Hydraulic Clutch Problem

[Meyer65]

So on my drive home from Hot August I noticed the friction point on my clutch was WAY low, like almost to the floor. I managed to make it home in one piece, and when I popped the hood I noticed the fluid in the remote reservoir was low (I am running a JMC system with an external slave cylinder)

So I added fluid which did nothing (which I figured, but it was worth a try!)

So then I decide the system needs to be re-bled (a nightmare, as many of you know)

So anyway after a lot of failed attempts I remove the slave cylinder so I can properly bleed the system.

Only here's the thing, I have essentially drained all of the fluid between the master and the slave, but the fluid level in the reservoir has not gone down even a little.

So does this indicate that the Master Cylinder is in need of a rebuild, or what? I'm not sure what to do from here...

 

[95GT]

If I am correct the fluid in the master will not go down until you press on the clutch pedal. I would get everything installed and try to bleed it out. My bet is you will be just fine.

 

[Meyer65]

Perhaps I wasn't clear about this: I originally tried to bleed the system (which inherently involves pushing down the clutch pedal) and the fluid level did not go down in the reservoir, although all of the fluid drained between the master and the slave...

 

[daveSanborn]

Depressing the clutch master should "pull" fluid out of the reservoir and shoot it down to the slave. If it's not, there's a problem with your master somewhere.

 

[95GT]

Sometimes hydraulics can act funny. I had that happen a few years ago while trying to bleed the brakes on a motorcycle. A friend told me to try something. What I did was made sure that the master cylinder was a bit low on fluid. I then took a sqeeze bottle filled with brake fluid with a hose put on the end of it and put that over the bleeder. Open the bleeder screw and force the fluid into the system. Watch to see the bubbles come up to the master cylinder and then the fluid in it should start to raise. When it does this the system should be bled out. Close the bleeder screw and try your clutch. If it works fine your good to go. If not your master cylinder might be bad.

 

[Meyer65]

In the directions for installing/bleeding the system, it says to move the slave piston out the the end of the cylinder. Right now the piston is all the way it, and I can not for the life of me figure out how to move it out. Ideas?

 

[Meyer65]

Alright, I have everything pulled apart and the master cylinder definitely needs a rebuild. I think I'll buy the rebuild kit here: http://www.racereadyproducts.com/cnc-rebuild-kits/cnc-master-cylinder-rebuild-kits/, but can anyone walk me through the process of rebuilding a CNC master cylinder? Is this difficult (i.e. something I should outsource to a professional?)? How long should it take me? I'll probably rebuild the slave cylinder while I am at it, but that looks fairly self explanatory.

 

[Fast68back]

If the rebuild kit is $30, and you outsource it, aren't you right at the point of just buying a new one? Not trying to be a smartass Derek, just figured its cheaper (long run) and faster to just replace it. Personally, I'd probably buy the kit and give it a try, how hard can it be.

 

[daveSanborn]

piston is all the way it, and I can not for the life of me figure out how to move it out. Ideas?

If the slave piston is all of the way in.... it's trapping air and needs to be bled in order to work properly.

Disconnect and remove the rod from between the slave cylinder piston and the clutch fork.

Have a helper slowly depress the clutch pedal until the slave cylinder piston is at the very end (flush) of the cylinder.

Hold your thumb over the piston, crack the bleeder on the slave and have the helper continue to slowly depress the clutch pedal.

Close the slave cylinders bleeder.


Repeating this procedure should remove any trapped air from behind the slaves piston.

 

[Meyer65]

If the rebuild kit is $30, and you outsource it, aren't you right at the point of just buying a new one? Not trying to be a smartass Derek, just figured its cheaper (long run) and faster to just replace it. Personally, I'd probably buy the kit and give it a try, how hard can it be.

Unfortunately, it is a JMC kit, so
a) JMC is no longer in business
b) the Kit cost over $500 new

While the kit does use a CNC cylinder, it was specially modified as part of the kit (the mount was moved 90* as I recall). So while I could replace it with a new CNC master (which I would love to do, believe me) I should rebuild the one I have because it fits the car perfectly.

Also, I moved the piston in the slave out when I blew compressed air into it. Technically, I shot the piston It was straight out of No Country for Old Men.

I blew compressed air through the master cylinder, but it still will not allow and fluid through it to the slave, leading me to think it is time for a rebuild.