I should put a thicker line, as I am seeing some heavy resistance at the pedal?
 
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Old Jun 3, 2019 | 11:48 AM
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One possibility is that your pedal travel is insufficient.
Another is that the cylinder bore diameters are not matched. My setup used a 1" master (actually a clutch mc) and a 1" slave. That means that the slave will travel an amount equal to the master. If the master is larger, it will be harder to push the pedal and the slave will travel farther. If the master is smaller, it will be easier to push the pedal and the slave will not travel as far.
I don't know if there is any issue with using a brake mc in the place of a clutch mc.
 
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Old Jun 3, 2019 | 11:56 AM
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It is very hard to push the pedal. So perhaps the MC is bigger. Is there a way other than switching the MC or SC to relieve that pressure and allow the pedal to go in more easily?
 
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Old Jun 3, 2019 | 12:08 PM
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You can try a bigger line.

However, as I said, the line has no affect on slave travel. If it is not traveling far enough now, figure that out and come up with a plan before spending more money.
 
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Old Jun 3, 2019 | 12:44 PM
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I think the lack of travel is due to hard clutch pedal pressure. It literally bent the plunger shaft mount I welded up.
 
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Old Jun 3, 2019 | 03:30 PM
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My thought about that is something is binding or the mount simply was not strong enough. When you said "it's a bit stuck in place now... don't ask." Maybe now is the time to ask and make sure that nothing bad is happening as a result of it being stuck.

What year is the truck it's going in?
 
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Old Jun 3, 2019 | 04:28 PM
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The truck is a 66. Maybe I need to change up the mount to make sure it's strong enough.
 
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Old Jun 4, 2019 | 03:42 PM
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I looked up my post on another website from a while back about the install of the hydraulic clutch on my '61

I need to make some corrections. Should have looked it up instead of going by memory.

I did use 1/4" line, a -4 AN brake hose with adapter fittings, to be specific. So maybe 3/16 is making the pedal harder to push.
The master cylinder was 1 1/8" bore.

Here's the thread. I don't know how much of it can be applied directly to the '66 but there is a lot of good info and pics.
http://www.slick60s.com/viewtopic.php?f=32&t=30263
 
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