Hydraulic clutch problem

Just put together a "70 CJ5 with small block Chevy and 11" diaphragm clutch. Has TJ hanging pedals, 80s Jeep master cyl and Novak 3/4" slave cylinder kit. The clutch pushes very hard, like over 100 pounds at the pedal. Set up the ratios close to what Novak wanted (I think). Is something wrong or did I get a super heavy duty pressure plate from Rock Auto? Anyone have a simlar setup? How hard does the pedal push?

 

Is your master the 7/8 bore?

 

Don't think it's 7/8", if I recall it's like .812"

 

OK so that's 13/16" which should be fine matched up to a 3/4" slave...............What ratio is your clutch pedal at? A standard clutch pedal needs about a 6:1 ratio , see drawing:
What does your mount from your slave to your clutch fork look like? You could also have an issue inside the clutch can. Fork wrong length, Fork not properly engaged into ball inside , fork binding on throw out bearing , could even be the wrong bearing that does not match the pressure plate correctly............lots of things to look at.

 

Tarry99 could you explain the mathematics behind your drawling? do you measure x and Y and devide the two and that's the ratio?? been on a hydro conversion for a while and am having problems.

 

Correctly Calculating Brake Pedal Ratio | Master Power Brakes

 

Thank you.

 

As Chris provided info above for Brakes..........the calculation works for both in respect to pedal ratio , just Divide X into Y..........That ratio could be all or just a part of your excessive pedal force issues . Just a place to start .............you still may have issues at the slave as that ratio from the clutch fork to the throw out bearing changes there to 2:1.

 

The pivot to pedal is 13.5" and pivot to push rod is 3.5" so 3.8 ratio, this may be my problem. The slave-push rod-fork setup is all part of the Novak kit.
Going to check the fork to see what the minimum travel is to release the clutch and adjust my pedal ratio to get it.

 

A 3.8 ratio will not be enough.................Keep this in mind: As you move the Clutch Master push rod closer to the fulcrum point above in order to gain mechanical force the travel of the push rod is now less within the bore of the cylinder. Although you will gain mechanical ability , you will also loose in piston travel within the master bore which relates to the amount of fluid you will move downstream to move your slave cylinder. Having a larger 13/16" Master is what you want in front of the 3/4" slave. There could even be the need to use a larger sized master ( More fluid ) coupled with the right pedal ratio.

That is why I mentioned earlier that at the clutch fork the ratio there is normally about 2:1..........

An average clutch pressure plate needs about .400-.600 " of travel at the throw out bearing including free play to release it from the clutch plate. That means at the clutch fork where your slave resides it must travel at least twice that above measurement or about ( .800-1.200" @ 2:1 ratio) in order to work properly...............That is why the amount of fluid transfer or movement coming from the Master Cylinder is so important.................It can be sort of a balancing act between all Items in play.

 

awesome info here in this thread!!

 

Mine is the same, except 80's Jeep Slave/10" clutch. It's some what hard to push. May not be 100lbs.