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CNC Clutch setup leaking at master already? Less than 1K miles.

3K views 30 replies 7 participants last post by  slow-poke 
Problem found (but not solved). Peeked through the clutch fork hole, and saw A302 on the pressure plate.. I suppose I didn't know what "really stiff pedal" meant when I put it in. Googling it, apparently it has QUITE the stiff pedal.. So I should probably rectify this before the spring!
I believe the A302 clutch is the King Cobra clutch from ford racing. My brother, brother-in-law and I have the same clutch in our cars, but we don't feel it's stiff by any means, although that is relative. All 3 of us have CNC masters and slaves in our cars. Just curious how the clutch master is mounted. Would you have a picture? What are you using to actuate the clutch, slave cylinder or hydraulic throwout bearing? If you mount the pushrod lower than the factory clutch rod on the pedal, that usually results in higher pedal pressure.
 
I think the C302 is the King Cobra (Not sure about kit part numbers, I mean just the PN of the pressure plate).

HEAVY DUTY 10.5" CLUTCH KIT | Part Details for M-7560-E302 | Ford Racing Performance Parts

Everything I have read has people stating the HD is QUITE stiff (While the KC is not).
You maybe right. From what I read on Ford Racing's website it indicates that pedal effort is approximately 10% more for the HD. Not sure what that equates to pedal effort wise since it's a feel thing, but I can't see 10% blowing out seals. I'm still really curious as to the setup. Do you mind posting pictures how you mounted the master cylinder?
 
Either way, mine gives you a rubbery leg after a few miles in stop and go!
I know the feeling. I use to have a clutch that was an on/off switch. Wilwood master w/ McLeod hydraulic bearing. Definitely not fun.

I can post pics a bit later, not sure when I'll be able to get in there.

I CAN tell you the height of my MC is such that you can just slide a piece of paper between the Bendix booster, and the MC, with the MC being slightly LH of the pedal.
Back to the question at hand. So I made one bad assumption and hope I'm not making another. I reread which master cylinder you used. I had assumed you used the master CNC supplied to JMC. The next assumption I'm making is that this is installed in a 65-6. Is that correct? If so, did you use the part below with the master you bought from CNC to angle it up towards the original clutch rod hole in the pedal? I'm thinking if not, you had to drill a hole in the clutch pedal 1" lower than where the factory clutch rod goes and that would definitely increase pedal effort. The size master you chose seems to be correct for the application. My brother-in-law's clutch kit is 3/4 master, 7/8 slave (nice easy pedal) whereas my brother and I have 3/4 for both (little more feedback). Another thing is the masters can be temperamental if the pushrod travel is not parallel with the bore through the full stroke. I'll wait to see the picture(s) so I don't give bad advice.
 

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3/4 for both? You aren't getting any advantage then? You just kind of made a clutch-cable out of fluid! :D
That's a good analogy. All the advantage is in the pedal ratio. My brother and I chose the same bore size to get a better feel and quicker clutch reaction. In-law's mustang almost feels like pushing air.

So yes, I'm using 3/4, 7/8... 1967. I made this kit myself, and I do remember making an angled shim! And I remember it being a REALLLLL pain to install underneath the booster! But I think I did use a lower clutch hole on the pedal, because either I wasn't getting enough travel, OR I didn't like the fact that if the master is angled up, it is NOT parallel through the travel, and starts to bend. I can't remember my reasoning though!
The lower mounting hole is definitely creating the higher pedal effort by decreasing the amount of leverage you have.

I'm currently using the angled steel master CNC use to make. Now that I know it's installed in a 67 and an idea of the setup, your master is mounted similar to when I use to have the wildwood master and McLeod hydraulic throw out bearing I mentioned earlier. Forgot to mention my brother and in-law have 66 mustangs while I have a 68 cougar. On my cougar, I too had drilled a hole in the pedal 1" lower on the clutch pedal when I didn't know better.

Also, if you decide later you want more room between the master and booster, the standard steel master should give you more room.

Daze cars has a master cylinder rod and an offset rod adapter to let you install the master straight on the firewall and use the original push rod hole on the pedal. I have it. Works great.
Bob
This looks like a good solution since the angled masters are no longer available.
 
Oh, their steel cylinder is physically smaller? Had I known that, I could have raised it up when installing it!
I believe the steel version is 1" in diameter and the aluminum version is 1.75" but I will need to double check. I actually have both. I used the aluminum version for brakes.
 
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