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  #1 (permalink)  
Old 07-15-2021, 04:07 AM
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Default New Master (clutch) cylinder?

(2nd attempt at posting...)

I think I need to replace my master cylinder for my clutch, but I'm not 100% sure...

I finally got my new Blue Print 347 motor installed this past fall/spring. The clutch is a new Ford Performance flywheel, clutch, and pressure plate, which seem to be a bit different than what was there in the old 302 motor. I had to do some spacing to move the pivot axis of the release fork to get enough travel so the release fork didn't bottom at the back of the scattershield. So after a few trial and errors of removing the tranny (T5) and putting some spacers on the pivot arm I finally had enough travel (1 1/4").

However, the clutch didn't release. So I got some painters tape marked off in 1/4" increments made a wire pointer and had the CEO (wife) step on the clutch while I watched total travel. It was only 1/2" at the pull point (I have a Wilwood pull type slave). With the fork release ratio that works out be 1/4" of push on the throwout bearing, clearly not enough.

So I figured maybe air in the hydraulics... and did (or tried to) bleed the line. I had my wife step on the clutch slowly, while I cracked up the bleed on the slave. Nothing. I closed the bleed and allowed her to slowly release the pedal to the top of the stroke and repeated this several times. Nothing. No fluid displaced. I checked the master and no fluid was being moved despite the pedal being pushed to the floor while the bleed was open. I closed the bleed each time before the clutch pedal was raised.

The only thing I can figure is that the master has gone bad, that fluid is leaking around the piston as it's being pushed and when released to the stop of the stroke, is swishing back around from the back of the piston to the front. It's the only thing I can figure out. Any ideas?

I guess given the car is nearly 20 years old, maybe replace BOTH the master and slave cylinder?

thanks so much for all the help you've provided over the YEARS! The good news is the Blue Print motor looks and sounds epic!

Dave K.
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  #2 (permalink)  
Old 07-16-2021, 11:15 AM
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What size is your clutch master cylinder? You'll probably need a 7/8" or 1" bore size to be compatible with the 7/8" slave.
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  #3 (permalink)  
Old 07-16-2021, 01:49 PM
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If you decide to replace them there are already at least two topics on the subject of sourcing old style master/slave cylinders here in the forum. Look at the recent list in the Shelby American subforum. Sources of AFCO and CNC have dried up.
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  #4 (permalink)  
Old 08-03-2021, 04:34 AM
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Folks, I swapped the master clutch cylinder with no change and so procured and swapped out the Wilwood slave (pull type) slave and that did the trick. Well at at least I have a basically operating clutch. It catches right off the floor and due to the configuration, there doesn't seem like I can do much with what I have.... So the clutch is operational more or less. I may yet have to move to a hydraulic throw out bearing, but that's another saga.

Thanks again!
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Old 08-03-2021, 11:36 AM
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Hydraulic throw outs are very problematic. There are many topics on the subject here. Unless perfectly aligned they eat the gaskets in the HTOB, and repairing/fixing and eliminating problems is very expensive. If you're having slave troubles go to the external slave kit from Mike Forte. It took two HTOB rebuilds before I switched and never had any more problems.
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  #6 (permalink)  
Old 08-08-2021, 02:28 PM
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Thanks kindly for the advice on the kit from Mike Forte. My clutch is more or less, somewhat working but geez it's not a great clutch and most parts are new (new Ford performance flywheel, clutch, and pressure plate, new master and new slave cylinder).
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