Topic: clutch master cylinder assembly install gone wild

[chrisfranklin]

I recently got the clutch master cylinder assembly I ordered

Pretty straight forward I thought: Slide the pin off the clutch pedal, unscrew the old master cylinder from the fire wall, unscrew the other end of the existing assembly from the transmission and wind the whole assembly out of the engine bay.

Then get the other assembly, which is already prefilled, and simply do the "removal" in reverse, so to speak. Great, so brand new assembly and everything's good after I installed it, right? Nah!

Well I check the new resevoir to make sure the fluid is topped off. Then I start pumping the clutch pedal. It goes right to the floor. I pump the thing 100 times, nothing. I check the master cylinder resevoir in the engine bay, check for leaks...nothing.

So I Get under the jeep, check where the assembly mounts to the transmission (I'll just call this the "lower assembly" from here on). Then I decide to just unscrew the lower assembly from its port on the tranny to make sure the components on that end are ok.

Here's where I find the problem: I get the thing off and the piston had basically popped off and fluid was leaking all over the place. I slide the "lower assembly" out and see that everythng on that end had basically come apart, the spring was out, the rubber cap was off, etc.

I put everything back together in the "lower assembly" and, this time, make sure the piston seems to be contacting what I thought was the target spot in the metal port: this little concave metal surface you feel if you stick your finger inside. So I make sure that there seems to be a connection, I force the spring to compress, hold it down and then bolt the lower assembly back on. I am figuring I've got it right this second time around.

So, I get back up, check the master cylinder assembly resevoir, top it off. Then get back in the driver's seat and start pumping the clutch. Again, nothing. Same as before and the 5spd just moves through the gears without me even engaging the clutch pedal.

You guys have any tips, any thing that I should be doing? This isn't working like I expected it would. Must be doing or did something wrong.

[Mozman68]

I wish I could help, but I'm much too stupid.....

[aw12345]

Hi Chris if it has a external slave cylinder ( the one by the transmission) go to a part store and by a pump that fits on your brakefluid bottle. hook this up to the bleeder screw on the slave cylinder open the bleeder and pump brakefluid in to the system this will push the air out of the system. Just watch that the mastercylinder ( the one attached to the pedal) does not overflow. Provided you put the slave cylinder together correctly and its linkage is where it belongs you will have a the air bled out in a couple of minutes

[jfrabat]

When I changed my system (master and slave in my case) it took some pumping to get it to engage just right...  Not 200 pumps, but at least 50.  Hope you get yours to work correctly!

[Bounty Hunter]

I don't know why the clutch slave didn't engage the clutch fork the first time, it should have.  Unless you have the wrong external slave.

You may have ruined your external clutch slave when it came apart.

What year of jeep are you working on?

[chrisfranklin]

Howdy Art 

The 94 and 95 YJs seemed to come with an clutch master/slave/line assembly that is prefilled at the factory.  Basically you just install it and there is no need to bleed it. 

I found out elsewhere that you have to leave the "white plastic strip" in place on the slave assembly piston during the install.  Then once new master/slave is bolted up and line safely routed, you re-pin the master piston back to the clutch pedal and pump the clutch until the hydraulic pressure causes the white plastic strip in the slave assembly to break.  I guess the strip is there to help build pressure in the hydraulic line. 

Anyway, once the strip breaks from the pressure, the slave piston eases until it is against the "fork."  Your clutch actuation should then be back to normal.

Do it right or again.  Looks like I have to do this one again.  Costly mistake that'll remind me do my "homework" before an install next time   

[jfrabat]

Howdy Art 

The 94 and 95 YJs seemed to come with an clutch master/slave/line assembly that is prefilled at the factory.  Basically you just install it and there is no need to bleed it. 

I found out elsewhere that you have to leave the "white plastic strip" in place on the slave assembly piston during the install.  Then once new master/slave is bolted up and line safely routed, you re-pin the master piston back to the clutch pedal and pump the clutch until the hydraulic pressure causes the white plastic strip in the slave assembly to break.  I guess the strip is there to help build pressure in the hydraulic line. 

Anyway, once the strip breaks from the pressure, the slave piston eases until it is against the "fork."  Your clutch actuation should then be back to normal.

Do it right or again.  Looks like I have to do this one again.  Costly mistake that'll remind me do my "homework" before an install next time   

Oh, yeah, I forgot to mention that part about the pastic strip...  I think it was the reason I had to pump the clutch, to break the strip.