Why are X hydraulics so hateful?

carl

True Classic
It was a simple job, replace the leaking clutch slave cylinder with a new one. The old one worked great, the actuating nut was only half way on the actuating rod to the clutch arm. I lost very little fluid installing the new slave and two weeks later I'm still trying to get the clutch to work properly without having to push the pedal all the way into the carpet and that's with the adjusting nut all the way to the end of the rod. Yes, bled it four of five times and will have a buddy help me with a fifth. Driving the car seems to have the pedal getting better slowly. Why does it have to be such a bitch, every X owner I talk to has the same complaint.

This is a vent, not a request for helpful ideas.
 
I've done this job twice on two different X's. Both times, the only way I could get the clutch to function was with the actuating nut maxed out at the end of the rod. Both times I bled probably 2 gallons of brake fluid through the system using both a vacuum bleeder and the traditional method. I'm 99% sure there's no air in the system.

Also, prior to me messing with anything, both cars already had the nut maxed out on the end of the rod as well.

I bought a new slave cylinder assembly from MWB and noticed that the new rod I got with the slave cylinder was a few mm shorter than the old rods. Bearing that in mind, I ended up just using the old rods with the new cylinder.

As long as is works (which it does) with the nut maxed out, I've decided to not worry about it. . .

I didn't know the condition of either clutch, but both operate(d) fine.
 
only way I have had great success, is to pressure bleed crap loads of fluid thru it, at a high rate of speed. this requires a healthy crack free reservoir, with a cap for my bleeder that fits perfect. Even then it is a PIA
 
and will have a buddy help me with a fifth.
? I have always found when bleeding brakes or clutches it's a two person job. The following has always worked for me, involves a lot of shouting. Get your buddy in the drivers seat with instructions to pump clutch/brake until you yell "HOLD!!!!!!" and they then hold the pedal in.
Then undo the bleed nipple to the point of the fluid just running, not all the way out, so you can seal it quickly, then yell out "PUMP" and when you're happy it's not spluttering away, yell "HOLD!!" at which point you can judge when they've pushed the pedal in, then close the bleed nipple quickly. Yell back to your buddy "PUMP" so they test the resistance against the pedal. If it's still a bit soft, repeat. Chances are you should only need to do it 2 to 4 times.
Sorry if I'm stating the obvious, but this has always worked for me, brakes or clutch.
 
Regarding the clutch slave, I think our more clever members have concluded that it has something to do with OEM vs aftermarket slave cylinders and the specific positioning of the piston in the bore. Our Swami of Search, JimD, might be able to find those posts.
 
Wow, this thread is timely. I just spent the last couple of days completely rebuilding my pedal box. Brake master was the problem child but decided to replace the Clutch master as well. Brakes firmed up instantly but the clutch had a bubble trapped in the master. I jacked up the back and sucked from the slave with my Mityvac until a big ole' bubble of air popped out.
 
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This is point at which you will get a half-dozen suggestions about how to properly bleed the clutch slave cylinder. SOme of them quite detailed. Others lacking in specifics. No matter. None of them will work for you. That is right. You must find your own way little grasshopper. BTW, I found that reverse bleeding was the only solution for me. A pump type oil can filled with brake fluid injected at the slave cylinder. Satisfying bubbling at the fluid reservoir. This after three years of the clutch pedal being on the floor. Apparently some bubbles get trapped in the master; others get trapped in the slave.
 
More is not better. Flushing great volumes of brake fluid in then out of the clutch system is not going to cure stuck air bubble or pocket. Moving trapped air out of the clutch hydraulic system is much about persuasion and a lot less about volume of brake fluid. Ideally, fill the master cylinders when they are out of the X's pedal box then cap off the cylinders to retain brake fluid and air out. The problem happens when the cylinders are installed into a essentially level position where stuck air can and will remain stuck. Once the air pocket has been created, brake fluid simply moves over-across the air pockets-bubbles and if the fluid velocity is high, brake fluid moves over these air pockets-bubbles even easier. This is why fill and air removal with these cylinders is easier when they are out of the X and waste a whole lot less brake fluid.

Once all the hydraulic bits are installed, the clutch system MUST be flushed under pressure. Not more than 15psi at the brake fluid reservoir. Higher pressures risk damaging the plastic brake fluid reservoir and it will not move the air out of the system better.

Some years ago, this was what was done when both clutch and brake masters and pedal box were redone in the 74'..
https://xwebforums.com/forum/index.php?threads/74-pedal-box-project-part-2.25869/#post-215450

*Significant amount of what was done to the pedal box is NOT ORIGINAL... including cylinders that have been sleeved with Stainless steel. There has been zero problems with the hydraulic system since all this was done.


Bernice
 
Not a bad thread considering it was just a vent. Whatever system works for you personally is the system that works best....for you. Note, all I did was change the slave cylinder, not even the slave hose. Almost no fluid dripped out so the clutch hydraulic system should have been good to go after the swap except for maybe, just maybe nine inches back from the slave. I also think that our current crop of new slaves are probably not as good as the originals, otherwise why are all of us having to run the clutch arm actuating nut all the way out whereas the old one on this car had only been halfway along the rod and could have been the original slave.

When X fiddlers finally have a mental breakdown, the doctors recommend plenty of rest and a year playing with 128s because they are so simple even one of us could work on one successfully.....except for maybe that clutch cable thing which actually is a known brain teaser. Good luck Court, let's see how many home made spacers you have to use to get the cable adjusted right.
 
There was a generation of X clutch slave cylinders that were aluminum with a hard coating applied inside the cylinder bore. These held up GOOD.

The aftermarket clutch slaves today appear to be made of cast iron and the piston and innards are not as good as the OEM Fiat. While the clutch slave is a simple device, there are still a lot of things that can and do go wrong.

What caused the slow death of the X many a hydraulic system was the resistance to flush-changing the brake fluid every 2-3 years and proper system maintenance. When this is not done, the moisture sucked into the brake fluid ends up on the bottom of the cylinders and sits causing slow corrosion of the cylinder bore. Over time and lack of piston-cylinder movement, the bore develops pitting, seals degrade and more causing great grief.

*Years ago when the Harris Auto Museum was still together then had a Citroen SM in their collection. As with many auto museums with a sizable collection, their cars often sit on display not driven. This caused the hydraulics in the SM to seriously degrade. Their solution was to have one of the staff drive the SM often as possible, problem solved.


Bernice
 
There was a generation of X clutch slave cylinders that were aluminum with a hard coating applied inside the cylinder bore. These held up GOOD.
Bernice

That's interesting. My '68 124 wagon has an aluminum master. Not sure if it's sleeved or not as it has never been off the car.
 
Interesting commentary. The last clutch slave cylinder I got from MWB was aluminum. That was 2015 and it is still going strong....so far.
 
with all the X's I have worked on. I have not ever had a problem bleeding breaks or clutch. Normal two people pumping up and bleeding at the nipple works. Hmm, that could be read differently then met. But that could be fun as well.
 
why are all of us having to run the clutch arm actuating nut all the way out
Just a side note...not really related to bleeding.
The placement of the adjuster rod/nut will also be affected by the amount of clutch plate wear. And I've noticed that new clutches do not come with nearly as thick of lining material on them as they used to. So even a new clutch ends up like a worn one used to be. As someone mentioned, the actual length of the rod may also be shorter on a replacement slave.
But if you did not replace the clutch, and the new rod was the same length, then these are not the reasons for the adjustment being so different.
Another factor that might come into play. The adjustment of the rod at the master cylinder. Kind of a balance of clutch pedal position, and clutch actuating arm position, by adjusting both ends of the system.

As you well know, with us you can never make a rhetorical comment as a 'vent' and not get a lot of 'helpful ideas' about it. ;)
 
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