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1968 1750 GTV USA Bianco Spino
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Discussion Starter #1
I apologize from the beginning for starting yet another clutch bleeding thread. I've read and done what all the others did but I'm still at a loss and clutchless.

Long story:
1. I reused the benditalia master cylinder car had before restoring with a new slave bought from Classic Alfa. Also new clutch kit installed. For about a month this was good but later on gears would grind until car was warmed up for 10-15 minutes. Then it would drive normal.
2. We tried adjusting the master cylinder, this fixed the notchiness and grinding but clutch was slipping above 3K rpm. A lot.
3. I thought this would be a sign that the master cylinder had issues as it was the only thing not changed from before and might have some issues with the piston not returning. So I ordered a new one from Centerline.
4. This again resulted in clutch slip.
5. I had another new slave cylinder I had lying around that I had ordered a while back from a general parts producer. it's the same as the Classic alfa but with a longer body.
6. Installed everything and tried to bleed, just droplets came out and then air. No amount of foot pumping fixed this.
7. We bought a bleeding kit that attaches to a compressor to create vacuum. Nothing, just air.
8. We removed the slave line from the master cylinder and tried to bleed just the master. Droplets then air. No amount of adjusting (full to the left, full to the right and everything in between) fixed this.
9. We disconnected the lines, the fluid run straight out, blew air through with compressor, no foreighn bodies, no obstuctions so reattached, retried nothing.
10. Tried a reverse bleed, syringe on slave bleed port and push fluid from there in to shoot air bubbles towards the reservoir. That worked, fluid went all through the system, master rod got fully retracted. Closed everything (reservoir, nipple), still no clutch.
11. Tried manually bleeding with nipple and clutch pedal work for 5-10 minutes, nothing again. neither with slave fork manually pushed back.

I'm literally at a loss. It's the simplest circuit in the car and I just can't get it to work. It's like voodoo.
Any insights?
 

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Sometimes I find you have to just pump and pump, with the bleeder screw closed, til you begin to feel some hydraulic resistance. Can take more than 10 minutes. Once pedal starts to resist and build pressure, bleed normally.
Or use a top-down power bleeder or bottom-up vacuum or power bleeder. I don't know why these can be so tough but they are.
Andrew
 

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I feel your pain. What I resorted to in cases like this was to remove the CMC and bench bleed it using a spare cut short metal fluid tube into a clear cup. This way you can see the fluid moving into the cup, and then some of it getting sucked back in on the return stroke. Do this until there are no bubbles. Then, using another short tube either hammered shut or soldered shut (I have purchased just the hollow threaded "nut" from a local parts store and soldered it shut) remove the short tube and install the blocking tube or nut. Leave it a little loose and push piston in to purge any air then tighten it. If all the air is removed, AND it is a good CMC, you will only be able to press piston in a tiny amount before it becomes rock solid. Now you KNOW the CMC is good. Now, fill the chassis tube and hose and CSC with fluid using any method that you choose. Now simply foot bleed the system. I am assuming that you know that you have a good flex hose. The CSC can only fail in two ways. It can seize and won't move, or it leaks fluid to the ground (or fill boot). Good luck.
 

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Sounds similar to what I went through. Did you change the rubber hose leading to the slave? That turned out to be my problem. I could push fluid up through the hose but it was blocked the other way. The hose looked fine from the outside but was blocked internally.
 

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Reposition the slave cylinder in the housing, making sure the bleeder screw is at the top of the Slave cylinder (12 o'clock position).
 

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This is a floor pedal car correct? Not hanging pedals. If it's not the hose to the slave, sure sounds like your master cylinder isn't retracting enough to let fluid in.
Did your flywheel get machined? If so, is the distance between the surface the pressure plate mounts too and the friction surface correct?
 

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1968 1750 GTV USA Bianco Spino
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Discussion Starter #8
Sounds similar to what I went through. Did you change the rubber hose leading to the slave? That turned out to be my problem. I could push fluid up through the hose but it was blocked the other way. The hose looked fine from the outside but was blocked internally.
Hose is new.
 

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1968 1750 GTV USA Bianco Spino
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Discussion Starter #9
Reposition the slave cylinder in the housing, making sure the bleeder screw is at the top of the Slave cylinder (12 o'clock position).
Already done at stage 3 of the list
 

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1968 1750 GTV USA Bianco Spino
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Discussion Starter #10
This is a floor pedal car correct? Not hanging pedals. If it's not the hose to the slave, sure sounds like your master cylinder isn't retracting enough to let fluid in.
Did your flywheel get machined? If so, is the distance between the surface the pressure plate mounts too and the friction surface correct?
Yes 1969 1750 GTV US spec 105.51 dual servo with separate reservoir for clutch fluid.
Flywheel was not machined or even removed.
 

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Discussion Starter #12
I'm going throught the same issue right now. Did you find a simpler solution?
I gave up, took it to my buddy mechanic, driving without clutch hydraulics and rev matching is kinda fun, starting up on a street light not so much 😂.
Took apart the new master cylinder and we found out that the seals were shot. Might be I blew them up with all the various improvisations I tried.
Tried finding a rebuild kit and couldn't find one locally. Shipping times to an island in the times of Covid is measured in months now so I took the pump to a local rebuilder, don't know what he used but pump is working and we managed to bleed the system.
There's still some slipping over 3.5K rpm so I guess another bleed is in order but managed to take it on a 35 miles testing tour on the mountains and apart from the slight slipping everything else was OK.
There was no slipping when I drove it without pressure in the system so it's definitely not the clutch but a hydraulic issue.
 

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I just did clutch hydraulics on a 73 Spider. I used a small pressure can from below to put a few strokes of fluid into the system from the slave cylinder end and it bled much better. Took only a few minutes.
Andrew
 
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