super hard clutch pedal

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R3dplanet

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Hey gang,

I've been out for a long time with my '65 Barracuda in storage. It has a 360ci engine and a 4-speed OD gearbox with a hydraulic clutch. The slave is a concentric slave bearing from American Powertrain. The bell housing is the larger aluminum 10.5" size.

My trouble is that the clutch pedal is very hard to push. I'll swap out the master cylinder with a smaller bore unit, but I can't help but think the problem is just too heavy duty of a pressure plate.

So what's a nice soft pressure plate that will work nice with my setup? The car is a cruiser.

Thanks for any help.

-m.
 
So first, what pressure plate are you running? What is the master cylinder bore? Are you running the full American Powertrain conversion?

Second, I really doubt that the pressure plate is too heavy for that hydraulic set up. Properly set up between the slave and master cylinder that set up should be able to push darn near anything with very little pedal effort. That same slave cylinder is what they put in their kit to run in front of a T56 magnum with a 700 ft-lb rating, so nothing running on your 360 in front of a OD 833 should bother it.

I would suspect pretty much every else in the system before I suspected the pressure plate. A mismatch with the ratio between the master cylinder bore and slave cylinder, a pedal ratio issue with the master cylinder rod location, a throw out bearing clearance or stroke issue, maybe some kind of interference or a plugged line. There’s a lot involved with setting up a hydraulic clutch with an aftermarket set up like that, lots of places to go wrong. The pressure plate force is honestly the last thing I’d look at if the pedal is hard to push with that hydraulic kit.
 
My question for you is- was this all in before the storage - if so... what changed during storage. Honestly rust on the hydraulic bores or a leak / air bound check valve is all that could go wrong from sitting.
I don’t know that particular system personally but a hydraulic clutch release set are all pretty much built the same way.
Maybe rusted throw out bearing collar?

If new set up- different question.
 
Hey guys, thank you for the great responses. Just some more detail: I don't have the full American Powertrain setup. Just the slave. The master is a Wilwood compact master cylinder that I needed in order to clear the fender well.

Originally I had a Centerforce setup, but it's been a few years and I can't remember which. Last year I had some friends help me out when I was in medical treatment and they swapped out the Centerforce setup for another setup, which they said was closer to stock. I don't actually know.

The pedal geometry is good bet, but it can't be off more than half an inch, which I know can make a good bit of difference.

I'll order the master cylinder and bracket from American Powertrain. Maybe it will resolve the problem if it's a geometry problem.
 
You might try some actual diagnosis, instead of simply throwing parts at it hoping for a good outcome. Just a thought.
 
Oh, very wise. What's your approach?

Diagnosis is my approach. That's the only approach, otherwise you're guessing. Sure I could say "you might try....." or you might try..." but I don't like guessing, especially with other people's money. I'm certainly not going to try to diagnose a physical clutch problem over the internet, so I gave the only correct answer. You (or someone if you're unable) will have to diagnose it.........or get lucky throwing parts at it. Whether you like that answer or agree with it is your dilemma, not mine, but that's what's going to have to happen.

So with that, lets break down what you're asking here, ok?

First, all we get in the OP is "65 Barracuda 360, 4 speed OD" and "American Powertrain slave cylinder" with some kinda unknown clutch set with the "larger 10.5" bellhousing".

Yet, somehow we're all supposed to know from this very detailed description what your problem is.

Finally, after you were asked by a member trying to help we still only have a brand name with the slave cylinder and master cylinder. No bore sizes, no bore strokes, just "oh I got the master cylinder that fit", and some kind of "maybe close to stock pressure plate"......"I don't actually know".

I realize you have limited knowledge of "what's there" and that some friends were trying to help you out in a time of need, but expecting us to whoop out a crystal ball with such little information is expecting a bit much. Then trying to get smart with me for what was probably the best response, considering the amount of information given. I cannot jump through the internet and diagnose your car, or I would be doing it for the many friends on here that I love helping. So I suggested that you try proper diagnosis. No, I was not being smart........but you were.

Look back over your question and how it was asked. Decide for yourself if you think you gave enough info the first time, with so many unknowns. Unfortunately, you don't know much more. That would help. At this point, we're kinda shootin blanks if you will at your problem.

Did this combination ever work correctly? You didn't include that tidbit, which would help narrow it down somewhat. So it could be lots of things. Yes, it might be a mismatch between the master cylinder and slave cylinder. It could be linkage binding and or rusted up. Since you didn't give a physical description, we don't know. It could be the slave cylinder or throwout bearing binding up. It could also be a hydraulic hose that's broken down from the inside. That's how they go bad. Does it have any hard line anywhere? Someone may have accidentally crimped it somewhere. Again, this physical description was left out.

My point is, that we shouldn't have to pull answers out of you like teeth, even if the answer is "I don't know".

Like I said, I was being serious with my diagnosis answer, because truthfully that's the only answer and what you're going to have to do if you want to zero in on the problem, instead of possibly needlessly replacing parts.
 
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